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Alternator Fooled Me

Mystery solved with the flickering light on my PlanePower alternator.
That darned light has been flickering faintly for at least 100hrs, even though it has always produced good power. The alternator has been bench tested but not disassembled
The alternator finally quit at 261 hrs, so it went to our local shop and $120+tax later it is back in service.
The fix was a new stator. Turns out the stator is not keyed into position, but merely clamped by the case screws. In this case there was slight rotational movement as evident from the chafing marks, and over time this broke the connections to the stator. Needless to say the new stator is fixed, I believe with a Loctite product.
No more flicker.
 
Following on from Dan's issues - and rather than start a new thread - I thought I'd seek the collective help of the VAF Brains Trust on a nearly identical issue.

For the last 20 or so hours, I have been trying to work out what is causing my alternator to be constantly hunting in output. The alternator is a single PlanePower FS-14B, one of those internally-regulated ones that mounts on the vacuum pad.

From my "Running a tank dry" video, it also shows the problem I'm having, with the voltage and amperage fluctuating between 14.5-14.8V and 8-16 amps.
https://www.youtube.com/watch?v=PSexkSe8gl8

I flew again today after running a series of resistance checks on the B-lead connections, the master contactor connections and amp shunt fittings, all were secure and no variation to the resistance was shown during the tug tests. I'd previously removed the 3-pin plug and noted a small amount of corrosion on one of the female pins, though nothing I'd class as troubling. Today, I removed the 3-pin plug and also removed the 2 female pins from the housing, and squeezed them down slightly before reinstalling it. Next step is to replace the plug and pins in their entirety.

Of note, when the battery is low, ie for the first 10-20 minutes of flight, there are no problems, it charges normally and indications are rock-steady. When the problem manifests itself, turning the alternator OFF drops the indicated amperage to 0 and battery volts to around 13.5-14.0 as you'd expect. Reselecting the alternator several minutes later shows normal charging until the current drops, then the problem recurs.

From what I've done so far, I figure:
  • I don't have any loose fittings (the only one left to check is the Alt Field pin onthe VPX-end socket)
  • The problem is 'actual', not an 'instrumentation' problem.
  • The problem is internal to the PP alternator
  • The problem is not vibration-related as it is too regular in its' cycling.
I can't see a problem doing so, but rather than replacing the alternator, is there any reason I can't install a separate external voltage-regulator in addition to the internal one in the PP unit?

So...Does anyone have any ideas?
 
Check ground connections?

Sounds like you checked all of the positive connections. Did you also check the ground connections from the alternator all the way back to the battery and instrument panel?. I suggest you disconnect all of them, clean them and reinstall.
 
Following on from Dan's issues - and rather than start a new thread - I thought I'd seek the collective help of the VAF Brains Trust on a nearly identical issue.

For the last 20 or so hours, I have been trying to work out what is causing my alternator to be constantly hunting in output. The alternator is a single PlanePower FS-14B, one of those internally-regulated ones that mounts on the vacuum pad.

From my "Running a tank dry" video, it also shows the problem I'm having, with the voltage and amperage fluctuating between 14.5-14.8V and 8-16 amps.
https://www.youtube.com/watch?v=PSexkSe8gl8

I flew again today after running a series of resistance checks on the B-lead connections, the master contactor connections and amp shunt fittings, all were secure and no variation to the resistance was shown during the tug tests. I'd previously removed the 3-pin plug and noted a small amount of corrosion on one of the female pins, though nothing I'd class as troubling. Today, I removed the 3-pin plug and also removed the 2 female pins from the housing, and squeezed them down slightly before reinstalling it. Next step is to replace the plug and pins in their entirety.

Of note, when the battery is low, ie for the first 10-20 minutes of flight, there are no problems, it charges normally and indications are rock-steady. When the problem manifests itself, turning the alternator OFF drops the indicated amperage to 0 and battery volts to around 13.5-14.0 as you'd expect. Reselecting the alternator several minutes later shows normal charging until the current drops, then the problem recurs.

From what I've done so far, I figure:
  • I don't have any loose fittings (the only one left to check is the Alt Field pin onthe VPX-end socket)
  • The problem is 'actual', not an 'instrumentation' problem.
  • The problem is internal to the PP alternator
  • The problem is not vibration-related as it is too regular in its' cycling.
I can't see a problem doing so, but rather than replacing the alternator, is there any reason I can't install a separate external voltage-regulator in addition to the internal one in the PP unit?

So...Does anyone have any ideas?

Sounds like the voltage regulator or it's connections/wire inside the alt case. The VR inside the alternator is replaceable and would suggest starting there. The fact that everything works well under high load would indicate there are no wiring issues. Lots fo these PP's have stator failures. I am not an expert on alternators, but would investigate if the early stages of stator failure could cause the fluctuations. Doesn't seem likely, but don't know.

You can also check for problems with certain loads. I see current fluctuations routinely, due to devices like strobe power supplies and wig wag lights, etc. However, typically a good VR will keep the voltage swings to about .1 volts during these current swings.

Larry
 
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Intermittent PP high alternator voltage

My voltage would go high, over 15 volts intermittently. I found my negative battery cable was not tight at the battery. I torqued it to 80 inch pounds which solved the problem. Also A/S has the PP regulator in stock. It is a drop in assembly and includes the brushes. I purchased one as a spare.
 
You can't install an external 'in addition to' the internal regulator. You could mod the alternator to use an external, but there's no way to use two at once; the regulator controls field voltage, and whichever regulator sends the most voltage will be the one controlling alt output. (And it's a total unknown whether one reg would destroy the other, or possibly have mutual destruction.)

It's worthy of consideration that current varying by 100% while voltage varies by <4% is pretty unlikely, unless you have a *load* that's intermittent. It's also noteworthy that voltage seems to rise as current is going up, by a *lot* more than a half volt could drive, and voltage falls as current is falling.
DC circuits are pretty much a straight power formula: V=I*R. So with round numbers:
14V*8A=112 Watts
If voltage goes to 14.5 & the load isn't changing,
112/14.5=7.73A
Or viewed another way,
14.5V*15A=217.5 Watts

If the numbers are real, your power is varying by almost 100% while your voltage is varying by <4%.

What leads you to conclude that the changes are real and not instrument error?

What kind of battery, a lithium? Any lead-acid battery would not show anywhere near 14V with the alt off line.

Long distance troubleshooting is pretty hard, but I'd suspect instrument error, and the previous post about negative side issues would be the 1st place I'd look. Not just tightening connections, but opening them, cleaning mating surfaces, and reinstalling. Then I'd get the VPX out of the circuit, at least for testing purposes. (process of elimination)

Charlie
 
Sounds like the voltage regulator or it's connections/wire inside the alt case. The VR inside the alternator is replaceable and would suggest starting there.
That's my initial thought as well. BMW_X6M mentions Spruce as a source, but I'm struggling to find the page for it.

lr72 said:
You can also check for problems with certain loads. I see current fluctuations routinely, due to devices like strobe power supplies and wig wag lights, etc. However, typically a good VR will keep the voltage swings to about .1 volts during these current swings.
(Un)Fortunately, my RV is minimally equipped, I have the electric fuel pump, VP-X, Xcom VHF, 1x Dynon SkyView with their transponder and a pair of servos. No lights at all, and the only relatively high-current device is the flap motor.

My voltage would go high, over 15 volts intermittently. I found my negative battery cable was not tight at the battery. I torqued it to 80 inch pounds which solved the problem. Also A/S has the PP regulator in stock. It is a drop in assembly and includes the brushes. I purchased one as a spare.
I didn't think to check the negative cables you know...I will do that next week on my RDO's, though of course it makes sense, a high resistance connection = low volts, VR attempts to compensate, yadda yadda. The regularity of the fluctuations is what's got me beat. And as above, could you point me to the Spruce spare VR? I'm struggling with my Google-fu...:eek:


You can't install an external 'in addition to' the internal regulator. You could mod the alternator to use an external, but there's no way to use two at once; the regulator controls field voltage, and whichever regulator sends the most voltage will be the one controlling alt output. (And it's a total unknown whether one reg would destroy the other, or possibly have mutual destruction.)
That eliminates a simple fix then, unfortunately... :(

rv7charlie said:
It's worthy of consideration that current varying by 100% while voltage varies by <4% is pretty unlikely, unless you have a *load* that's intermittent. It's also noteworthy that voltage seems to rise as current is going up, by a *lot* more than a half volt could drive, and voltage falls as current is falling.
DC circuits are pretty much a straight power formula: V=I*R. So with round numbers:
14V*8A=112 Watts
If voltage goes to 14.5 & the load isn't changing,
112/14.5=7.73A
Or viewed another way,
14.5V*15A=217.5 Watts

If the numbers are real, your power is varying by almost 100% while your voltage is varying by <4%.

What leads you to conclude that the changes are real and not instrument error?
My conclusion came about based on nothing more than the fact the readings are stable at high-current draws, and as current flow tapers off the fault appears. I was thinking at times of low current demand, a small variation in resistance (sensed voltage really) would cause a relatively big change in voltage output. Thinking about this a bit more, I should pull up the AltField current on the VP-X screen to see what it is doing, while this is going on.

charlie rv7 said:
What kind of battery, a lithium?
Yes, a Shorai lithium, though it is around 4 years old now.

rv7 charlie said:
Long distance troubleshooting is pretty hard, but I'd suspect instrument error, and the previous post about negative side issues would be the 1st place I'd look. Not just tightening connections, but opening them, cleaning mating surfaces, and reinstalling. Then I'd get the VPX out of the circuit, at least for testing purposes. (process of elimination)

Charlie
I will do that, and report back next week. Hopefully the weather cooperates!:)
 
PP alternator

Reading through the thread and catching a hint that the PP alternator is somewhat of a copy of popular auto alternator. Brought in my alt to an auto part supplier and asked if he could check it out and he wanted to know what kind of auto it was out of before he could attempt to put on the test stand. Thought it should be easy to test generically, but guess not! Any ideas out there on the PP AL 12E160/C and how to identify it's roots. Originally bought from Van's. Shows 13.7 volts when it's working but had it as low as 10 volts when I started to shut things down to get home. 10 minutes of running on the battery only I decided to try it and there it is charging at 35A. Checked connections at both ends but haven't dug into the field connector ( bought another one in case ) the Alt has 100 hrs on it!!

Thanks
 
Skip the retail auto supply, and take it to an auto-electric shop (rebuilder). There should be at least one nearby, if you're in a major metro area.

They will likely be able to ID it without the auto source.
 
Reading through the thread and catching a hint that the PP alternator is somewhat of a copy of popular auto alternator. Brought in my alt to an auto part supplier and asked if he could check it out and he wanted to know what kind of auto it was out of before he could attempt to put on the test stand. Thought it should be easy to test generically, but guess not! Any ideas out there on the PP AL 12E160/C and how to identify it's roots. Originally bought from Van's. Shows 13.7 volts when it's working but had it as low as 10 volts when I started to shut things down to get home. 10 minutes of running on the battery only I decided to try it and there it is charging at 35A. Checked connections at both ends but haven't dug into the field connector ( bought another one in case ) the Alt has 100 hrs on it!!

Thanks

I took my Vans supplied PP 60 A alternator to a local alternator/starter repair shop. They tested it and told me they suspected a rectifier failure which took out the built in regulator (I had a runaway alternator issue taking out the field fuse).This happened after 4 hrs of operation. Cost $100 and had it back in a week. They said the parts were common auto parts. Been running fine for the last year and half and 230 hrs.
 
Any ideas out there on the PP AL 12E160/C and how to identify it's roots.

They're made by Unipoint, a budget division of Bosch, at locations in Taiwan and mainland China. Appears to be a copy of a Denso alternator, model unknown. The regulator is a modified version of a Unipoint Denso replacement, modified with a jumper wire and some hot glue.

No, I'm not kidding.

Unipoint%206621.jpg
 
Patrick,
I see you're located in Calgary. Al at Probuilt on Ogden road was able to source a Nippon denso stator and rectifier for my 60A Plane Power back in November. I think it cost me $150 for the repair.
 
colin,
Thanks for that! I brought it into Bowness Auto Parts and had it tested. Put out 14.6v. I'll go over the wiring again when I put it back in this weekend. I did find another connector on line and ordered it, just in case.
Patrick
 
Fooled me too . . . . . .

There I was, flying along, minding my own business, and I get an "EIS VOLTS" warning. Uh oh, losing an alternator.

Pulled the cowl when I got home. Internally regulated Plane Power, so basic diagnosis is simple. If you have bus voltage at the B lead, and bus voltage at the red wire, the problem is internal to the alternator. I had good volts, so off it came.

Quick inspection inside the back cover didn't turn up anything obvious. Pulled the regulator/brush assembly. Brushes look good, commutator is smooth, about 3 ohms through the rotor (field) windings, no short to ground. Hmmm. pull the rectifier screws, stand up the stator connections, and they check good too. Ok, doesn't leave much, so I get a new IC regulator from a buddy and installed it. Back on the airplane it goes....and doesn't charge. Whatttt?

Recheck field power, and the B lead, and make sure it's not an indication problem by cycling the EFIS from main buss to backup battery. All good. Out of time, got a business trip in the AM, so I buy a new, identical 60 amp Plane Power (Hartzell Engine Technologies is right here in Montgomery). I'll get the old one shop-checked and overhauled as necessary, then I'll have a spare.

Out to the airport, bolt on the new alternator, do a run-up....and it doesn't charge either.

Finally I go into Old Car Guy mode. Forehead slap; I've seen this before, and besides, there isn't much left. I walk around to the front, pull out the three prong field/indicator plug, and look real close with a 10X magnifier. Nope, hadn't missed a burned socket, and they all looked clean, but just the same, I squeezed the sockets closed just a bit, and plugged it back in.

Yep, that was it; a runup said I was now blessed with many vigorous electrons.

Problem appears to be unsupported wire where it exits the back of the plug. The little square sockets in the plug are not held tightly by the plug body, so the socket and wire can vibrate around. Eventually wear/debris/corrosion/loss or spring pressure makes the connection(s) intermittent or non-conductive.


. . . . but I had long ago read this thread - so I should have known better :mad:. I'll spare everyone the details of all the actions I took that DIDN'T help and just cut to the chase. Here's what I had after pulling the three terminals out of the connector body.


697V24ppwA0wiDqclHLu2kB05OzZ5hKygIZxuk65mw9i-Iefggfyw24Xstqohnies_xNIDsn54Gekf5PcN_r_l7h4GvMhmmAOXzqL2R9IZZpYhN1YsXduecAFkA5-5B48nyFIFihfUiihDAnUY7HdkwNxhdg6Uck_gGqIfqQdyAfYf0t7mMv201te16WRiju8Roeik3aNovPat27gq0gw3YurUdwoYiV_jDQYzKFRPk5ip1lykDURKormH49uebXkCflJ1rkiGtu1c3OkGlxmo8Ax0yDpZlm7dLOXE-FFiwST1AgHHX_gk6aExw4TNnv3osFQKhtT5lyIxAfrWP_zXCU6w4hLsVJBfgaph2YygX3O7_4KjP2E-_2sqJW5osqXa_TzOS1JqTbPnq4OT17Z9_u2rjEtVIbTjcpH5IWrorz6YgeAwIvsKluXhATfyhIRNfrraHlXk70DJ-bQAcjG9po1LKMrOakOWkKwGmeTLM9-lkb92krOq3ccL6RvMGJMMMlCINRciMkza_5YFspSTM32N5IyWUB-9eOXZry2tKrH5I0P7Mwai1sSHJyoSS98QqR9uuEpp_V0KfPMcXuPEHhF5rt8W6QcAlknWEkGjloMoy080fS_DHbI0_AUouExTSfXXFKdi-Q2--Bh0wFssK7M9BkKrSAoDEHcq4u0tVr1ADwi5JfThCU9LdskYcVX6dhbz7TcD4dlYj-1CSndCVu09FoMaRtmHYwB6l3ahGMmcEsUGBmQiFcglFCwEcshwcFbUnrK1TtfbRZvtV6kOLYIC22_G5HApNoFbvm-OzdLWKpCD5i1tNxPvacHtvC0CTtOdIZG5eUbCJhWt-KPHbHoJ-jjMzueFp14dZHcp20kfXsjQ_K8qFNZx_8TO3owb_-KqDKSQ1CErYTvjvMpbNu-hdNa45cISPb1O3YeGjMzA=w1023



The expression "hanging by a thread" comes to mind. It took about 900 flight hours for this to occur. Crimped all new terminals on after first sliding the little Silicon seals over the wires (shown by someone else in a previous post). These look like they will do a dandy job of giving extra support.
 
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My standard check of Plane Power alternators (problem solving and at every annual) has become...

(1) Remove from the engine, clamp the pulley in a solid vice with the regulator end pointed up, and rock it back and forth to feel for clearance at the rear bearing. Found another bad one yesterday; 350 hours, lots of clearance. And no, the belt was not too tight, the reason for bearing cavity wear previously offered by Hartzell. This belt was actually quite loose, certainly at or below the low end of the worn belt slip torque value.

(2) As detailed in this thread, take a detailed look at the terminals in the plug. Even if the wires have not fatigued due to no backshell fixation, the contact surfaces can be fretted. Look for black oxide debris.
 
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My standard check of Plane Power alternators (problem solving and at every annual) has become...

(1) Remove from the engine, clamp the pulley in a solid vice with the regulator end pointed up, and rock it back and forth to feel for clearance at the rear bearing. Found another bad one yesterday; 350 hours, lots of clearance. And no, the belt was not too tight, the reason for bearing cavity wear previously offered by Hartzell. This belt was actually quite loose, certainly at or below the low end of the worn belt slip torque value.

(2) As detailed in this thread, take a detailed look at the terminals in the plug. Even if the wires have not fatigued due to no backshell fixation, the contact surfaces can be fretted. Look for black oxide debris.

Dan, if you take this one apart, can you send a photo of data plate and the SRE bearing OD? Thanks
 
One of the wires fell out of the Plane Power plug due to a poor crimp! This was during assembly prior to flight.
Stewart Willoughby, 6
 
Wire

<snip>

(2) As detailed in this thread, take a detailed look at the terminals in the plug. Even if the wires have not fatigued due to no backshell fixation, the contact surfaces can be fretted. Look for black oxide debris.

</snip>

The real fooler on this one was that there was no evidence of any fretting and the wires seemed secure when yanked and wiggled from the back side. It wasn't until I removed the wires/terminals from the connector housing that the problem became clear.
I never had a permanent hard failure of the alternator - just a barely flickering lamp with an occasional solid light and the accompanying voltage drop. It would always clear itself up at some point.
 
Well I’m chasing down a similar issue. Went for a flight the other day (first one since fall and the annual CI). Plane Power alt E160/B and VPX driving a dynon skyview single screen. Got the flickering (dimming) screen with intermitent “aircraft power lost” message. On the VPX menu page on the screen the “main” (alternator) power was jumping all over from 5 to 15 Amps and the VPX showing putting out power from 1-9 Amps. The green check next to EFIS would disappear and re appear. Amps on the boost pump, radio, and Pri Alternator would drop to 0. All wiring seems to be secure…..I’ll check the connections on the VPX itself tomorrow. But it would be great if it’s a regulator plug issue like a lot of you have been seeing. Dumb question though….what kind of extractor would I need to pull the wires from the plug?
 
Well I’m chasing down a similar issue. Went for a flight the other day (first one since fall and the annual CI). Plane Power alt E160/B and VPX driving a dynon skyview single screen. Got the flickering (dimming) screen with intermitent “aircraft power lost” message. On the VPX menu page on the screen the “main” (alternator) power was jumping all over from 5 to 15 Amps and the VPX showing putting out power from 1-9 Amps. The green check next to EFIS would disappear and re appear. Amps on the boost pump, radio, and Pri Alternator would drop to 0. All wiring seems to be secure…..I’ll check the connections on the VPX itself tomorrow. But it would be great if it’s a regulator plug issue like a lot of you have been seeing. Dumb question though….what kind of extractor would I need to pull the wires from the plug?

It is for sure a rectangle, maybe .040 X .080" and round the end. I will measure when I get my tool from the hangar.
 
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