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Alternator Reliability Poll

On your current airplane, how reliable is/was your alternator

  • I have used an automotive alternator and had no failures in its first 250 hours.

    Votes: 140 25.5%
  • I have used an automotive alternator that failed within the first 250 hours.

    Votes: 32 5.8%
  • I have used a Plane Power alternator and had no failures in its first 250 hours.

    Votes: 172 31.4%
  • I have used a Plane Power alternator that failed within the first 250 hours.

    Votes: 74 13.5%
  • I have used a B&C alternator and had no failures in its first 250 hours.

    Votes: 127 23.2%
  • I have used a B&C that failed within the first 250 hours.

    Votes: 3 0.5%

  • Total voters
    548
One driver of IR alternator failure rates in homebuilts is this:

The alternators typically used by homebuilders are designs originating in the 1970s through the 1990s. Few if any of these alternators have any kind of 'load dump' protection. Not a factor in cars; there's no way to do a load dump in that application. But homebuilders typically come from the certified world, where the alternator has a separate switch from the master. There are many ways to wire an a/c, and most of them provide ways to remove all loads from the alternator at the flip of a switch. Not an issue if the (external) regulator powers down with everything else and the field collapses. But with internal regulation, if the alternator is heavily loaded and all loads are instantly removed, the internal regulator can't track quickly enough to lock the output voltage at the setpoint. It can spike upward high enough to exceed the breakdown voltage of the semiconductors in the regulator, which effectively kills the alternator. Note that this is *not* a defective alternator design. It *is* defective operating technique by pilots. I have 'defectively' operated one that way myself, when I didn't know better.

I suspect that if you removed installation/operator errors, the IR regulator reliability numbers would approach the B&C numbers.

Charlie
 
In our recent REAL WORLD testing of a mid '90s Denso and Hitachi IR alternators, no damage was done with the battery completely disconnected, up to 60 amps load applied via a load tester and quickly taken on and off dozens of times.

IMO the #1 cause of IR alternator deaths is the substitution of inferior, aftermarket regulators, bearings etc. into an otherwise virtually bulletproof design.

I've shut off my Denso IR alternator in my 6A HUNDREDS of times over the last 15 years while it's outputting charge current- still working fine. https://www.youtube.com/watch?v=NvQRHuNpjss&list=UUiyBZlgDHg2GvQfelECCGoQ&index=15
 
Hi Ross,

I'm not sure we're talking about the same thing. Yours has a control terminal that actually tells the regulator to shut down; not all alternators from that era will shut down when power is removed from that terminal.

What I was describing is literally disconnecting the B lead while the alternator is heavily loaded. Some models will fail, some won't, and some might. Your model can obviously handle it, but not all will (or did).

Charlie
 
1992 Hitachi IR, loaded up to 60 amps output (full rated current), load removed, dozens of times, no damage, no battery connected to absorb any spike. Worst case scenario.

Speculation proves little. I've asked people in these alternator threads to actually do the tests (load, dump, temperature) and video it or at least document it so we can all learn something. Folks will have a lot more people listen to what they have to say when they present real world data rather than speculation.

Show us that this will fry X alternator and we'll certainly accept it. Until then, I remain unconvinced.

"The world is changed by your example, not by your opinion" Paulo Coelho
 
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Plane Power Alternator Output

I was checking old photos and videos to verify the voltage displayed in my Dynon D120.

I never close monitored the voltage reading, just spot checks during normal operations, and i could swear that it was steady at 14.1 or 14.2V all times!!

But, i was wrong... when watching some videos recorded 4 years ago (Note: my alternator, battery, and all other electrical components are all the originally installed, never replaced and all of then are 6 years old!!) i got surprised to realize that the voltage "floating" between 13.6 and 14,2V occurs very often!!!

Despite it's not a desired reading, my battery is 6 years old (concorde) and still works fine!!!!
Never had problems or difficult to crank the engine, even with more than 30 days flight interval!!!

So... this "Gremlin" appears to be innofensive!!!

In any case, i'll run a complete connections check up... and keep flying!!!
 
Auto Alternator Reliability

My experience is with a $100 ND 55 amp internally regulated auto alternator that had been rebuilt by Bosch. It is the model that was originally on the 1987 Suzuki Samirai. It was rock solid at 14.2 volts until around 400-450 hrs and then the voltage started varying somewhat. I took it off, took it to an "off road" alternator shop and they replaced the bushings (which really did not need replacing but since we had it apart . . .) and the internal regulator (they probably installed a cheap one)--at the outrageous expense of $65. It was again rock solid but only for around 100 hrs and again some (+ or - 1 volt) voltage variation. I replaced the entire unit with another $120 ND 55 amp unit rebuilt by Bosch and all is good again. I would conclude that the quality of the internal regulator is critical to the reliability of the unit. At only $120 for the unit I intend to replace it or rebuild it myself (using quality parts) every 500 hrs. BTW, I do not have a blast tube to the unit.

YMMV

Cheers,

db
 
ND IR 40 amp. Ran it 1300 hours, 10 years with no problems. Overhauled engine and decided to put a new ND IR 40 amp in. It's been working about 350 hours so far. Old one is spare. Blast tube cools the back end where regulator is, another tube blowing on stator section.
 
Blast Tube

Probably should install a blast tube to the IR on the alternator---Heat and cheap parts be the enemy!!

Cheers,

db
 
A followup on, previously reported, post #136 in this thread, failure of PP 60Amp IR alternator, at 115 hours. I shipped the failed unit to PP for warranty. Today I found out their determination of failure was due to "The stator epoxy was loose". Agent said sometimes bubbles get into the epoxy and it leads to early failure. I had never heard of that one. To their credit, they are sending me a new unit, even though it is slightly outside the warranty period.

Greg Novotny:D
RV-14a N14ZP
Tacoma Narrows
 
A followup on, previously reported, post #136 in this thread, failure of PP 60Amp IR alternator, at 115 hours. I shipped the failed unit to PP for warranty. Today I found out their determination of failure was due to "The stator epoxy was loose". Agent said sometimes bubbles get into the epoxy and it leads to early failure. I had never heard of that one. To their credit, they are sending me a new unit, even though it is slightly outside the warranty period.

Greg Novotny:D
RV-14a N14ZP
Tacoma Narrows

Thanks for the followup Greg. It is good that PP actually looked at your unit, and good to know that they are using epoxy. I wonder if they are using epoxy for stator-to-case for retention or impregnated windings to get better cooling and prevent wire shorting issues. A few years ago PP had issues with the stator motion failing the (stators) attachment wires.
 
A followup on, previously reported, post #136 in this thread, failure of PP 60Amp IR alternator, at 115 hours. I shipped the failed unit to PP for warranty. Today I found out their determination of failure was due to "The stator epoxy was loose". Agent said sometimes bubbles get into the epoxy and it leads to early failure. I had never heard of that one. To their credit, they are sending me a new unit, even though it is slightly outside the warranty period.

Greg Novotny:D
RV-14a N14ZP
Tacoma Narrows

That is exactly the same thing they told me when mine failed at 100 hrs.
 
PP 60A failure under 250 hours

I posted on another thread the symptoms of my alternator failure. Anyway, my Plane Power alternator that came with the RV-10 FWF kit failed at 25 months old and 245 hours. It was a broken stator wire.

It's currently at an alternator shop to see if they can repair it but if they can't I'm going to B&C. I'm not spending my money on another plane power since it looks like 1 in 3 are failing under 250 hours. I fly my RV all over western North America and reliability is paramount when crossing the rocks.
 
I had an interesting conversation this morning with Hartzell/Plane Power. A quick summary:

They have no insight whatsoever in regards to the design, other than is starts out as a Nippondenso alternator. The manufacturing rights were purchased from the previous developer, Plane Power. +

The product is not even produced by Hartzell in house. It is produced by a vendor and shipped to Hartzell essentially complete.

There are no service and repair procedures, nor parts. A warranty is simply a new unit.

They are totally unaware of field failure data.

They have no plans to investigate the high failure rate of this product.

I have a 60 amp version PP that was provided with my RV-10 kit. It now has over 500 trouble free hours. I am leaning heavily towards a proactive replacement with the B&C, although it will require installing a voltage regulator.

I had a similar experience with them. But here's the rest of the story.
At just over 500 hours, my PP 60 amp alternator began struggling to provide voltage under load. With everything running my voltage would drop to near 13v.
I pulled out the paper work on my alternator, the stuff I received from vans, and low and behold it said to check/rebuild the alternator, and it listed a part number for the rebuild kit!
I called pp (hartzell) and they had no idea what I was talking about. I then plugged the part # into the aircraft spruce search engine. A full page of results came out, With no way to tell which one was the one for me.
Finally, I called the nice folks in Ft Worth Aero performance. The gentleman was also quite perplexed. He said he would get back to me.
He did! He was able to figure out which overhaul kit I would need, and offered to sell it to me or let me buy it from aircraft spruce, as apparently they are partners. The overhaul kit is basically one unit which incorporates the brushes and the regulator. This was a very simple rebuild. My alternator is working fine again. I have the part# and info on the rebuild kit if anyone wants them. No guarantee it will be compatible with your model though.
 
pp alternator rebuild

I had an interesting conversation this morning with Hartzell/Plane Power. A quick summary:

They have no insight whatsoever in regards to the design, other than is starts out as a Nippondenso alternator. The manufacturing rights were purchased from the previous developer, Plane Power. +

The product is not even produced by Hartzell in house. It is produced by a vendor and shipped to Hartzell essentially complete.

There are no service and repair procedures, nor parts. A warranty is simply a new unit.

They are totally unaware of field failure data.

They have no plans to investigate the high failure rate of this product.

I have a 60 amp version PP that was provided with my RV-10 kit. It now has over 500 trouble free hours. I am leaning heavily towards a proactive replacement with the B&C, although it will require installing a voltage regulator.

I had a similar experience with them. But here's the rest of the story.
At just over 500 hours, my PP 60 amp alternator began struggling to provide voltage under load. With everything running my voltage would drop to near 13v.
I pulled out the paper work on my alternator, the stuff I received from vans, and low and behold it said to check/rebuild the alternator, and it listed a part number for the rebuild kit!
I called pp (hartzell) and they had no idea what I was talking about. I then plugged the part # into the aircraft spruce search engine. A full page of results came out, With no way to tell which one was the one for me.
Finally, I called the nice folks in Ft Worth Aero performance. The gentleman was also quite perplexed. He said he would get back to me.
He did! He was able to figure out which overhaul kit I would need, and offered to sell it to me or let me buy it from aircraft spruce, as apparently they are partners. The overhaul kit is basically one unit which incorporates the brushes and the regulator. This was a very simple rebuild. My alternator is working fine again. I have the part# and info on the rebuild kit if anyone wants them. No guarantee it will be compatible with your model though.
 
The alternator shop that I mentioned in post #163 was able to replace the stator and all was good with the PP alternator. That was until last week when the voltage regulator failed in it and triggered the over voltage protection circuit.

I just finished installing the B&C 60 amp alternator and LR3C-14 external voltage regulator. It was an easy retrofit. It was more than I wanted to spend but the failure rate of new plane power units is unacceptable.
 
I just replaced the PP alternator on the -10 with a B&C 40A (to go along with the pad mounted B&C backup alternator).

We lost the PP alternator on a night XC ~10PM.

Sent it back, turns out it was a mechanical failure of some component of the front bearing components (per their report).

<150h on the unit.
 
Front bearing failures are typically related to over tightening the belt. Was the belt tension set using one of the approved methods?
 
Yes - and I actually checked it with a torque wrench as per the install manual.

I?m one of those that always reads the directions and tries to do stuff like that by the book...
 
Cheap alternator

I installed a copy of the Nippon-Denso equivalent to part # 14684 one year ago and after 99 hrs the bearings are gone. The local shop is replacing the cheap Chinese bearings with better ones.

And no warranty support from the supplier.

Alternator Bosch, model AL430N. (You guessed it, made in China.)

Michel
 
Our local electric motor shop stopped repairing alternators a few years ago. They couldn't afford the warranty claims. The biggest issue was voltage regulators, but they had bearing problems as well.

Obviously OEM's have better quality control, even if they come from China.
I would take a used one out of a low mileage wreck over any clone or rebuild.

My choice was brand "B" for a couple of other reasons, including the summary of this reliability poll.
 
My first plane power failed after 100 hours no additional cooling. It was replaced under warranty by an other one and I added a cooling hose. Failed after 150hours.
Replaced with an other unit last week... let's see...
 
$32.11 free shipping

https://www.amazon.com/Stator-Leads-27-8209-27-8200-340-52005/dp/B07HFGR9PR

Ensure movement of stator inside housing and of 4 stator leads are eliminated with high temperature sensor safe silicone. Unipoint and PP should have been ensuring this on their $500+ alternators. Its easier to blame out of balance props and lack of cooling blast tubes. DIY or take your airboat alternator to one of the few remaining alternator shops and spend 1/6.

Stator

Replace OEM(s): Denso

For: Nippondenso

Used On: Denso Alternators

Amps: 60 Amps

Amps Draw: 58 Amps

Amps Low Output: 60 Amps

Condition: New

Lam Stack ID: 3.031in / 77mm

Lam Stack OA Width: 25mm

Lam Stack OD: 3.937in / 100mm

Lam Stack Thickness: 1.051in / 26.7mm

Mounting OD: 100 mm

Slots Count: 36 Slots

Specification: 77X100

Voltage: 12 Volt

Weight: 1.66 lbs / 0.75 kg
 
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About 8 years ago I switched from the Van's 35a alternator to a Nippondenso, the one for a 70's Honda. I wired around the built-in regulator and retained my B&C external regulator. I had 2 failures caused by broken stator wires (covered by warranty). I stabilized the stator and the wiring as mentioned in the previous post and it's been fine ever since.
 
Question about the guts . . .

The stators have a shoulder bolt that secures them to the housing. Are they loose? PP uses 2 of them but the design allows 4 to be used. More likely it is rotor orbit or rotor balance that initiates the vibration. Or the bolts were not properly torqued. I found a screw protruding from the belt end bearing retainer on one. It just was not screwed all the way in. A QC issue to be sure.

Question to you guys, what did the SRE (slip ring end) bearing look like? Did it have two plastic rings embedded in the outer race?

VPBO_7-nb_idNdyTh7aAEnsZxAArAMwb60C7Q8tgroNWobjnoVpUtJ_al0XQ2oy5CL1qqhpJwLMp5WmHNdWGYTGiLXJfuvmO_vPdueMymbIZ-wJy0WBi7SAgYsc9Ll-OTsriS0LupkTNGGUCAEXXIvh-07C3pEOSlS32REcUqpedMw70d8qZu7zN7CE02oLPkOif_wcvsG73tpo-Mjq-vAqEzq7SFjObblgr8_q1A6LyfCUsgYRQlj323k8tQPyDhRc2w346igA3-aFgkJgEpvWDlWJYdVb82spQSMd3oWVZBNEexoMO1Mq4rfHVnJ_JT8_RWh6I9pcMsinSlRstw_I8E9IOLM981Mynpc6VlhVFJKum6LXa7WtKJFwikZ8Z6Id8tFxC6uWW40KPJMealLvLct3JVKYE308tN4D5jMe6HAYkibz7RNwzEF9osACPuK6h-_K5QLxP6dCTbVR_Z6kBpize34NXGbuidm96m-EyiFrWNuQ6Mq73K_zGc5uaDWw_o3f3FtbuMWI8-62Jx4koz0aWQGI4-3UTp5h9tkooopyuEaJorjYXrjZy5M0czANjdcbxhcHIION5Qm27peud3FNKDP75ZtCz862_v2h_90WB23cWUTKoLkc3Xom1gfFrzDpjTDzEHTQGZWsKd065O_G6Q88nWBBHRR7yPx-KeptZ8KZA5yA=w600

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The stators have a shoulder bolt that secures them to the housing. Are they loose? PP uses 2 of them but the design allows 4 to be used. More likely it is rotor orbit or rotor balance that initiates the vibration. Or the bolts were not properly torqued. I found a screw protruding from the belt end bearing retainer on one. It just was not screwed all the way in. A QC issue to be sure.

Question to you guys, what did the SRE (slip ring end) bearing look like? Did it have two plastic rings embedded in the outer race?

VPBO_7-nb_idNdyTh7aAEnsZxAArAMwb60C7Q8tgroNWobjnoVpUtJ_al0XQ2oy5CL1qqhpJwLMp5WmHNdWGYTGiLXJfuvmO_vPdueMymbIZ-wJy0WBi7SAgYsc9Ll-OTsriS0LupkTNGGUCAEXXIvh-07C3pEOSlS32REcUqpedMw70d8qZu7zN7CE02oLPkOif_wcvsG73tpo-Mjq-vAqEzq7SFjObblgr8_q1A6LyfCUsgYRQlj323k8tQPyDhRc2w346igA3-aFgkJgEpvWDlWJYdVb82spQSMd3oWVZBNEexoMO1Mq4rfHVnJ_JT8_RWh6I9pcMsinSlRstw_I8E9IOLM981Mynpc6VlhVFJKum6LXa7WtKJFwikZ8Z6Id8tFxC6uWW40KPJMealLvLct3JVKYE308tN4D5jMe6HAYkibz7RNwzEF9osACPuK6h-_K5QLxP6dCTbVR_Z6kBpize34NXGbuidm96m-EyiFrWNuQ6Mq73K_zGc5uaDWw_o3f3FtbuMWI8-62Jx4koz0aWQGI4-3UTp5h9tkooopyuEaJorjYXrjZy5M0czANjdcbxhcHIION5Qm27peud3FNKDP75ZtCz862_v2h_90WB23cWUTKoLkc3Xom1gfFrzDpjTDzEHTQGZWsKd065O_G6Q88nWBBHRR7yPx-KeptZ8KZA5yA=w600

a8_PGmM2iRyeu8COVpUrXR2faigjYAGDdxHfQ_f9FIWtVRFFzMEMthFT0b6pZR2o-sbeh_g6dkXT-o3322FvXP5L_wdrEHaF5iL13ok9wQW-LoZbt_MvS02pPD15CYBolqz_wvnY_cApuvUUGvPXh1NFzh2O0rsxBdJ7n6pXgHbGNPcKT7IoMjXBV_Ml0EW2S1ZTPPuvwtNqfz5FPEjmbRRQR4MSWuG3WRWuqMBlV3ybpAXfc2N5JavQXqHXYZFGSrmxg_SJJ6MIqlVRSXcWhu6Pri53MF6ImY9vH3przkQy8sgtYubct-7qvy0-n_Nycd-oseE01D2wDta-IhapmDcznswym4IAqqTM6NjswOF2Xu9ziNxO03hzjJomKby0gDvHiiUgB9GPgW0r4-R0MUIMEFAeGY5tP_sdaRQsx3rAiXmxQmV4tWwlWJD6hsigEhSS7QAWoa1crIp0tyJ9TcE7KEfSHanDaxw2ED8Ctx4GlK1TRorKYP5ej2dQOFuCuf4xzbTQu3nIF5q-AvX6QAaXui-8oWIHkB8kruz6qxAdIJgUx2O0IU2YhoMgJ2_VhxyBiJ21N000op45DOIUrlTvXOw8CYM4Q5phmuE-RfZ7xyukDZblselaQT_KIvKjUGYRf2ABKinzx6C9x2GH5q6Wt7OsbSXX6EfD1HBuPVZ95jRbwsQAiu8=w600

Yes, mine were loose. Star washers now installed.
 
I haven't read every post, but...

regardless of the reasons for failure, there are enough respondents to the OP to say with some level of confidence that:

Out of all respondents reporting failures before 250 hours,

[*]Automotive Alternators failed at a rate of 28/148 or 18.9%
[*]Plane Power Alternators failed at a rate of 58/201 or 28.9%
[*]B & C Alternators failed at a rate of 3/116 or 2.6%

Based on this survey, why would anyone buy a Plane Power alternator?
After that, I'm left with a choice of an automotive alternator that costs less than $100, is lifetime warranted, and has about a 1 in 5 chance of failing in the first 250 hours or,

I can buy a B&C (without a lifetime warranty?) for about 8 times as much,
knowing that the odds are very good that I'll make it past 250 hours without having to do a changeover.

I see that many respondents listed the time that they got out of their hardware before failure. This is a useful survey. Too bad everyone didn't list time to failure - that would have given us more useful information for decision making.

BTW, I'm now on my fourth automotive alternator, with total airframe time around 1300 hours. If I had a little extra cash laying around, I'd switch to B&C - my failures always seem to occur when I'm on an instrument FP and out of state.

Terry, CFI
RV9A N323TP
 
While the 250 hour threshold in the survey provides useful data, I don't find that amount of time particularly satisfying - 250 hours isn't very long, and I would hope our alternators could, on average, exceed that time substantially. The 250 hour time already gives B&C a big advantage, but I wonder what the inverse would be - say, at what number of hours have 75% of the Plane Power alternators failed, and the same info for B&C. That might be even more startling. In my community of pilots - both experimental and certified, I constantly hear of PP failures. That said, while this is only a single point of data, I have a 60A B&C that is now 20 years running and 1550 hours, and it has not had any problems. I did have a charging outage (on an IFR flight, of course!) that turned out to be a broken field wire, just outside the alternator at the connector. Which brings up a point - The B&C alternators have two actual field spades in the connector, to which I now have the field connected to both for some redundancy, as well as running silicone fine mutli-strand wire, with a little bit of slack, from the last solid support point to the alternator field connector, to hopefully resist vibration damage.
 
Our Altercator

Plane Power installed 600 hours and 8 years ago. RV-6, Lyc. O-320-D1A, fixed pitch Catto, blast tube from the front right baffle. Still working great!
 
Here’s my experience with a Plane Power backup alternator. It went off line in flight. Inspection showed it dangling from the cable. It took less than 100 hours for the threads in the bolt on adapter to fail. Short fasteners in cast aluminum from the factory. The B&C unit I replaced it with has a one piece nose, not an under engineered bolt on adapter.

i-t7dGZd3-XL.jpg


i-JhbjN9v-L.jpg


i-PgCDntb-L.jpg
 
My B&C installed

Here is my B&C installed. I cant imagine changing this in the field once engine installed. I made sure the mounting bolts were torqued to spec, but no more.

It seems Lycoming engines were designed when mechanics’ salaries were cheap, and Lycoming probably also owed a crowsfoot factory.
 

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Here’s my experience with a Plane Power backup alternator. It went off line in flight. Inspection showed it dangling from the cable. It took less than 100 hours for the threads in the bolt on adapter to fail. Short fasteners in cast aluminum from the factory. ...
Wow - that must have been a really sick feeling to see. The shaking on a typical lycoming is pretty intense, so is the vibration, so anything hanging on there with leverage is going to need to be very well designed and implemented.
 
switching to B&C

My PP alternator failed at 450 hours, which is apparently a long and happy life for one of these guys.

I did have ample warning the unit was failing. In flight the steady state voltage dropped from the typical ~14V down to 13.2 over a period of a few dozen flight hours. On the flight it died, it was dipping below 13V, then suddenly dropped to zero... alas, never to recover.

My installation did not include a blast tube. I don't recall it being in the FWF instructions when I was doing my install (2015ish). I worked with PP to troubleshoot the unit (including installing a new brush assembly and verifying the rotor resistance).

Currently waiting on my B&C LX-60 alternator and LR3D-14 regulator. This poll helped convince me to make the switch. Even though retrofitting the regulator will take a little extra work, it's worth it if the installation is more reliable.

I asked B&C about a blast tube, and they stated it is not needed (or recommended) for most installations, including the -7A.
 
PP

60 amp PP installed when my 10 was new in 2011
Going on 800 hrs without issues. Blast tube directed at the back.
I did install a Monkworkz back up a few month ago and I also keep a spare PP on the shelve.
 
A few months back, my 1000 hour Denso failed 20 miles from my destination at KRWI. I had no time as I was headed out on a 3 day trip in the corporate jet so I asked the local maintenance shop if he could help. He said he was familiar with the RV-10 and would have no problem.

The next day he called and said the bearings were done and that NAPA had the same alternator for $70. He installed it and the total bill was just over $200 including labor.

Convenience, reliability, cost, I am good to go with automotive electrons.
 
60 amp PP installed when my 10 was new in 2011
Going on 800 hrs without issues. Blast tube directed at the back.
I did install a Monkworkz back up a few month ago and I also keep a spare PP on the shelve.

"... Blast tube directed at the back ..."

Per a Hartzell engine that looked at my installation, this is probably THE most important thing one could do for a long life of the alternator. Either cooling the electronics when under the cowl, or better yet, REMOVING them (external regulation) is key to success.

As a result, I changed my blast tube from blowing onto the SIDE of the electronics to making a "U-turn" and blowing FORWARD towards the BACK of the electronics.

I think that if they made a version of the PP alternator as we currently have but WITH their external regulator box (similar to the B&C in functionality), their experience reliability would go up a lot more.
 
"... Blast tube directed at the back ..."

Per a Hartzell engine that looked at my installation, this is probably THE most important thing one could do for a long life of the alternator. Either cooling the electronics when under the cowl, or better yet, REMOVING them (external regulation) is key to success.

As a result, I changed my blast tube from blowing onto the SIDE of the electronics to making a "U-turn" and blowing FORWARD towards the BACK of the electronics.

Yeah...

https://vansairforce.net/community/showpost.php?p=1720446&postcount=10


https://vansairforce.net/community/showpost.php?p=1720591&postcount=22

While speaking with a respected vendor a few days ago, I suggested he produce blast tube shrouds, basically a cup to fit (or replace) the rear cover, with a spigot for the tube. Cooling efficiency would be vastly improved.
 
"... Blast tube directed at the back ..."

Per a Hartzell engine that looked at my installation, this is probably THE most important thing one could do for a long life of the alternator. Either cooling the electronics when under the cowl, or better yet, REMOVING them (external regulation) is key to success.

From the poll results, the auto alternator (I assume many with IR) seem to do just fine.
 

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Now if we could just get a highly skilled, intelligent, and handsome electronics guy to tell us how to modify a Denso regulator so it provides OV protection....;)
 
Now if we could just get a highly skilled, intelligent, and handsome electronics guy to tell us how to modify a Denso regulator so it provides OV protection....;)

I might argue that a denso VR has OV protection built in. Once the VR hits the target voltage, it starts dropping field current all the way down to zero if it must to keep it at or below the target. If the alternator is STILL over volting at this point, the only savior is something that disconnects the B terminal. A failing VR can cause over volts, but due to the failing nature of the VR in this scenario, it should not then be relied upon to stop the issue. An exception is the B&C that has a separate OV protection circuit inside the VR box. I believe they use the simple knuckles circuit. IMHO the best option is an ext VR setup with a simple knuckles OV crowbar on the VR's power source. Cheap and effective. Can then also buy a quality VR, such as B&C or a transpo to get past the PP reliability issues. IR alternators are easy to convert. We did this all the time on sailboat engines to get ext VR's with charging intelligence. Sterling was the top brand in that area and provides great conversion instructions.
 
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This Denso Alternator will accept the PP Regulator and provide over voltage protection, successfully installed and bench tested.


Voltage is only showing 13 on your bench.. mine with IR maintains 14.2 at a 3 amp or so charge rate, does get to 13.8 ish volts if the battery was down and its charging at a higher rate, than it gets back to 14.2 14.3 once the batt is back up
 
I don't understand the obsession with an all-in-one package. Just buy an externally regulated alternator, a voltage regulator for $20, a over-voltage module for $40 (tho someone above mentioned B&C doesn't have it any more, but that it can be made easily?) and be done with it. The beauty of alternator, VR, and OV being separate is that if anything fails you just swap out the offending part at very minimal cost or effort.
 
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Voltage is only showing 13 on your bench.. mine with IR maintains 14.2 at a 3 amp or so charge rate, does get to 13.8 ish volts if the battery was down and its charging at a higher rate, than it gets back to 14.2 14.3 once the batt is back up

The photo happened to be shot when the load was increased to 50 amps pulling the output voltage down to 13 volts.
 
I don't understand why folks want to take a professionally engineered piece built by one of the most respected vendors in the world, who has produced MILLIONS of them over 4+ decades and modify them.

Do you folks know something Denso doesn't? You think that modern cars, which are WAY more electronic than an RV would survive a major OV event? You think the auto OEMs don't have that covered?

I've been working on car stuff, lots of Toyota in my repair shop years past, for over 4 decades. Haven't seen an OV event yet on a Denso alternator. Nor have I heard of one in a car. I still have friends in the industry. They haven't seen one either.

I'd like to see a poll on how many here have experienced an OV event on a genuine Denso alternator fitted with genuine Denso parts inside.
 
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Really big finding here . . .

Voltage is only showing 13 on your bench.. mine with IR maintains 14.2 at a 3 amp or so charge rate, does get to 13.8 ish volts if the battery was down and its charging at a higher rate, than it gets back to 14.2 14.3 once the batt is back up

The photo happened to be shot when the load was increased to 50 amps pulling the output voltage down to 13 volts.

Remember this is a 40 amp alternator. It may well be reaching saturation. I venture a guess that a 60 amp will do the same if asked for power beyond its rating. I am not seeing this as a problem, but an inherent characteristic.

What is a big deal is the PP regulator and brush block fitting the 93mm OD stator of this alternator - - a really big finding thanks to Don.

This allows us to have a near direct replacement without a rewiring job, and get the quality of a 1000 different elements in the OTS Denso.

Also, this part number alternator is a standard for Caterpillar/Perkins engine. This means it has the beef to handle the belt loads and the high g loading of being bolted to a diesel engine - this is added confidence although YMMV.
 
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Do you folks know something Denso doesn't? You think that modern cars, which are WAY more electronic than an RV would survive a major OV event? You think the auto OEMs don't have that covered?

I think we would like to know HOW they have it covered.
 
That would be something to ask Denso. I don't know what they are doing inside their IR, just that it seems to work as we just don't see many modern cars with fried electronics. That's either due to the fact that they almost never OV in the first place or the OV protection within the IR is really good.

I'll put out some info here though on the popular OV devices that many are using- LR3D and VPX Pro. We had a customer with both on his RV and he suffered 2 separate OV events, likely through load dumps. These failed to protect multiple devices- glass panel, autopilot, ignition controller and even defrost fans- they all fried. The TCW battery was damaged and the main battery also bulged the case but still was functional.

You may not be as protected as you think with these devices.
 
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I think we would like to know HOW they have it covered.

Not fully sure about the automotive, but they were better than my former employer. The devices, like ECM's, had to handle up to 50 line attached volts from attaching welders and the like and down to 6-7 volts when starting cold. They have to be pretty bullet proof or get fried. All machine electronic devices had the same requirements.

Also high electrical fields (RFI EMI/EMC) can generate resonance at low amps and burn through silicon. I forget but it is a pretty high volts-per-meter potential Devices test validated to the standards in a chamber.
 
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