Van's Air Force
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Cooling blast tubes
- Thread starter rv72004
- Start date
We had an engineer from B&C (makers of alternators and other stuff) give a presentation at our EAA chapter meeting this week. When he asked about the need to provide cooling air to the alternator, he basically said "don't bother". Of course he was talking specifically about B&C alternators so your mileage may vary.
mcb
mcb
Rick6a
Well Known Member
Following the same line of reasoning Mel, I invested 10 whole minutes worth of work to route a 12" or so length of blast tube to the Lasar module mounted on the firewall. It may or may not prolong the life of the electronics over the long haul but what can it possibly hurt?Mel said:
Rick Galati RV-6A "Darla"
I didn't....
I didn't put blast tubes on these items on my -8, and my reasoning was based on my experience with 23 years of Grumman ownership. The AA1's run notoriously hot engine compartments, and I never had any heat-related failures of Mags or alternators, and had no blast-tubes for these items. Imprinted with a long memory of high engine temps, I wanted to make sure I didn't rob any cooling air from my new powerplant, and was extra careful not to creat any new leaks.
I am very confident that the Mags will be OK, and I guess I'll find out on the alternator! 75 hours now, and still running great - I promise to report if/when I have a failure. (Of course, you have to remember that I have a backup alternator, so I'm protected from that first failure....)
As always, YMMV!
Paul
I didn't put blast tubes on these items on my -8, and my reasoning was based on my experience with 23 years of Grumman ownership. The AA1's run notoriously hot engine compartments, and I never had any heat-related failures of Mags or alternators, and had no blast-tubes for these items. Imprinted with a long memory of high engine temps, I wanted to make sure I didn't rob any cooling air from my new powerplant, and was extra careful not to creat any new leaks.
I am very confident that the Mags will be OK, and I guess I'll find out on the alternator! 75 hours now, and still running great - I promise to report if/when I have a failure. (Of course, you have to remember that I have a backup alternator, so I'm protected from that first failure....)
As always, YMMV!
Paul
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I installed all three
I installed all three plus a heater and oil cooler hole in my baffels but carefully sealed every other unintended opening and crack. For the racing this summer I planned to plug the heater hole with a fixed plate but that was all. Ironflight got my attention if maybe just for the AirVenture Cup and the U.S. Air Race Inc. cross country races.
Bob Axsom
I installed all three plus a heater and oil cooler hole in my baffels but carefully sealed every other unintended opening and crack. For the racing this summer I planned to plug the heater hole with a fixed plate but that was all. Ironflight got my attention if maybe just for the AirVenture Cup and the U.S. Air Race Inc. cross country races.
Bob Axsom
The heat under the hoods of most cars are of the same as in the cowling of a plane and they (in many cases) use the same alternators. Besides the only time they both are subjected to the highest heat (under hood and under cowling) is when sitting still and after shutdown.
gmcjetpilot
Well Known Member
Yes and ....
Some cars do have alternators with ducted cooling to the back, however many alternators are also big 110 amps and usually run at a very low % of their max rated power. In other words they are over sized to provide power at idle when they are below the rated amps and not to run hot (for longevity). Us RV guys tend to ask 30-35 amps out of a 40-45 amp alternator on a routine basis (at least at night).
Alternators like the ND (Nippon Denso) that Van's sells has the voltage regulator on board, which can benefit from cooling. The B&C units have the regulator moved to the firewall. However all alternators have their rectifier (diodes) in the back and those can run quite hot. So even a B&C can benifit from extra air to the back. Remember the engine's exhaust pipe is right there, with its radiant heat reflecting right on the back of the alternator. At least consider some kind of heat shield between the exhaust pipe and the back of the alternator.
The internal fans of the alternator provide the main air. However look at the back of a ND alternator. You will see a heat sink. That is the voltage regulator. It likes to run cooler than hotter, even though it is rated at 250F ambient, why push it.
This comes under the heading of, it can't hurt and does help. Alternators with supplemental cooling can produce more power longer with out over heating. Fact. However you should size your alternator so its not running at rated power continuously, a good guide line is 60-75% of rated power max continuous, 50% is better. Most of the time we are down below 50%, but at night, landing we might be much higher.
I am not sure we can say a car and RV have the same temps under the cowl. If you want to be scientific about it put a temp probe on the back of the alternator and fly around with it on a hot day, all the electrics climbing with high power. Than repeat the test with some blast air. I think you will see the difference.
George
Some cars do have alternators with ducted cooling to the back, however many alternators are also big 110 amps and usually run at a very low % of their max rated power. In other words they are over sized to provide power at idle when they are below the rated amps and not to run hot (for longevity). Us RV guys tend to ask 30-35 amps out of a 40-45 amp alternator on a routine basis (at least at night).
Alternators like the ND (Nippon Denso) that Van's sells has the voltage regulator on board, which can benefit from cooling. The B&C units have the regulator moved to the firewall. However all alternators have their rectifier (diodes) in the back and those can run quite hot. So even a B&C can benifit from extra air to the back. Remember the engine's exhaust pipe is right there, with its radiant heat reflecting right on the back of the alternator. At least consider some kind of heat shield between the exhaust pipe and the back of the alternator.
The internal fans of the alternator provide the main air. However look at the back of a ND alternator. You will see a heat sink. That is the voltage regulator. It likes to run cooler than hotter, even though it is rated at 250F ambient, why push it.
This comes under the heading of, it can't hurt and does help. Alternators with supplemental cooling can produce more power longer with out over heating. Fact. However you should size your alternator so its not running at rated power continuously, a good guide line is 60-75% of rated power max continuous, 50% is better. Most of the time we are down below 50%, but at night, landing we might be much higher.
I am not sure we can say a car and RV have the same temps under the cowl. If you want to be scientific about it put a temp probe on the back of the alternator and fly around with it on a hot day, all the electrics climbing with high power. Than repeat the test with some blast air. I think you will see the difference.
George
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gmcjetpilot
Well Known Member
No I think the answer is definitely YES!RV_7A said:
(unless you have some facts Jeff?)
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mark manda
Well Known Member
you know how many alternators Rosie has been through? five.
And YOUR facts George?!
Gotta call a foul there on the logic George - reading all the posts, I see a lot of good opinions, but no data showing actual failure histories and their causes. Hey, I'm not arguing that I'm right - just keeping a level playing field for all. Is cooler generally better? Sure! But....what are the limit values? And what are the actual values?
Paul
gmcjetpilot said:No I think the answer is definitely YES!
Gotta call a foul there on the logic George - reading all the posts, I see a lot of good opinions, but no data showing actual failure histories and their causes. Hey, I'm not arguing that I'm right - just keeping a level playing field for all. Is cooler generally better? Sure! But....what are the limit values? And what are the actual values?
Paul
gmcjetpilot
Well Known Member
Well I am not flying yet..
Totally Anecdotal and I made no claim of absolute evidence or definitive data, but do offer my awesome expert opinion.
Seriously, I think it is fair to ask one who suggests that its NOT needed, what are their facts? This will not be settled until alternator temps are measured with flight testing in a RV.
The decision to use or not blast air on the "electron maker" is what engineers would consider as a "no technical objection" issue at worse and at best you will increase the longevity of the alternator.
Here is my logic if you will. I think I make a pretty compelling case to add that foot long piece of 50 cent 1/8 ounce tube for some air.
Here's the PLAN:
My plan is to get data eventually by using the open channels on my GRT engine monitor for thermocouples. Plan B, is use industrial heat indicating tape to measure temps of various items under the cowl: alternator, battery, fuel pump........ Unfortunately I am not flying my current project yet. Despite the lack of a temp survey, we do know a few things.
I am no alternator expert, but I have set up a few alternators on RVs, taken a few regulators and rectifiers apart. Also I have had discussions with several people who are experts in automotive electrics or manufacture of aftermarket parts for ND alternators. I am convinced we could be pushing the critical operating temp limit, in my every so humble opinion.
The alternator makes it own heat just generating electrical power, right. A Gentleman who was in the auto industry and now teaches auto electrics did some test of the ND on a test stand. At 100% the alternator is near or past its thermal limit on a test bench in a 70F room? What is the temp of the engine compartment 6 inches away for the exhaust stack near the exhaust port? May be its hotter? Good guess is yes, but who knows the kind of "convective" air flow going on in that area under the cowl.
It is my OPINION (emphasis on opinion) cooling air is critical if there is outside sources of heat, especially if you are asking lots of electrical power out of your alternator. So at minimum I would shield the #1 pipe from the alternator.
Now the original question posed of "Should I or NOT use blast air", make no comment on size of alternator or normal power output expected to operate at.
Let?s assume Arizona in the summer with 75% electrical load in a full power climb. Would air blast help? (Probably) A little plastic blast tube safety wired to the ass end of the alternator cost 0.50? and weighs 1/8 oz. It?s up to you. I am no salesman trying to sell anyone on this idea. I really think its a good idea, but to each his or her own.
So my opinion, theory, hypothesis is it will do no harm, likely will help in extreme conditions, costing and weighing NEXT to nothing. What is there not to like?
ANALYTICAL CALCS?
It has been awhile since I put my engineer cap on and did some thermal dynamic calculations, but assume the #1 pipe in the first 3 inches is passing gas at 1300F. What do you think the radiant heat is about, oh say 6-8" away. I don't know? I would guess roasting marshmallows. Really flight test is the only way to go here. I don't know what the convective air currents are (flow and temp) in the alternator area. May be it is a tornado under the cowl near the alternator and an auxiliary blast tube is not needed.
A simple temp probe would tell the story. If you are near the 185F limit I would do something to help cool it. CPU's in computers have similar Temp limits, but the wisdom is to keep the temp down in the 100-130F max range. (Computer geeks out there please correct me if I am wrong.)
As I stated (again opinion) a little heat shield on the #1 stack may be a good idea. Instead of a blast tube, may be a little tiny NACA scoop (1" wide) on the lower cowl in the general area of the alternator with no tube may be just enough to promote cool air to flow in that general area in the forward lower right cowl area. May be no cooling is need(?).
Again not being able to flight test my theory I leave it with the comment I made before, if you want to be scientific measure the alternators temp under max electrical load and hot conditions (engine and ambient air temp). The total max allowed temp of the semiconductors in the alternator is 85c (operation). That is 185F. The max storage temp is 150C (~302F). What is the temp just from the engine on the back of the alternator, if the alternator where idle (belt removed) during taxi, climb, cruise and approach?
Fortunately ND has a great design with two internal fans. The old school alternators with the one fan on the front had poor reliability, which is fact. The Acura's I have all have ND alternators and they have not failed in 1/2 million miles of combined driving. My old Chevy had a few replacement alternators per set of tires. I think the superior cooling of the ND alternator is what makes it more reliable than older style alternators. Why not help it out wit some air. If not for the electronics, so it for the bearings spinning 8000rpm.
George
I would highly recommend not running near 100% of the alternators capacity continuously, shield against heat and YES put some air on the back. As I said, it?s my opinion. I would love to give you some temperatures I measured but can't. ANY rocket scientist, flight test pilots willing to under take a temp survey under there cowl. I can offer moral support. Flight test is the only way to go.
Totally Anecdotal and I made no claim of absolute evidence or definitive data, but do offer my awesome expert opinion.
Seriously, I think it is fair to ask one who suggests that its NOT needed, what are their facts? This will not be settled until alternator temps are measured with flight testing in a RV.
The decision to use or not blast air on the "electron maker" is what engineers would consider as a "no technical objection" issue at worse and at best you will increase the longevity of the alternator.
Here is my logic if you will. I think I make a pretty compelling case to add that foot long piece of 50 cent 1/8 ounce tube for some air.
Here's the PLAN:
My plan is to get data eventually by using the open channels on my GRT engine monitor for thermocouples. Plan B, is use industrial heat indicating tape to measure temps of various items under the cowl: alternator, battery, fuel pump........ Unfortunately I am not flying my current project yet. Despite the lack of a temp survey, we do know a few things.
I am no alternator expert, but I have set up a few alternators on RVs, taken a few regulators and rectifiers apart. Also I have had discussions with several people who are experts in automotive electrics or manufacture of aftermarket parts for ND alternators. I am convinced we could be pushing the critical operating temp limit, in my every so humble opinion.
The alternator makes it own heat just generating electrical power, right. A Gentleman who was in the auto industry and now teaches auto electrics did some test of the ND on a test stand. At 100% the alternator is near or past its thermal limit on a test bench in a 70F room? What is the temp of the engine compartment 6 inches away for the exhaust stack near the exhaust port? May be its hotter? Good guess is yes, but who knows the kind of "convective" air flow going on in that area under the cowl.
It is my OPINION (emphasis on opinion) cooling air is critical if there is outside sources of heat, especially if you are asking lots of electrical power out of your alternator. So at minimum I would shield the #1 pipe from the alternator.
Now the original question posed of "Should I or NOT use blast air", make no comment on size of alternator or normal power output expected to operate at.
Let?s assume Arizona in the summer with 75% electrical load in a full power climb. Would air blast help? (Probably) A little plastic blast tube safety wired to the ass end of the alternator cost 0.50? and weighs 1/8 oz. It?s up to you. I am no salesman trying to sell anyone on this idea. I really think its a good idea, but to each his or her own.
So my opinion, theory, hypothesis is it will do no harm, likely will help in extreme conditions, costing and weighing NEXT to nothing. What is there not to like?
ANALYTICAL CALCS?
It has been awhile since I put my engineer cap on and did some thermal dynamic calculations, but assume the #1 pipe in the first 3 inches is passing gas at 1300F. What do you think the radiant heat is about, oh say 6-8" away. I don't know? I would guess roasting marshmallows. Really flight test is the only way to go here. I don't know what the convective air currents are (flow and temp) in the alternator area. May be it is a tornado under the cowl near the alternator and an auxiliary blast tube is not needed.
A simple temp probe would tell the story. If you are near the 185F limit I would do something to help cool it. CPU's in computers have similar Temp limits, but the wisdom is to keep the temp down in the 100-130F max range. (Computer geeks out there please correct me if I am wrong.)
As I stated (again opinion) a little heat shield on the #1 stack may be a good idea. Instead of a blast tube, may be a little tiny NACA scoop (1" wide) on the lower cowl in the general area of the alternator with no tube may be just enough to promote cool air to flow in that general area in the forward lower right cowl area. May be no cooling is need(?).
Again not being able to flight test my theory I leave it with the comment I made before, if you want to be scientific measure the alternators temp under max electrical load and hot conditions (engine and ambient air temp). The total max allowed temp of the semiconductors in the alternator is 85c (operation). That is 185F. The max storage temp is 150C (~302F). What is the temp just from the engine on the back of the alternator, if the alternator where idle (belt removed) during taxi, climb, cruise and approach?
Fortunately ND has a great design with two internal fans. The old school alternators with the one fan on the front had poor reliability, which is fact. The Acura's I have all have ND alternators and they have not failed in 1/2 million miles of combined driving. My old Chevy had a few replacement alternators per set of tires. I think the superior cooling of the ND alternator is what makes it more reliable than older style alternators. Why not help it out wit some air. If not for the electronics, so it for the bearings spinning 8000rpm.
George
I would highly recommend not running near 100% of the alternators capacity continuously, shield against heat and YES put some air on the back. As I said, it?s my opinion. I would love to give you some temperatures I measured but can't. ANY rocket scientist, flight test pilots willing to under take a temp survey under there cowl. I can offer moral support.
Flight test is the only way to go.
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dan
Well Known Member
mark manda said:
Go with a cheap alternator, and that is kinda to be expected. You'll probably end up spending the same amount of money either way. You've presumably been hearing about Bill Marvel's alternator woes on the SoCal list lately.
From what I've seen, pilots who fly IFR with all-electric setups are less likely to skimp on alternators. Will my B&C L40 last to engine TBO? Dunno, hope so. So far so good (766 hours).
Oh...and no, I don't have any blast cooling on the alternator. B&C said it was unnecessary. Ask them if you don't believe me.
)_( Dan
RV-7 N714D
http://www.rvproject.com
gmcjetpilot
Well Known Member
Show me the data
I am glad you have had great luck with your alternator Dan, I am sure it will go the distance. All the best. G
Dan I don't have to. B&C gets it opinion from Bob Nuckolls of Aeroelectrics. I have seen his comments several times. He says it does not need it and offers absolutely no reason or data as why. Of course he is a strong proponent of externally regulated alternators, specifically the B&C units which he is associated with. He has no interest in internal regulated alternators but tolerates them. I would say the on-board voltage regulator (VR), which has an IC chip, transistor, is more sensitive to temp than just the diodes in the rectifier (which all alternators have including the B&C). The ND has big heat-sinks on the VR and think if you want to be nice to it, cool it. Again semiconductors can cook and still work well above 185F but why would you want to do that. In the absence of data I would do it or measure it. I am going for it. If my flight test show it is not needed (based on temps) I'll let you all know.dan said:
I am glad you have had great luck with your alternator Dan, I am sure it will go the distance. All the best. G
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gmcjetpilot
Well Known Member
I'll call Todd Thanks
Also with a ND alternator, with the Voltage regulator still on-board, I am talking about blast air going to the VR. The B&C does not have a VR, since that is their claim to fame, they removed the VR. So if you DON'T have a B&C alternator than may be their recommendation really does not apply to internally regulated ND alternators. You need to cool the stator, rotor, rectifier and regulator. The fans are taking care of all this, especially the stator and rotor, but if its in a hot ambient environment and blowing/sucking hot air it is not as good as cool air, right.
The electronics, the rectifier (made of many diodes), I'm guessing its not as heat sensitive as the voltage regulator, which is a circuit with many components, including a IC chip and power transistors. I do think the VR can benifit from air, but that is crazy me.
Did they mention the fan is running backwards? Thanks George
Bob is Todd's man or Todd is Bobs man? I don't know but they know each other and they think alike. I'll call Todd and see if he has some reasons, Bob is not willing or able to throw any facts on the topic. I would like to know. To be honest and not to be argumentative, the 2" rule and "hurt with the cooling if it became clogged", sounds like a stretch. Again I am 90% sure that Bob is the source of at least part of Todd's opinion. The 2" rule sounds like an arbitrary Bob-ism.dan said:
Also with a ND alternator, with the Voltage regulator still on-board, I am talking about blast air going to the VR. The B&C does not have a VR, since that is their claim to fame, they removed the VR. So if you DON'T have a B&C alternator than may be their recommendation really does not apply to internally regulated ND alternators. You need to cool the stator, rotor, rectifier and regulator. The fans are taking care of all this, especially the stator and rotor, but if its in a hot ambient environment and blowing/sucking hot air it is not as good as cool air, right.
The electronics, the rectifier (made of many diodes), I'm guessing its not as heat sensitive as the voltage regulator, which is a circuit with many components, including a IC chip and power transistors. I do think the VR can benifit from air, but that is crazy me.
Did they mention the fan is running backwards? Thanks George
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mark manda
Well Known Member
Rosie was telling me(at Cable last weekend) what NAPA stands for but I forgot...
sprucemoose
Well Known Member
National Aircraft Parts & Accesories. If you play anagrams, you can almost get PMA'd out of it. Good enough for me.mark manda said:
gmcjetpilot said:
He didn't specifically say RV, but the fellow from B&C told our EAA chaper that they had test-flown an instrumented B&C alternator (without blast tube) and determined that its temperature in flight or on the ground never got close to a problematic level. You might want to call them and get the info straight from the horse's mouth.
mcb (not affiliated with B&C but will probably have at least one of their alternators on the plane)
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gmcjetpilot
Well Known Member
Please share with the class Dan
If you mean B&C is not cheap and over priced, I agree, but Dan if you think your alternator is worth almost $500 for a $180 alternator you are mistaken. I have to laugh if you think your B&C has some superiority of is better than another ND alternator that did not get anodized gold by B&C.
First you have a ND alternator, 99%. All they do is anodize it, claim to balance it (which is a laugh) and remove the regulator. Other wise its basically a ND alternator. I am not saying its not a nice product, but claims of "blue printing" and balancing the spinning mass is hype, since from the factory it is already balanced for 10,000 RPM. They are designed as high speed alternators for a reason. The applications they are designed for are high speed applications. Heard of any auto recalls where the alternator was out of balance. As much as a Lycoming shakes I don't think this is much more than a sales gimmick. Since the late 80's and early 90's manufactures like ND (the Japanese leading the way) increased efficiency with better windings and turning the alternator at faster RPMs. 8000 RPM would destroy an old generator or alternator. We run alternators at these RPMs routinely now.
The only significant change between the ND and B&C's modification of the little industrial alternator is removing the internal regulator. They claim this is more reliable. In fact there is no evidence of this and they have been spreading the urban legends and rumors that internal voltage regulators do not have OV protection. THAT IS an out right fallacy. ND alterantors are OV protected in stock form. Since stock ND alterantors (From Niagara, Van's the Auto part store) have the regulator still on board cooling air is more important.
I can assure you there have been no rotating failures of any alternators I know of. Sealed bearings can fail and have, but you have the same bearing as any ND alternator.
B&C is great with the hype, "It was a dark and stormy night and all your lights went out......... buy our (overpriced) alternator and you will be safe. Ahaaaaaa. Really, oh my gosh I better get a B&C. What happened to the BATTERY on this dark stormy panel went dark night? B&C regulators and alternators fail on regular basis. Since they are experimental, there are no great records of exact failure rates. I don't know if B&C really knows themselves. They have an idea, but I know people who replaced their failed $250 (overpriced) B&C regulator with another brand and did not contact B&C. They just threw the regulator in the junk heap.
Dan what is a cheap alternator and do you really think cheap alternators fail more? What does Rosie have? Van's rebuilds? Please share so we can avoid them ("cheap alternators"). I would agree rebuilt alternators are not as good as new genuine ND alternators. Next best is all new ND alternators CLONES. These alternators are made of new parts but from aftermarket companies. They should be better than overhauled. As far as B&C I think they are fine but way way overpriced.
In my case I went with the Niagara Air part kit (complete price and regulator w/ all hardware and brackets). It cost 1/3 to 1/4th of what B&C charges. It features a new genuine ND industrial alternator. It is small, powerful and light and just like the B&C. They are in Canada, North of Toronto and they have sold a boat load of their kit over 8 years with returns. The company owner is a pilot and has a T-18 and has flow this alternator for almost 10 years with no problems.
Cheers George
Dan I just noticed you said cheap alternator and said you have a B&C. What is a cheap alternator. I have the same alternator as you, a brand new Niagara 45 amp ND (which is a brand new genuine ND alternator), but paid 1/3rd the price. Yes cheaper but not cheap quality. Don't confuse B&C bloated over priced, over rated products as a sign of superiority of quality.dan said:
If you mean B&C is not cheap and over priced, I agree, but Dan if you think your alternator is worth almost $500 for a $180 alternator you are mistaken. I have to laugh if you think your B&C has some superiority of is better than another ND alternator that did not get anodized gold by B&C.
First you have a ND alternator, 99%. All they do is anodize it, claim to balance it (which is a laugh) and remove the regulator. Other wise its basically a ND alternator. I am not saying its not a nice product, but claims of "blue printing" and balancing the spinning mass is hype, since from the factory it is already balanced for 10,000 RPM. They are designed as high speed alternators for a reason. The applications they are designed for are high speed applications. Heard of any auto recalls where the alternator was out of balance. As much as a Lycoming shakes I don't think this is much more than a sales gimmick. Since the late 80's and early 90's manufactures like ND (the Japanese leading the way) increased efficiency with better windings and turning the alternator at faster RPMs. 8000 RPM would destroy an old generator or alternator. We run alternators at these RPMs routinely now.
The only significant change between the ND and B&C's modification of the little industrial alternator is removing the internal regulator. They claim this is more reliable. In fact there is no evidence of this and they have been spreading the urban legends and rumors that internal voltage regulators do not have OV protection. THAT IS an out right fallacy. ND alterantors are OV protected in stock form. Since stock ND alterantors (From Niagara, Van's the Auto part store) have the regulator still on board cooling air is more important.
I can assure you there have been no rotating failures of any alternators I know of. Sealed bearings can fail and have, but you have the same bearing as any ND alternator.
B&C is great with the hype, "It was a dark and stormy night and all your lights went out......... buy our (overpriced) alternator and you will be safe. Ahaaaaaa. Really, oh my gosh I better get a B&C. What happened to the BATTERY on this dark stormy panel went dark night? B&C regulators and alternators fail on regular basis. Since they are experimental, there are no great records of exact failure rates. I don't know if B&C really knows themselves. They have an idea, but I know people who replaced their failed $250 (overpriced) B&C regulator with another brand and did not contact B&C. They just threw the regulator in the junk heap.
Dan what is a cheap alternator and do you really think cheap alternators fail more? What does Rosie have? Van's rebuilds? Please share so we can avoid them ("cheap alternators"). I would agree rebuilt alternators are not as good as new genuine ND alternators. Next best is all new ND alternators CLONES. These alternators are made of new parts but from aftermarket companies. They should be better than overhauled. As far as B&C I think they are fine but way way overpriced.
In my case I went with the Niagara Air part kit (complete price and regulator w/ all hardware and brackets). It cost 1/3 to 1/4th of what B&C charges. It features a new genuine ND industrial alternator. It is small, powerful and light and just like the B&C. They are in Canada, North of Toronto and they have sold a boat load of their kit over 8 years with returns. The company owner is a pilot and has a T-18 and has flow this alternator for almost 10 years with no problems.
Cheers George
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dan
Well Known Member
I overpaid and I'm happy
I like B&C as a company. I respect the folks who work there. I have heard nothing but good recommendations from other folks who used their products. I have been happy with their products and services.
Perhaps I overpaid. I'm the sucker with the alternator that hasn't failed.
Who am I going to trust, the salesman at B&C who convinced me their alternators are superior, or some guy named "George" who won't sign his real name to anything he writes?
George, you have some agenda about Bob Nuckolls and B&C. I don't want to have anything to do with it. Can't I just be a satisfied customer? I'm being objective (if not scientific) about my experience, that's all.
)_( Dan
I like B&C as a company. I respect the folks who work there. I have heard nothing but good recommendations from other folks who used their products. I have been happy with their products and services.
Perhaps I overpaid. I'm the sucker with the alternator that hasn't failed.
Who am I going to trust, the salesman at B&C who convinced me their alternators are superior, or some guy named "George" who won't sign his real name to anything he writes?
George, you have some agenda about Bob Nuckolls and B&C. I don't want to have anything to do with it. Can't I just be a satisfied customer? I'm being objective (if not scientific) about my experience, that's all.
)_( Dan
gmcjetpilot said:
If there are I'm sure it's less than 1% of all cars built since I've been alive. It would be good info if you could tell me 1. Im sure I'd have a good comment as to why it needed additional external cooling.
gmcjetpilot said:
You are correct in saying this. However automobiles that use this size alternator are modern electronic fuel injected engines running electric fuel pumps, A/C clutches, fans, headlights and tail lights, brake lights, wind sheild wipers, radios etc all at the same time. Due to the physical size of them alone they would have no place in any RV.
gmcjetpilot said:
Which RV guys would that be? I think most folks would be hard pressed to pull 20 amps in a well layed out IFR ship even using halogen landing lights. Pulling 30-35 amps might happen breifly after intial startup until the battery comes back to stand by level. It may create some additional heat but not long enough to compound this "high heat" issue within the cowling.
gmcjetpilot said:
Now this may be a valid issue. But lets take a different approach to "radiant heat". How about a small sheild clamped directly to affected area of the alternator.
gmcjetpilot said:
This had to be the design from an engineer that probably had more data than we will ever have and obviously focused on the area most affected... the field windings.
gmcjetpilot said:
This is the only paragraph that probably says it best. Almost.
gmcjetpilot said:
This is a very honest comment. But I'd place by bet on the fact that it isn't far enough off to make this cooling thing and issue. Asides from the radiant heat thing, I'd say since these engines are air cooled and that takes place inside the baffling and oil temps are controlled by the oil cooler. Crankcase temps of an automobile and XX-360's are a pretty much the same and around 210f.
Now lets keep in mind that most of us flying above 5000 ft. and above are in somewhat cooler air than what we took off from on the ground. So until someone puts a temp sensor next to the alternator and records the actual temps of both an RV and an automobile, specifics are just not there. If you get any specifics George. Shoot them our way. Try to keep it short and simple.
But back to the poor gentlemans question.
Is it really needed. I would say NO.
-Jeff
osxuser
Well Known Member
Slow down there killer...
For whatever it's worth, 99% of 1970+ certfied aircraft DON'T have blast tubes. I think they are most a carry over from the age where electrical components were less efficient (and therefore put out more heat). The newest design I can think of that has them is the Piper Aztec.
Also for whatever it's worth, most people that build RV's don't want to 'experiment' with auto alternators, that is where companies like B&C come in. I am planning on putting one (actually two) in my -7 when I get that far. That is even though I know I can go buy a $150 1985 Suzuki Samari from NAPA that is 60Amp self regulated and bolt it up. That's because it's has been sold for the express purpose of being installed in an aircraft. Which means to some extent, I will get support on it.
For whatever it's worth, 99% of 1970+ certfied aircraft DON'T have blast tubes. I think they are most a carry over from the age where electrical components were less efficient (and therefore put out more heat). The newest design I can think of that has them is the Piper Aztec.
Also for whatever it's worth, most people that build RV's don't want to 'experiment' with auto alternators, that is where companies like B&C come in. I am planning on putting one (actually two) in my -7 when I get that far. That is even though I know I can go buy a $150 1985 Suzuki Samari from NAPA that is 60Amp self regulated and bolt it up. That's because it's has been sold for the express purpose of being installed in an aircraft. Which means to some extent, I will get support on it.
gmcjetpilot
Well Known Member
Wow one at a time?
Originally Posted by gmcjetpilot
Some cars do have alternators with ducted cooling to the back
QUOTE=RV_7A: If there are I'm sure it's less than 1% of all cars built since I've been alive. It would be good info if you could tell me 1. I'm sure I'd have a good comment as to why it needed additional external cooling.
Quattro Cabeiolet, 90, 100, A4,A6 (Audi)
325si, 540i, 735i (BMW)
900, 9000 (Saab)
You want me to keep going? (Cummings)
I will give you a hint why some have ducted air to the ass end, turbo charger and radiant heat.
I think you think I make it up as I go?
Originally Posted by gmcjetpilot
many alternators are also big 110 amps
QUOTE=RV_7A: You are correct in saying this. However automobiles that use this size alternator are modern electronic fuel injected engines running electric fuel pumps, A/C clutches, fans, headlights and tail lights, brake lights, windshield wipers, radios etc all at the same time. Due to the physical size of them alone they would have no place in any RV.
First I never made any comment that light planes and cars have the same electrical power requirements. I was only saying they are large to run enough power thru them at idle, where they are may be only able to produce 70% rated power. The hardest thing you can do is run your alternator slow and ask max out put. So your 40 amp alternator may only be a 27 amp alterntor. Field current is maxed out and the fans are making less air, which means HOT. In a plane taxing there is less air moving in the cowl. So SUPER SIZING your alternator makes sense as does COOLING BLAST AIR.
Second, "Due to the physical size of them alone they would have no place in any RV." Yea that's not true and you don't know what you are talking about. A guy named Wheeler North installed a 90 amp ND and I am helping another guy right now who needs an 80 amp alternator. I don't think its your business or mine to say what people need or not.
http://www.miramarcollege.net/programs/avim/faculty/north/alternator/index.htm
Originally Posted by gmcjetpilot
RV guys tend to ask 30-35 amps
QUOTE=RV_7A: Which RV guys would that be? I think most folks would be hard pressed to pull 20 amps in a well layed out IFR ship even using halogen landing lights. Pulling 30-35 amps might happen briefly after initial startup until the battery comes back to stand by level. It may create some additional heat but not long enough to compound this "high heat" issue within the cowling.
"Hear me now and believe me later."
Dude I am not going to get into a debate about what people need. His Name is Dave N., RV6 Builder, Phoenix AZ by the way. I'll tell you my exterior lights alone are 21 amps (both 4 amp landing lights on). No lie. The rest is about 12-14 amps worse case, and I am VFR D/N. The Gentleman I mention is up to 60 amps, by his analysis. His heated Pitot is 12-14 amps alone. I am beginning to think you think I make all this up. I am offended.
Yes it is bigger (5/2.5 lbs more) than a 40/60 amp ND, but it is 1 lb lighter than the boat anchor it replaced (an original Prestolite). They do fit. Just for the record I get by with a 40-45 amp alternator, but I am not going to question what others need or assume my needs work for every one. He needs help and I am setting him up with a 80-90 amp alternator. I think for all the guys running auto engines or lots of power hungry stuff, pitot heat, heated seats, what ever, running a big alternator will improve reliability and safety. The cooler you run the better, that is my theory and there is a well know relationship between semi conductor failure rate and temp. I am not making it up, really.
Originally Posted by gmcjetpilot
the engine's exhaust pipe is right there, with its radiant heat reflecting right on the back of the alternator
QUOTE=RV_7A: Now this may be a valid issue. But lets take a different approach to "radiant heat". How about a small shield clamped directly to affected area of the alternator.
Thanks I get lucky sometimes with a valid comment, and yea sure that is a great idea, heat shield on the alternator. Actually Nippondenso beat us both to it. They have a shield on the back already. In part as a plenum for the cooling air and shield from heat. This is conjector and my opinion on my part, but no other alternator has the "pan" like ND's do. I don't work for ND btw. However one model of ND has stands off for an additional shield. Is it for heat? Don't know but looks like it. I would at least put a little shield on the #1 exhaust stack. Radiant heat is reduced with a shield. I do believe in keeping it light, simple and per plans, so when I add extra stuff its done with thought. A heat shield can be done fairly lightly with narrow stainless straps, stand offs and aluminum shield (.025 if you want).
Originally Posted by gmcjetpilot
internal fans of the alternator provide the main air
QUOTE=RV_7A: This had to be the design from an engineer that probably had more data than we will ever have and obviously focused on the area most affected... the field windings.
Windings and cooling are kind of two things. Yes it was designed by an engineer. I was one of THEM before switching to flying for a job. Look at this link (graph 1/3rd down). I have done some research in this area.
http://www.globaldensoproducts.com/em/a/index.html
You will notice that 82' Nippondenso pioneered internal (dual) fans. By forced cooling you can run at higher field amperage with out over heating. Key to efficiency is COOLING? Hint Hint Hint.
Do You know supercomputers use (cryogenic) cooling to make them run faster. The cooler the alternator the smaller it can be. The old Delcos where not cooled well. The weight of an alternator vs. power out put has gone from 10.7 kg/kw to 2.7 kg/kw in the last 40 years. One of the biggest changes was when the integrated regulator was introduced in '74. By the way the internal REGULATOR sense temperature and if overheated with lower the out put to prevent damage. An external regulator can not do than since it is at the end of wire 5 feet way.
Originally Posted by gmcjetpilot
This comes under the heading of, it can't hurt and does help. Alternators with supplemental cooling can produce more power longer with out over heating. Fact. However you should size your alternator so its not running at rated power continuously, a good guide line is 60-75% of rated power max continuous, 50% is better. Most of the time we are down below 50%, but at night, landing we might be much higher.
This is the only paragraph that probably says it best. Almost.
Thank you, I really try to help.
Originally Posted by gmcjetpilot
I am not sure we can say a car and RV have the same temps under the cowl.
QUOTE=RV_7A: This is a very honest comment. But I'd place by bet on the fact that it isn't far enough off to make this cooling thing and issue. Asides from the radiant heat thing, I'd say since these engines are air cooled and that takes place inside the baffling and oil temps are controlled by the oil cooler. Crankcase temps of an automobile and XX-360's are a pretty much the same and around 210f.
Now lets keep in mind that most of us flying above 5000 ft. and above are in somewhat cooler air than what we took off from on the ground. So until someone puts a temp sensor next to the alternator and records the actual temps of both an RV and an automobile, specifics are just not there. If you get any specifics George. Shoot them our way. Try to keep it short and simple.
But back to the poor gentleman's question. Is it really needed. I would say NO.-Jeff
AGAIN you start off good with the part about we need to measure temps. AGREED. Thanks I try to be honest by the way.
BUT than you say NO to blast air now, really with out knowing the temp? Semantics has no business in engineering. If there is a doubt that its needed and the addition of it is of minuscule negative impact (weight, cost, construction time...), put it ON. You don't need all the main spar bolts but we put them in. I am trying to use logic and KNOWNS to come to a reasonable conclusion in the vacume of actual temp data, and you say, IS IT "REALLY" NEED IT? NO Ugh! (what does that mean really? Really what?)
What is your rational? Just a little fact or anecdote would be nice. Just give me some original opinion supported with something.
You nit pick every word I wrote, but make your own point.
I am conservative and error on the side of conservatism. I would flight test the temps tomorrow, but the only flying I am doing is at work. The RV-4 is sold and the RV-7 is under construction. I could be wrong!! Just show me the temps (ANYONE? Please ). I will be awhile before I can get it done.
Parting shot: Why not add the 0.50? plastic tube? Its cheap and light. Not withstanding B&C's comments, the ND alterantors have a regulator that is mounted to the back and "could" benifit from cooling air. [/B]
Originally Posted by gmcjetpilot
Some cars do have alternators with ducted cooling to the back
QUOTE=RV_7A: If there are I'm sure it's less than 1% of all cars built since I've been alive. It would be good info if you could tell me 1. I'm sure I'd have a good comment as to why it needed additional external cooling.
Quattro Cabeiolet, 90, 100, A4,A6 (Audi)
325si, 540i, 735i (BMW)
900, 9000 (Saab)
You want me to keep going? (Cummings)
I will give you a hint why some have ducted air to the ass end, turbo charger and radiant heat.
I think you think I make it up as I go?
Originally Posted by gmcjetpilot
many alternators are also big 110 amps
QUOTE=RV_7A: You are correct in saying this. However automobiles that use this size alternator are modern electronic fuel injected engines running electric fuel pumps, A/C clutches, fans, headlights and tail lights, brake lights, windshield wipers, radios etc all at the same time. Due to the physical size of them alone they would have no place in any RV.
First I never made any comment that light planes and cars have the same electrical power requirements. I was only saying they are large to run enough power thru them at idle, where they are may be only able to produce 70% rated power. The hardest thing you can do is run your alternator slow and ask max out put. So your 40 amp alternator may only be a 27 amp alterntor. Field current is maxed out and the fans are making less air, which means HOT. In a plane taxing there is less air moving in the cowl. So SUPER SIZING your alternator makes sense as does COOLING BLAST AIR.
Second, "Due to the physical size of them alone they would have no place in any RV." Yea that's not true and you don't know what you are talking about. A guy named Wheeler North installed a 90 amp ND and I am helping another guy right now who needs an 80 amp alternator. I don't think its your business or mine to say what people need or not.
http://www.miramarcollege.net/programs/avim/faculty/north/alternator/index.htm
Originally Posted by gmcjetpilot
RV guys tend to ask 30-35 amps
QUOTE=RV_7A: Which RV guys would that be? I think most folks would be hard pressed to pull 20 amps in a well layed out IFR ship even using halogen landing lights. Pulling 30-35 amps might happen briefly after initial startup until the battery comes back to stand by level. It may create some additional heat but not long enough to compound this "high heat" issue within the cowling.
"Hear me now and believe me later."
Dude I am not going to get into a debate about what people need. His Name is Dave N., RV6 Builder, Phoenix AZ by the way. I'll tell you my exterior lights alone are 21 amps (both 4 amp landing lights on). No lie. The rest is about 12-14 amps worse case, and I am VFR D/N. The Gentleman I mention is up to 60 amps, by his analysis. His heated Pitot is 12-14 amps alone. I am beginning to think you think I make all this up. I am offended.
Yes it is bigger (5/2.5 lbs more) than a 40/60 amp ND, but it is 1 lb lighter than the boat anchor it replaced (an original Prestolite). They do fit. Just for the record I get by with a 40-45 amp alternator, but I am not going to question what others need or assume my needs work for every one. He needs help and I am setting him up with a 80-90 amp alternator. I think for all the guys running auto engines or lots of power hungry stuff, pitot heat, heated seats, what ever, running a big alternator will improve reliability and safety. The cooler you run the better, that is my theory and there is a well know relationship between semi conductor failure rate and temp. I am not making it up, really.
Originally Posted by gmcjetpilot
the engine's exhaust pipe is right there, with its radiant heat reflecting right on the back of the alternator
QUOTE=RV_7A: Now this may be a valid issue. But lets take a different approach to "radiant heat". How about a small shield clamped directly to affected area of the alternator.
Thanks I get lucky sometimes with a valid comment, and yea sure that is a great idea, heat shield on the alternator. Actually Nippondenso beat us both to it. They have a shield on the back already. In part as a plenum for the cooling air and shield from heat. This is conjector and my opinion on my part, but no other alternator has the "pan" like ND's do. I don't work for ND btw. However one model of ND has stands off for an additional shield. Is it for heat? Don't know but looks like it. I would at least put a little shield on the #1 exhaust stack. Radiant heat is reduced with a shield. I do believe in keeping it light, simple and per plans, so when I add extra stuff its done with thought. A heat shield can be done fairly lightly with narrow stainless straps, stand offs and aluminum shield (.025 if you want).
Originally Posted by gmcjetpilot
internal fans of the alternator provide the main air
QUOTE=RV_7A: This had to be the design from an engineer that probably had more data than we will ever have and obviously focused on the area most affected... the field windings.
Windings and cooling are kind of two things. Yes it was designed by an engineer. I was one of THEM before switching to flying for a job. Look at this link (graph 1/3rd down). I have done some research in this area.
http://www.globaldensoproducts.com/em/a/index.html
You will notice that 82' Nippondenso pioneered internal (dual) fans. By forced cooling you can run at higher field amperage with out over heating. Key to efficiency is COOLING? Hint Hint Hint.
Do You know supercomputers use (cryogenic) cooling to make them run faster. The cooler the alternator the smaller it can be. The old Delcos where not cooled well. The weight of an alternator vs. power out put has gone from 10.7 kg/kw to 2.7 kg/kw in the last 40 years. One of the biggest changes was when the integrated regulator was introduced in '74. By the way the internal REGULATOR sense temperature and if overheated with lower the out put to prevent damage. An external regulator can not do than since it is at the end of wire 5 feet way.
Originally Posted by gmcjetpilot
This comes under the heading of, it can't hurt and does help. Alternators with supplemental cooling can produce more power longer with out over heating. Fact. However you should size your alternator so its not running at rated power continuously, a good guide line is 60-75% of rated power max continuous, 50% is better. Most of the time we are down below 50%, but at night, landing we might be much higher.
This is the only paragraph that probably says it best. Almost.
Thank you, I really try to help.
Originally Posted by gmcjetpilot
I am not sure we can say a car and RV have the same temps under the cowl.
QUOTE=RV_7A: This is a very honest comment. But I'd place by bet on the fact that it isn't far enough off to make this cooling thing and issue. Asides from the radiant heat thing, I'd say since these engines are air cooled and that takes place inside the baffling and oil temps are controlled by the oil cooler. Crankcase temps of an automobile and XX-360's are a pretty much the same and around 210f.
Now lets keep in mind that most of us flying above 5000 ft. and above are in somewhat cooler air than what we took off from on the ground. So until someone puts a temp sensor next to the alternator and records the actual temps of both an RV and an automobile, specifics are just not there. If you get any specifics George. Shoot them our way. Try to keep it short and simple.
But back to the poor gentleman's question. Is it really needed. I would say NO.-Jeff
AGAIN you start off good with the part about we need to measure temps. AGREED. Thanks I try to be honest by the way.
BUT than you say NO to blast air now, really with out knowing the temp?
Semantics has no business in engineering. If there is a doubt that its needed and the addition of it is of minuscule negative impact (weight, cost, construction time...), put it ON. You don't need all the main spar bolts but we put them in. I am trying to use logic and KNOWNS to come to a reasonable conclusion in the vacume of actual temp data, and you say, IS IT "REALLY" NEED IT? NO Ugh! (what does that mean really? Really what?)What is your rational? Just a little fact or anecdote would be nice. Just give me some original opinion supported with something.
You nit pick every word I wrote, but make your own point.
I am conservative and error on the side of conservatism. I would flight test the temps tomorrow, but the only flying I am doing is at work. The RV-4 is sold and the RV-7 is under construction. I could be wrong!!
Just show me the temps (ANYONE? Please ). I will be awhile before I can get it done. Parting shot: Why not add the 0.50? plastic tube? Its cheap and light. Not withstanding B&C's comments, the ND alterantors have a regulator that is mounted to the back and "could" benifit from cooling air. [/B]
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gmcjetpilot
Well Known Member
Darn Dan
Sorry if I offended you with my opinion that B&C products are good but overpriced, I am sorry. However I am not the only one who says that. I never said you where a sucker BTW.
As far as my name you have it, when I emailed you this summer to tell you where to go in New Orleans (lived there, faimly is from there). If you want I will send you a copy of my passport and ATP licence. I don't put my last name on post to public. To trusted people I am glad to tell my life story. By hostility like yours re-affirms my desire to avoid having any old SOG knowing my name, home address and social security number. Sorry again if that offends you, but too bad. George is my real name.
If think that your B&C is superior, good for you, it may very well be. The truth is there are all kinds of weird things going on (or not) with that "crow-bar" inside that B&C voltage regulator. So just be careful out there in IMC IFR, you are not immune from failure with B&C products. I have a friend with a burned up one on his bench.
Last: you did not answer the question, what is a cheap alternator?
You throw out a condescending
"Go with a cheap alternator, and that is kinda to be expected."
What are you talking about.
What cheap alternator?
Why should we expect failure?
What kind of failure?
I respect you enough to ask what you meant. I did not intend to piss you off by asking you what you mean. I thought you might know something. I won't make that mistake again. Geeeee
I guess any alternator is a cheap alternator compared to a B&C and thus subject to failure. Don't tell the world, where there are millions of ND alterantors going 24/7, year in and year out, in cars, trucks, tractors, folk-lifts and YES experimental aircraft with no failure. I guess we are on borrowed time, but you kinda expect that with a cheap alternators?
Dan, you are as opinionated as I am, and I don't get mad at you when you repeat for the millionth time how superior the tip up canopy is. Yes I have a slider, proving once again I am not as smart as you.
Cheers George RV-4, RV-6, RV-7 (is that a better sign off)
As usual you are VERY satisfied with your choice. I wish I could always make the right decision like you, but I am not that smart.dan said:
Sorry if I offended you with my opinion that B&C products are good but overpriced, I am sorry. However I am not the only one who says that. I never said you where a sucker BTW.
As far as my name you have it, when I emailed you this summer to tell you where to go in New Orleans (lived there, faimly is from there). If you want I will send you a copy of my passport and ATP licence. I don't put my last name on post to public. To trusted people I am glad to tell my life story. By hostility like yours re-affirms my desire to avoid having any old SOG knowing my name, home address and social security number. Sorry again if that offends you, but too bad. George is my real name.
If think that your B&C is superior, good for you, it may very well be. The truth is there are all kinds of weird things going on (or not) with that "crow-bar" inside that B&C voltage regulator. So just be careful out there in IMC IFR, you are not immune from failure with B&C products. I have a friend with a burned up one on his bench.
Last: you did not answer the question, what is a cheap alternator?
You throw out a condescending
"Go with a cheap alternator, and that is kinda to be expected."
What are you talking about.
What cheap alternator?
Why should we expect failure?
What kind of failure?
I respect you enough to ask what you meant. I did not intend to piss you off by asking you what you mean. I thought you might know something. I won't make that mistake again. Geeeee
I guess any alternator is a cheap alternator compared to a B&C and thus subject to failure. Don't tell the world, where there are millions of ND alterantors going 24/7, year in and year out, in cars, trucks, tractors, folk-lifts and YES experimental aircraft with no failure. I guess we are on borrowed time, but you kinda expect that with a cheap alternators?
Dan, you are as opinionated as I am, and I don't get mad at you when you repeat for the millionth time how superior the tip up canopy is. Yes I have a slider, proving once again I am not as smart as you.
Cheers George RV-4, RV-6, RV-7
(is that a better sign off)
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gmcjetpilot
Well Known Member
Don't believe me?
I can't believe that anyone doubts that cooling of electronics is not a good thing.
This 2 minute video is of a couple of brain surgeons blowing up CPU's by pulling the heat sink and fan off the CPU. The CPU blows up spectacularly.
They first blow up an AMD Duron, than repeat the precess of "blowing things up" with a Pentium 4. The first processor (CPU) blows up about 50 seconds into the video.
http://www.dumpalink.com/media/1137065926/Exploding_Computer_Processors
If you doubt that blowing a little air on the heat sink of the voltage regulator is a waste, look at the video. The VR has a chip inside, albeit not a computer CPU, the field control transistor can run 4-5 amps thru it. George
I can't believe that anyone doubts that cooling of electronics is not a good thing.
This 2 minute video is of a couple of brain surgeons blowing up CPU's by pulling the heat sink and fan off the CPU. The CPU blows up spectacularly.
They first blow up an AMD Duron, than repeat the precess of "blowing things up" with a Pentium 4. The first processor (CPU) blows up about 50 seconds into the video.
http://www.dumpalink.com/media/1137065926/Exploding_Computer_Processors
If you doubt that blowing a little air on the heat sink of the voltage regulator is a waste, look at the video. The VR has a chip inside, albeit not a computer CPU, the field control transistor can run 4-5 amps thru it. George
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gmcjetpilot said:
With all due respect, George, Pentiums have about as much in common with alternators and voltage regulators as hemp rope has in common with a joint. They're made out of the same "stuff", but I fail to see the relevance of the video as it relates to alternators. They're totally different in function and characteristics.
On the other hand, if someone intends on installing an AMD Duron under their cowl, I think you have quite a strong case that additional cooling air is a good idea.
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robertahegy
Moderator/Tech Counselor
If you all would spend this much energy building, you all would be flying instead of arguing. Please go exercise that rivet gun instead of exercising futility.
Roberta
Roberta
dan
Well Known Member
gmcjetpilot said:
I take back that statement about cheap alternators, because I don't have any hard data to back it up.
All I can say is -- I read that quote about somebody having gone through 5 alternators in ~2300 hours. I know him personally and recall that he said he uses an inexpensive alternator. I don't know exactly what type, where he got it, etc. I just know it's not one of the expensive B&C ones (and yes, I agree B&C stuff is overpriced...but I still buy it for the warm fuzzies it gives me).
GMC, I'm not saying my choices are smarter or the right ones. They're the right ones for me, though. And that's what counts. These are experimental amateur built airplanes, which means you can do it your way.
Back to the topic...cooling blast tube. You can do it your way. If it gives you warm fuzzies to put in a cooling blast tube, by all means do it.
)_( Dan
RV-7 N714D
http://www.rvproject.com
gmcjetpilot
Well Known Member
Warm Fuzzies back at Ya
Cheers George.
As usual it turns out we where in 100% a agreement or have mutual appreciation of the other opinions in the end, after all, even if they may not be our own. Thanks Dan, I feel warm fuzzies all over my little body. It tickles.dan said:
Cheers George.
gmcjetpilot
Well Known Member
Yes but you missed the point
http://www.ortodoxism.ro/datasheets/motorola/MC33099.pdf
It is no Pentium 4 (with 55 million equivalent transistors) but the voltage regulator it is way more complex than I think you might imagine. Some VR's are simple and made from a few discrete components, with a handful of transistors. However ND alterantors have fault detection, hi/lo volt warning, short protection, load dump protection, over voltage protection, timers and soft start functions to name only a few. These are things that B&C voltage regulators don't do, but urban legend has it the stock I-VR does not protect against Over Voltage (OV) or is reliable and is subject to failure. Nothing can be further from the truth. It is silly stuff. Most of these things come from old electrical systems an Cessna's or Pipers, which frankly are old 50's auto technology. There where all kind of issues. Trust me a cool ND alternator with a I-VR is many many times more reliable and stable.
Also in the VR package on an internal regulator is a field driver power transistor (separate from the IC chip): This FET or Insulated Gate Bipolar Transistor (IGBT like a power NPN) is pumping up to 4-5 amps at max output and can run hot. Again cooling is good, heat bad. Really, trust me. If you don't believe me watch the Pentium 4 blows up clip one more time. The same thing can happen to a diode, resistor, transistor or any part that exceeds its thermal limit, whether in a stereo or voltage regulator. That is the point. COOLING IS GOOD
I assume you know about electronics. So I am sure you believe "cooling is good for semi conductors". Its like CHT. Sure you can fly around at 420F all day but 380F is a lot better for the valves. Both are in the limits. Same with the voltage regulator, keep it cool it will be happier.
I guess we all will agree to dis-agree. I till say that cooling will have positive affect on reliability of alternators, especially those with on board VR's. Keep cool my Babies. That is the end of that for me. Be hot be cool do as you like. I think it is worth it. If you have a B&C I would follow their recommendations.
UNDERSTANDING THE INTERNAL VOLTAGE REGULATOR VS. EXTERNAL
The only way to do get all the advanced functions in an I-VR is with advance IC chip technology verses discrete components like a B&C VR. I am guessing the ND voltage regulator (IC) has 100's if not 100's equivalent transistors, including digital control!!!! (like a computer processor). In fact future alternators will have a digital data connection to the car's computer, but we digress. The B&C regulator is fine, but is only made with a hand full of discrete parts. It is really a true voltage regulator with something called a crow bar on top to protect from over voltage. The crow bar SHORTS itself to ground to blow a circuit breaker to stop the alternator. It works but it does it by throwing the proverbial "Crow bar" across you buss to gound. Ouch!
This is not a put down of B&C. THEY MAKE GREAT STUFF. It works and is dead simple which is an advantage, not a draw back. This is why people like B&C and Bob are comfortable with it. It works and is simple and they have been doing it this way in one form or another for 30 years. If it ain't broke don't fix it. However the auto industry has moved on, and since we rely on automotive alternators for your experimental planes, there just are not any good alternators set up for external regulation since the early 80's. Those are around but they are not up to the standards of later designs, including internal dual cooling fans. (AGAIN COOLING MADE ALTERNATORS MORE reliable.) I can't emphasise how important cooling is. Really there just are not good (small) alternators made today that don't have I-VR. So you are left with using it as is, removing it yourself, clumsy and a bit of a kludge, or going with B&C (AND COOLING IT). All valid choices.
As far as B&C and their recommendation, they are proponents of external regulation (and only sell modified ND alterantors with the VR removed). They do not speak for the internally regulated ND alternators that are in 1000's of experimental home built planes (not to mention the millions of cars). In fact they have a long standing "doctrine" of not recommending internally regulated alternators. That's cool. The thing is internal regulation is the state of the art, and if an internally regulated alternator is installed, operated as intended with in the limits (including temp), they are very reliable.
Some of the "bad luck" I-VR users can trace their issues to one of three problems: They are operating the alternator improperly (turning it on and off under load), Wired it incorrectly (not using the remote volt sense or the integral warning/fault light available on most models) and last they are buying poor quality rebuilds**. Part of the problem may be a combo of lower quality rebuilds or parts, combined with over temperature. Again COOLING.
Prove I am wrong please. B&C would love everyone to toast their ND alternator and buy their product. If I was them I also would want that. Nothing wrong with capitalism. I am not saying B&C want non B&C alternators to fail, but they are NOT advocates, or are they to be used as a source of info on how to install and use internally regulated alternators. It is not their expertise. There not going to help you, since frankly it is not a sales. Nice guys yes but internal regulator champions, no.
I have tracked many of the rumors and urban legends. If you get a good quality alternator (rebuild or new), don't turn the ALT switch on an off with the engine turning, cool it (out of conservatism and knowing cool electronics are happy electronics) and wire the warning/fault light up and remote sense (if that model has it), you will eliminate 99% of the problems I have seen.
The OV protection BTW defaults to 17 volts (not infinity as legend says). Some have had problems but it is because they don't know how the regulator works and the proper procedures to handle a "NON normal" condition. The only truly reliable way to isolate a failed alternator output (with an internal VR) is have a pull-able Circuit Breaker (CB) in the instrument panel, for on the output lead (called the b-lead). This is where wiring in the fault light comes in. It illuminates you pull the CB. It does require pilot action. 17 volts should not damage battiers or avionics, which now almost all avionics run on 10-30 volts, at least if you turn the alternator off sooner than later.
To be fair their (B&C) solution was to move the VR to a remote cooler location. Hey that works and it is an advantage, but with modern electronics and manufacturing VR's can live on a hot and vibrating alternator just fine. The ND VR has a heat sink on it for a reason. Blowing air on it (convective cooling can do wonders, see computer blowing up clip again).
Also I-VR was introduced in the 70's. No doubt the first ones are not as good. However from my research Nippondenso (ND) has one of the best designs, most protection and reliability. HOW CAN I SAY THAT? I research 30 years of The Highway safety foundation the data base for alternator issues of all brands. This is a data base that tracks all the Service bulletins, recalls, consumer complaints and accidents caused but defective automotive designs. The ND brand has a fantastic trouble free history. Not true of some other brands, Bosch, Hitachi and of course a smattering of Ford, Chrysler and Chevy alternators. ND is the best followed by Mitsubishi, IN MY OPINION.
G
** State of the automotive electrical industry, rebuild alternators:
The automotive electronics rebuild industry is getting away from rebuilding old cores. Cores are getting older now and by the time you tear it down and rebuild it, its cheaper to build a new alternator made of 100% after market parts. Now the debate is are after market parts as reliable as genuine ND parts. I have researched it and the answer is yes and no; there are many aftermarket part makers; some are better than others, but it is the wave of the future. I would not buy and use a rebuilt alternator myself if new was available. In the past new was not available at all from some models (genuine or after-market), but that's changing as the after-market has stepped up and decided to make all components. It is like the clone Lycomings. They (Superior and ECI) always made cylinders, but eventually they made more and more parts until they could make a whole engine. Same with the non-OEM auto electric part makers. The demand for alternators from the 80's and 90's is still there. New alternators for cars are so large they are not as suitable for out needs. The only new alternator from Nippondenso are the smaller industrial units or the large car alternators.
Boy talk about taking it literal, it is a valid point I made, and I'll explain. There is an IC chip (like a CPU) in an internal voltage regulator, and they can have and do have DIGITAL process control. Did you know that. I didn't and was surprised to see how complicated they are. They are in fact little microprocessors. Here is a spec sheet for a automotive voltage regulator IC chip: (page 2)jcoloccia said:With all due respect, George, Pentiums have about as much in common with alternators and voltage regulators as hemp rope has in common with a joint. They're made out of the same "stuff", but I fail to see the relevance of the video as it relates to alternators. They're totally different in function and characteristics. (NOT REALLY)
On the other hand, if someone intends on installing an AMD Duron under their cowl, I think you have quite a strong case that additional cooling air is a good idea.
http://www.ortodoxism.ro/datasheets/motorola/MC33099.pdf
It is no Pentium 4 (with 55 million equivalent transistors) but the voltage regulator it is way more complex than I think you might imagine. Some VR's are simple and made from a few discrete components, with a handful of transistors. However ND alterantors have fault detection, hi/lo volt warning, short protection, load dump protection, over voltage protection, timers and soft start functions to name only a few. These are things that B&C voltage regulators don't do, but urban legend has it the stock I-VR does not protect against Over Voltage (OV) or is reliable and is subject to failure. Nothing can be further from the truth. It is silly stuff. Most of these things come from old electrical systems an Cessna's or Pipers, which frankly are old 50's auto technology. There where all kind of issues. Trust me a cool ND alternator with a I-VR is many many times more reliable and stable.
Also in the VR package on an internal regulator is a field driver power transistor (separate from the IC chip): This FET or Insulated Gate Bipolar Transistor (IGBT like a power NPN) is pumping up to 4-5 amps at max output and can run hot. Again cooling is good, heat bad. Really, trust me. If you don't believe me watch the Pentium 4 blows up clip one more time. The same thing can happen to a diode, resistor, transistor or any part that exceeds its thermal limit, whether in a stereo or voltage regulator. That is the point. COOLING IS GOOD
I assume you know about electronics. So I am sure you believe "cooling is good for semi conductors". Its like CHT. Sure you can fly around at 420F all day but 380F is a lot better for the valves. Both are in the limits. Same with the voltage regulator, keep it cool it will be happier.
I guess we all will agree to dis-agree. I till say that cooling will have positive affect on reliability of alternators, especially those with on board VR's. Keep cool my Babies. That is the end of that for me. Be hot be cool do as you like. I think it is worth it. If you have a B&C I would follow their recommendations.
UNDERSTANDING THE INTERNAL VOLTAGE REGULATOR VS. EXTERNAL
The only way to do get all the advanced functions in an I-VR is with advance IC chip technology verses discrete components like a B&C VR. I am guessing the ND voltage regulator (IC) has 100's if not 100's equivalent transistors, including digital control!!!! (like a computer processor). In fact future alternators will have a digital data connection to the car's computer, but we digress. The B&C regulator is fine, but is only made with a hand full of discrete parts. It is really a true voltage regulator with something called a crow bar on top to protect from over voltage. The crow bar SHORTS itself to ground to blow a circuit breaker to stop the alternator. It works but it does it by throwing the proverbial "Crow bar" across you buss to gound. Ouch!
This is not a put down of B&C. THEY MAKE GREAT STUFF. It works and is dead simple which is an advantage, not a draw back. This is why people like B&C and Bob are comfortable with it. It works and is simple and they have been doing it this way in one form or another for 30 years. If it ain't broke don't fix it. However the auto industry has moved on, and since we rely on automotive alternators for your experimental planes, there just are not any good alternators set up for external regulation since the early 80's. Those are around but they are not up to the standards of later designs, including internal dual cooling fans. (AGAIN COOLING MADE ALTERNATORS MORE reliable.) I can't emphasise how important cooling is. Really there just are not good (small) alternators made today that don't have I-VR. So you are left with using it as is, removing it yourself, clumsy and a bit of a kludge, or going with B&C (AND COOLING IT). All valid choices.
As far as B&C and their recommendation, they are proponents of external regulation (and only sell modified ND alterantors with the VR removed). They do not speak for the internally regulated ND alternators that are in 1000's of experimental home built planes (not to mention the millions of cars). In fact they have a long standing "doctrine" of not recommending internally regulated alternators. That's cool. The thing is internal regulation is the state of the art, and if an internally regulated alternator is installed, operated as intended with in the limits (including temp), they are very reliable.
Some of the "bad luck" I-VR users can trace their issues to one of three problems: They are operating the alternator improperly (turning it on and off under load), Wired it incorrectly (not using the remote volt sense or the integral warning/fault light available on most models) and last they are buying poor quality rebuilds**. Part of the problem may be a combo of lower quality rebuilds or parts, combined with over temperature. Again COOLING.
Prove I am wrong please. B&C would love everyone to toast their ND alternator and buy their product. If I was them I also would want that. Nothing wrong with capitalism. I am not saying B&C want non B&C alternators to fail, but they are NOT advocates, or are they to be used as a source of info on how to install and use internally regulated alternators. It is not their expertise. There not going to help you, since frankly it is not a sales. Nice guys yes but internal regulator champions, no.
I have tracked many of the rumors and urban legends. If you get a good quality alternator (rebuild or new), don't turn the ALT switch on an off with the engine turning, cool it (out of conservatism and knowing cool electronics are happy electronics) and wire the warning/fault light up and remote sense (if that model has it), you will eliminate 99% of the problems I have seen.
The OV protection BTW defaults to 17 volts (not infinity as legend says). Some have had problems but it is because they don't know how the regulator works and the proper procedures to handle a "NON normal" condition. The only truly reliable way to isolate a failed alternator output (with an internal VR) is have a pull-able Circuit Breaker (CB) in the instrument panel, for on the output lead (called the b-lead). This is where wiring in the fault light comes in. It illuminates you pull the CB. It does require pilot action. 17 volts should not damage battiers or avionics, which now almost all avionics run on 10-30 volts, at least if you turn the alternator off sooner than later.
To be fair their (B&C) solution was to move the VR to a remote cooler location. Hey that works and it is an advantage, but with modern electronics and manufacturing VR's can live on a hot and vibrating alternator just fine. The ND VR has a heat sink on it for a reason. Blowing air on it (convective cooling can do wonders, see computer blowing up clip again).
Also I-VR was introduced in the 70's. No doubt the first ones are not as good. However from my research Nippondenso (ND) has one of the best designs, most protection and reliability. HOW CAN I SAY THAT? I research 30 years of The Highway safety foundation the data base for alternator issues of all brands. This is a data base that tracks all the Service bulletins, recalls, consumer complaints and accidents caused but defective automotive designs. The ND brand has a fantastic trouble free history. Not true of some other brands, Bosch, Hitachi and of course a smattering of Ford, Chrysler and Chevy alternators. ND is the best followed by Mitsubishi, IN MY OPINION.
G
** State of the automotive electrical industry, rebuild alternators:
The automotive electronics rebuild industry is getting away from rebuilding old cores. Cores are getting older now and by the time you tear it down and rebuild it, its cheaper to build a new alternator made of 100% after market parts. Now the debate is are after market parts as reliable as genuine ND parts. I have researched it and the answer is yes and no; there are many aftermarket part makers; some are better than others, but it is the wave of the future. I would not buy and use a rebuilt alternator myself if new was available. In the past new was not available at all from some models (genuine or after-market), but that's changing as the after-market has stepped up and decided to make all components. It is like the clone Lycomings. They (Superior and ECI) always made cylinders, but eventually they made more and more parts until they could make a whole engine. Same with the non-OEM auto electric part makers. The demand for alternators from the 80's and 90's is still there. New alternators for cars are so large they are not as suitable for out needs. The only new alternator from Nippondenso are the smaller industrial units or the large car alternators.
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re: exploding computers
Here's a better link with the full clips. Watch the final clip and decided for yourself if all the smoke billowing out from under the table and the "hissing" sound is from an exploading pentium or a very large firecracker (the stupid chip miraculously doesn't even "explode" in the last clip but the heat sink goes flying off...hmmm)
http://edge.i-hacked.com/make-processors-explode
Some components have lithium batteries in them, and you can make those overheat and explode by shorting out the appropriate pins (very dangerous when this happens).
Anyhow, the question isn't does it need cooling. The question is how hot can it get until it's performance/life degrades unexceptably, and how hot is it currently getting in a specific installation (if you're worried about that sort of thing). Since we're all running (or in my case will be running) installations that are different than everyone elses, I suspect that there are some that are fine with no additional cooling, and some that are being slowly cooked to death even with additional cooling.
This is why I intend to run a couple of extra wires through my firewall and into my engine monitor or fluke meter. I'll be able to temporarily install a thermocouple (or whatever) anywhere I want to answer just this sort of question if I ever feel like it. What can I say? I'm an engineer, and I like having telemetry.
Here's a better link with the full clips. Watch the final clip and decided for yourself if all the smoke billowing out from under the table and the "hissing" sound is from an exploading pentium or a very large firecracker (the stupid chip miraculously doesn't even "explode" in the last clip but the heat sink goes flying off...hmmm)
http://edge.i-hacked.com/make-processors-explode
Some components have lithium batteries in them, and you can make those overheat and explode by shorting out the appropriate pins (very dangerous when this happens).
Anyhow, the question isn't does it need cooling. The question is how hot can it get until it's performance/life degrades unexceptably, and how hot is it currently getting in a specific installation (if you're worried about that sort of thing). Since we're all running (or in my case will be running) installations that are different than everyone elses, I suspect that there are some that are fine with no additional cooling, and some that are being slowly cooked to death even with additional cooling.
This is why I intend to run a couple of extra wires through my firewall and into my engine monitor or fluke meter. I'll be able to temporarily install a thermocouple (or whatever) anywhere I want to answer just this sort of question if I ever feel like it. What can I say? I'm an engineer, and I like having telemetry.
This brings up a question. I have an RV wired pretty much according to Van's plans - thus a seperate switch for the alternator field. I've been starting the engine and THEN switching on the alt field. Is this harmful to the Van's internally regulated 60 amp alternator? Or should one turn on the alt. before you start cranking?
Thanks,
John Miller
Thanks,
John Miller
gmcjetpilot
Well Known Member
Great Question!!!!!!!!!!!!!!!
How does it work in a Cessna or Piper? We have all flown them right. Do you turn alternators ON and OFF separately? NO you usually turn the ALT ON with the master, before engine start and OFF with the master, after you shut the engine down.
In a car how do you start the engine and turn the alternator ON? You put the key in and turn it, first you get ignition than start. When you turn your car off you turn the key to off. As the engine revs up the alternator comes on line. When you turn the key to turn your car off, the alternator goes "off line" when it sense the IGN signal or no longer can maintain internal voltage as RPM decays. Don't get fancy with switch throwing. LET IT DO IT OWN THING, WHICH IS A SOFT START AND SOFT SHUT DOWN.
INTERNAL REGULATED ALTERNATORS are differnt than external regulated ones. They are really more sophisticated and designed to be ON at all times. The start up and shut down are automatic.
Internal VR's know how to handle coming ON line at certain voltages and off at certain voltage as RPM builds or drops off. Some have time delays and soft start (ramp voltage slowly). Not all are the same, and differnt ND alterantors have differnt characteristics. Now if the alternator is at high RPM and you tell it to "come alive" what will happen? It may deal with it. It may surge. It may just sacrifice itself to avoid a large volt/amp overshoot, burning out a component. There's NO advantage doing the extra (abrupt) step of cycling the alternator switch, none. The alternator takes so little HP to turn it is nil.
So don't turn the ALT on after start, turn it ON before cranking and leave it ON until the engine is shut down.
Anecdotal evidence/case studies: I have talked to two guys (one directly and another second hand) who had problems with their ND alterantor. The common thread was they turned there alterantors ON and OFF under load while the engine was still spinning.
In the first case the builder / pilot liked to throw switches and turned his 55 amp ND on after start and before shut down. The alternator was fine for awhile, but voltage started to become unstable. The voltage varied and dropped with load, which was above 14.5 volts (but below 16-17 volts). He also could NOT turn the alternator off using his panel switch for the ALT (IGN) as he had before. ****
****( The IGN wire on a ND alternator is NOT a FIELD wire. THE IMPORTANT POINT IS if the alternator regulator fails, the IGN wire may no longer control the VR, so you may not be able to shut it down? THE ONLY SURE METHOD TO ISOLATE THE ALTERNATOR IS TO PULL THE B-LEAD (CB). This definitively and without question will protect the aircraft and isolate the alternator, independent of anything. Some are using fuses on the B-lead and no CB as aeroelectrics suggest. I think its a bad idea. You loose a manual way to isolate the alternator.)
Also Van suggest not using an OV modules because they tend to damage alterantors. Since internal voltage regulators have OV protection already (internally, Yes they do), its not necessary in my opinion. Add on OV protection to an internally regulated alternator is a Rube Goldberg contraption, it adds weight, cost, parts and potential for nuisance trips. Again internal and external voltage regulation are different concepts, don't mix and match.
The second case the guy was flying and for some reason with all his electrics on he wanted to turn the alternator off to see if the battery would work? Really. Well when he turned the alternator back on the voltage spiked and weird things happened. He was able to turn it off again by turning the ALT switch off. The alternator was fried. What fried I don't know. I would love to get one of these abused alternators and see whats what.
What is happening? There is a big demand for power, the voltage is down to 12.6 volts or less, the alternator is spinning (fast) and has a large potential to produce lots of power, the alternator switch is thrown and the alternator surges and tries to ramp up the voltage fast. I have no exact failure mode since most guys do NOT do an analysis. Its only a theory on my part. Its based on the knowledge of the original intended application and the fact when you throw switches against how they where intended, they fail. People who leave them alone, have no problem. 1 + 1 = 2. (Note: If you get 1 + 1 = chair; stop reading).
HERE IS MY OFFER TO THE GROUP: IF THIS EVER HAPPENS TO YOU (regulator failure) PLEASE SEND YOUR REGULATOR TO ME. I HAVE CONTACTS AT A MAJOR AUTO ELECTRONICS COMPANY WHO MAKES VOLTAGE REGULATORS, AND THEY WILL DO A FAILURE ANALYSIS AND TEST IT USING SOPHISTICATED EQUIPMENT, X-RAY AND DISASSEMBLE THE REGULATOR TO SUB COMPONENTS TO FIND WHAT FAILED. Drop me a note and send me your damaged regulator. (There will be no charge to analyze your failed regulator, but you will have to pay to ship and will not get your damaged regulator back.)
HOW TO WIRE THE ND ALTERNATOR WITH INTERNAL REGULATION
Here is the way to wire it. When the master is ON, the ALT is ON. When the master is OFF, the ALT is OFF. For NON-normal conditions in the event of a failure of some kind, you should provide a way to turn the ALT off while the master is still on. This can be done with a pull-able circuit breaker (CB) or a "Cessna Style" split master switch. I don't don't like the Cessna switch, because its possible (easy) to turn the master ON without the ALT unknowingly.** At least you can't turn the ALT ON with BAT OFF which is Bad news.
I prefer a Double Poll Single Throw (DPST) toggle or Rocker switch that handles both the Master (BAT) and ALT; you know they will always be On or OFF together. In the event you need to shut the ALT lead OFF, use a pull-able CB for emergency ALT shut down. NEVER have the alternator on with the battery OFF. The DPST or Cessna Master will prevent this, and separate independent toggles or switches for the BAT and ALT are not a good idea at all, for this reason.
** (Always have a Hi/Lo volt indication (idiot light) if not the internal warning light provided by the alternator an after market warning device. Many engine monitors provide hi/lo volt warning. A volt meter is great if you check it all the time.)
Van does not recommend or show the use of the warning light (from what I hear). WHY NOT USE THIS GREAT FEATURE???? They just don't connect it to anything. That is a mistake in my opinion. Its also a fault indication, as well as high and low voltage indication. That was the way it was meant to be wired, wire it that way.
Most ND's have a plug with 2 or 3 wires: They all have IG or IGN, for ignition. The next common connection is "L" for light. This is the warning / fault light, which has varying functions between models. The next connector is "S", for remote voltage SENSE. The other wire is the large gage wire to the post, that is the output or B-lead.
Van also does not use the remote voltage sense (from what I hear). Some ND alterantors do not have remote voltage sense and use the b-lead or IGN wire to sense buss voltage. Van recommends you just tie the IGN wire and the S wire (sense wire) together (if you have a S wire, some don't). If you have a "S" wire and tie it to the IG wire, it works, but its not how it was designed.
The remote Volt-"S"ense goes direct to the battery and not the main buss. To be honest the "S" lead is more for cars that have long wire runs between the alternator, battery and fuse box. However its an input to the logic of the IC, and it uses that input to determine if things are OK. One big thing its checking for, is that the output (b-lead) is not shorted or disconnected, and it keeps the voltage at the battery more accurately controlled (as designed).
Pictures below: One is an alternator wired and another is expanded to show my no relay concept. Why have a BIG fat master relay sucking 3/4th amps of wasted power. Also most modern starters have their own relay. Why have two start relays? Some say you don't want the big battery cable HOT all the time. I think the risk is low, especially if you put a fuse on it (see my diagram). The other thing is starters with solenoids don't stick engaged like the old Bendix drive, so isolating the started is not critical.
One way to wire a ND alternator (error IGN wire should be 1 amp CB, 5 amps is not needed.) (Click to enlarge):
Here is an expanded diagram with the NO REALY concept. The master relay is a small solid state relay that only needs to handle 40 amps for example VS 400 amps. The emergency battery isolate is optional.
Even SkyTec Starters has Certified installations without a firewall Relay.
YES YES YES turn it on BEFORE cranking. BAD BAD BAD idea to do it after engine is running, in my opinion. This is why I take the time to write this and hope it helps you.jamiller said:
How does it work in a Cessna or Piper? We have all flown them right. Do you turn alternators ON and OFF separately? NO you usually turn the ALT ON with the master, before engine start and OFF with the master, after you shut the engine down.
In a car how do you start the engine and turn the alternator ON? You put the key in and turn it, first you get ignition than start. When you turn your car off you turn the key to off. As the engine revs up the alternator comes on line. When you turn the key to turn your car off, the alternator goes "off line" when it sense the IGN signal or no longer can maintain internal voltage as RPM decays. Don't get fancy with switch throwing. LET IT DO IT OWN THING, WHICH IS A SOFT START AND SOFT SHUT DOWN.
INTERNAL REGULATED ALTERNATORS are differnt than external regulated ones. They are really more sophisticated and designed to be ON at all times. The start up and shut down are automatic.
Internal VR's know how to handle coming ON line at certain voltages and off at certain voltage as RPM builds or drops off. Some have time delays and soft start (ramp voltage slowly). Not all are the same, and differnt ND alterantors have differnt characteristics. Now if the alternator is at high RPM and you tell it to "come alive" what will happen? It may deal with it. It may surge. It may just sacrifice itself to avoid a large volt/amp overshoot, burning out a component. There's NO advantage doing the extra (abrupt) step of cycling the alternator switch, none. The alternator takes so little HP to turn it is nil.
So don't turn the ALT on after start, turn it ON before cranking and leave it ON until the engine is shut down.
Anecdotal evidence/case studies: I have talked to two guys (one directly and another second hand) who had problems with their ND alterantor. The common thread was they turned there alterantors ON and OFF under load while the engine was still spinning.
In the first case the builder / pilot liked to throw switches and turned his 55 amp ND on after start and before shut down. The alternator was fine for awhile, but voltage started to become unstable. The voltage varied and dropped with load, which was above 14.5 volts (but below 16-17 volts). He also could NOT turn the alternator off using his panel switch for the ALT (IGN) as he had before. ****
****( The IGN wire on a ND alternator is NOT a FIELD wire. THE IMPORTANT POINT IS if the alternator regulator fails, the IGN wire may no longer control the VR, so you may not be able to shut it down? THE ONLY SURE METHOD TO ISOLATE THE ALTERNATOR IS TO PULL THE B-LEAD (CB). This definitively and without question will protect the aircraft and isolate the alternator, independent of anything. Some are using fuses on the B-lead and no CB as aeroelectrics suggest. I think its a bad idea. You loose a manual way to isolate the alternator.)
Also Van suggest not using an OV modules because they tend to damage alterantors. Since internal voltage regulators have OV protection already (internally, Yes they do), its not necessary in my opinion. Add on OV protection to an internally regulated alternator is a Rube Goldberg contraption, it adds weight, cost, parts and potential for nuisance trips. Again internal and external voltage regulation are different concepts, don't mix and match.
The second case the guy was flying and for some reason with all his electrics on he wanted to turn the alternator off to see if the battery would work? Really. Well when he turned the alternator back on the voltage spiked and weird things happened. He was able to turn it off again by turning the ALT switch off. The alternator was fried. What fried I don't know. I would love to get one of these abused alternators and see whats what.
What is happening? There is a big demand for power, the voltage is down to 12.6 volts or less, the alternator is spinning (fast) and has a large potential to produce lots of power, the alternator switch is thrown and the alternator surges and tries to ramp up the voltage fast. I have no exact failure mode since most guys do NOT do an analysis. Its only a theory on my part. Its based on the knowledge of the original intended application and the fact when you throw switches against how they where intended, they fail. People who leave them alone, have no problem. 1 + 1 = 2. (Note: If you get 1 + 1 = chair; stop reading).
HERE IS MY OFFER TO THE GROUP: IF THIS EVER HAPPENS TO YOU (regulator failure) PLEASE SEND YOUR REGULATOR TO ME. I HAVE CONTACTS AT A MAJOR AUTO ELECTRONICS COMPANY WHO MAKES VOLTAGE REGULATORS, AND THEY WILL DO A FAILURE ANALYSIS AND TEST IT USING SOPHISTICATED EQUIPMENT, X-RAY AND DISASSEMBLE THE REGULATOR TO SUB COMPONENTS TO FIND WHAT FAILED. Drop me a note and send me your damaged regulator. (There will be no charge to analyze your failed regulator, but you will have to pay to ship and will not get your damaged regulator back.)
HOW TO WIRE THE ND ALTERNATOR WITH INTERNAL REGULATION
Here is the way to wire it. When the master is ON, the ALT is ON. When the master is OFF, the ALT is OFF. For NON-normal conditions in the event of a failure of some kind, you should provide a way to turn the ALT off while the master is still on. This can be done with a pull-able circuit breaker (CB) or a "Cessna Style" split master switch. I don't don't like the Cessna switch, because its possible (easy) to turn the master ON without the ALT unknowingly.** At least you can't turn the ALT ON with BAT OFF which is Bad news.
I prefer a Double Poll Single Throw (DPST) toggle or Rocker switch that handles both the Master (BAT) and ALT; you know they will always be On or OFF together. In the event you need to shut the ALT lead OFF, use a pull-able CB for emergency ALT shut down. NEVER have the alternator on with the battery OFF. The DPST or Cessna Master will prevent this, and separate independent toggles or switches for the BAT and ALT are not a good idea at all, for this reason.
** (Always have a Hi/Lo volt indication (idiot light) if not the internal warning light provided by the alternator an after market warning device. Many engine monitors provide hi/lo volt warning. A volt meter is great if you check it all the time.)
Van does not recommend or show the use of the warning light (from what I hear). WHY NOT USE THIS GREAT FEATURE???? They just don't connect it to anything. That is a mistake in my opinion. Its also a fault indication, as well as high and low voltage indication. That was the way it was meant to be wired, wire it that way.
Most ND's have a plug with 2 or 3 wires: They all have IG or IGN, for ignition. The next common connection is "L" for light. This is the warning / fault light, which has varying functions between models. The next connector is "S", for remote voltage SENSE. The other wire is the large gage wire to the post, that is the output or B-lead.
Van also does not use the remote voltage sense (from what I hear). Some ND alterantors do not have remote voltage sense and use the b-lead or IGN wire to sense buss voltage. Van recommends you just tie the IGN wire and the S wire (sense wire) together (if you have a S wire, some don't). If you have a "S" wire and tie it to the IG wire, it works, but its not how it was designed.
The remote Volt-"S"ense goes direct to the battery and not the main buss. To be honest the "S" lead is more for cars that have long wire runs between the alternator, battery and fuse box. However its an input to the logic of the IC, and it uses that input to determine if things are OK. One big thing its checking for, is that the output (b-lead) is not shorted or disconnected, and it keeps the voltage at the battery more accurately controlled (as designed).
Pictures below: One is an alternator wired and another is expanded to show my no relay concept. Why have a BIG fat master relay sucking 3/4th amps of wasted power. Also most modern starters have their own relay. Why have two start relays? Some say you don't want the big battery cable HOT all the time. I think the risk is low, especially if you put a fuse on it (see my diagram). The other thing is starters with solenoids don't stick engaged like the old Bendix drive, so isolating the started is not critical.
One way to wire a ND alternator (error IGN wire should be 1 amp CB, 5 amps is not needed.) (Click to enlarge):
Here is an expanded diagram with the NO REALY concept. The master relay is a small solid state relay that only needs to handle 40 amps for example VS 400 amps. The emergency battery isolate is optional.
Even SkyTec Starters has Certified installations without a firewall Relay.
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pauldan181
Well Known Member
George,
So what does the IGN wire do if it does not provide the field voltage? You're saying that there are some failure modes where simply switching the master switch to BAT only will not kill the alternator? I have a 40 amp ND alternator and always assumed an unstable or overvoltage condition could be controlled with the master or pulling the "field" breaker. I for one am enjoying this thread
and want to understand how an alternator can produce voltage "by itself"
Thanks
Paul Danclovic
One vote for cooling
Ive been following this thread with interest. I have blast tubes to my alternator and both mags. Why? Because Tony Bingelis said to do it in his book on engines. 900 TT hours on this RV6A - I have only flown the last 250. Don't know if the blast tubes help but they make me feel better and I don't have any cooling problems with the o320. Steve in TX
Ive been following this thread with interest. I have blast tubes to my alternator and both mags. Why? Because Tony Bingelis said to do it in his book on engines. 900 TT hours on this RV6A - I have only flown the last 250. Don't know if the blast tubes help but they make me feel better and I don't have any cooling problems with the o320. Steve in TX
