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Help Wanted: Alternator Issues

hevansrv7a

hevansrv7a

Well Known Member
I originally installed the alternator that came with my 7A QB. It lasted about 90 hours. I replaced it with the same specs but a Bosch re-man. It lasted about 100 hours and recently failed in flight. I replaced it with the identical product. It worked for about 2 hours (1 flight) and failed on start-up for flight #2 this morning. I took it back for a refund and ordered a Plane Power AL12-E160 from Van's this evening. I have a blast tube for cooling the back of the alternator where the internal regulator sits. Both failures this time - and I think last time - were the regulator. I tension the belt as per my friend the A&P, so that it can hold about 18 ft-lbs of torque before slipping. I don't know what my temps are in that area, but my CHT's are always very reasonable - low to mid 300's usually and sometimes even high 200's when flying slowly as in practice IFR work.

So is it A] just crappy auto-store parts B] incredibly bad luck or C] something wrong that is killing alternators? It would be good to know before installing the Plane Power unit.

I use a Cessna split master and the wiring is pretty much as per plans with the wiring harness from Van's.

Any help or suggestions would be welcomed.
 
A+B

My not so humble opinion (after doing the same as what you did) is that there are two alternators suitable for IMC use..Plane Power and/or B&C.

OK I know this sounds a little bit like "airplane stuff only for airplanes" Mantra but believe me this is not where I'm coming from.

Flying in IMC is serious business a failed alt can be a very scary situation which the $400 or so you spent on the PP unit will seem like mouse nuts if it ever happened.
Most rebuilt alternators are marginal quality, its just not a good place to save money.

The line voltage is controlled by the alternator..pretty much the only thing that could destroy them is if the B lead was grounded and the subsequent fire would be a small indication something wasn't right....:)

Check the PP unit instructions when you get them and check your wiring as you do the install..You reaLLY can't go wrong.

Make sure you have properly made crimps or soldered connections that connect to the alt..I have seen way too many where the wire could be pulled out of the crimp with fingers.

Frank
 
I will say this... and not argue the point any further in this thread but, for some reason... different than the old school separate regulator set-up, internal regulators do not like to be fired up after engine start. Your procedure? My alt is on from start to finish.
 
One other thing

Make sure you have a good ground from the alternator case to the battery -ve post.

This is normally achieved by bolting the alt to the engine block (no painted brackets or other insulation) with the PP cad plated brackets then a beefy ground lead from the engine block to the battery.

Now you ask "what idiot would paint his home made alternator brackets?"

Lets just say I know a friend of a friend who's GNS 430W kept resetting itself because of the noise generated by the intermittent connection between the alt case and the engine block..This guy chased that fault for some time.

But I really CAN'T remember his name..I just remember thinking what an IDIOT this guy was at the time..cough.Cough.;)

Frank
 
agreed

LifeofReiley said:
I will say this... and not argue the point any further in this thread but, for some reason... different than the old school separate regulator set-up, internal regulators do not like to be fired up after engine start. Your procedure? My alt is on from start to finish.
Click to expand...

just like in the car!

Frank
 
Nope, that's not it..

My start up procedure is to turn on the master switch - both sides at once. Only then do I engage the starter with the key. My ground to the engine from the alternator is good according to my digital VOM. The alternator field wire has full voltage with engine not running. Resistance in that wire is nil, too.

I do, sometimes, turn on only the battery side in order to operate my glass panel, but I don't engage the starter when I do that.

It is not possible to turn on the alternator field (left side of the switch) by itself. That is why I used the Cessna master just like I had in my C-150.
 
Yep!

frankh said:
just like in the car!

Frank
Click to expand...

Since I removed my alternator switch, I've not had a failure.
I use a regular 55 amp auto alternator (internal fan and internal regulator).
STRICTLY VFR!
 
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Reman...

Junk... most do not last past there warranty. Buy a NEW alternator, not from CHINA and you should be Okay... :) I would also take out the alt switch and do away with it as it is not necessary.
 
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Mel said:
Since I removed my alternator switch, I've not had a failure.
I use a regular 55 amp auto alternator (internal fan and internal regulator).
STRICTLY VFR!
Click to expand...

I don't see how it would help you IFR either... maybe a good fire??? To me the alt switching is totally BS.
 
LifeofReiley said:
I don't see how it would help you IFR either... maybe a good fire??? To me the alt switching is totally BS.
Click to expand...

Sorry! I meant that I might not use a regular auto alternator if IFR. I would still not have the switch, regardless.
 
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I don't understand about the switch

I don't understand what you mean by taking out or leaving out the alternator switch. Do you wire it to be on at all times like a car? But cars don't have master switches. I am a dunce about wiring, so please clarify. Thanks.

What is bad about the way I have it ? I assume the switch you are talking about leaving out is the left side of my Cessna split master.
 
Why would the switch matter?

Sounds plausible that the switch isn't necessary. But why would it affect the life of the internal regulator? Why would energizing it after start make a difference?

Jim Sharkey
 
jsharkey said:
Sounds plausible that the switch isn't necessary. But why would it affect the life of the internal regulator? Why would energizing it after start make a difference?

Jim Sharkey
Click to expand...

Yes! Once upon a time, we had a very regular poster here on VAF who went by the moniker "GMCJETPILOT" and wrote extensively on the topic....search for his posts and you'll get quite an education (whether you want it or not)!

I've had two alternatorson my -8, one Van's original (lasted about 300 hours), the second from NAPA, in 950 hours - second is still going strong after NEVER switcing it off while rotating....might be just superstition of course....;)
 
Thats funny!

Ironflight said:
Yes! Once upon a time, we had a very regular poster here on VAF who went by the moniker "GMCJETPILOT" and wrote extensively on the topic....search for his posts and you'll get quite an education (whether you want it or not)!
Click to expand...


..:)...Actually George IS a very well informed individual to his credit..but it still made me laugh!

Frank
 
Ya

I miss GMC. Always fun to read the posts, learn a bit and watch it quickly digress. I enjoyed his posts thoroughly and I personally wish he was still around. A smile a day ... makes life good.

Just saying... Osh in a week, OOOOOHHH BABY.
 
FWIT, I've never had a Nipon Denso based alternator fail.

I think B&C is Nipon. It was in a previous airplane and as far as I know it is still cranking out the amps after 10 years.

The Subby came with a little 35 amp Nipon that was bullet proof and under rated, it could carry much more than 35 amps.

Now it is with the Plane Power unit from Vans. It too looks a lot like a Nipon.

So far, so good with it. :)
 
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jsharkey said:
Sounds plausible that the switch isn't necessary. But why would it affect the life of the internal regulator? Why would energizing it after start make a difference?

Jim Sharkey
Click to expand...

It's a surge factor you might say... instant taking on of a load. A quality unit may handle it for a while, this cheap stuff will fry in 200 hrs or so and leave you stranded looking for a another replacement, most of the time a cheap one... I've gotta go weekend type of a situation.
 
LifeofReiley said:
It's a surge factor you might say... instant taking on of a load. A quality unit may handle it for a while, this cheap stuff will fry in 200 hrs or so and leave you stranded looking for a another replacement, most of the time a cheap one... I've gotta go weekend type of a situation.
Click to expand...

I don't go for that "theory" either. I know someone with hundreds of hours on Van's alternators who always turns on the alt switch after startup.

As to my own plane, I still have that B-lead relay that was supposed to be part of a over voltage protection system for internally regulated alternators. I disconnected the over voltage module that was suppose to short the alt lead breaker. The reason was nusense tripping of the B-lead relay under load, which could cause alternator failure---- or so they say.

Anyway, to make the long story shorter......... I somehow turned off the alt switch on a long cross country. It was long enough to bring the voltage down to just over 11 volts. Doing this, actually disconnected the B-lead at the same time. We've heard stories that if the alt switch is turned off, that it won't actually disable the alt field in an internal regulated alternator. But is this fact? I'm not so sure.

Regardless, no damage was done with the alt switch off and the B-lead disconnected by the relay. The engine restarted and everything was charged back up in 20 mins or so. That's been around 70 hrs ago.

I actually like the idea of a B-lead disconnect in case of a true runaway alternator. That's why I've left it intact.

L.Adamson --- RV6A
 
Two failures with the Nippon Denso that came with the firewall forward kit and now a plane power is running strong in our bird. The Nippon has been overhauled and is in a box for quick shipping by a family member any place that I might become stranded. These things just don't like to turn as fast as we turn them.


As for George... He was my favorite to read even though he was quick to make me aware that anything I ever knew was wrong. I miss that. A few weeks ago I checked in on the Yahoo Groups Experimental Avionics Forums and George was there in the middle of a heated debate and far more colorful than ever. I was spellbound and read every last well informed spanking that he was serving up. He goes by GMCJETPILOT there also.
 
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Sorry Folks...

As I stated before, I'm not going to argue this. Being in the fleet maint. business for years with commercial trucks, refrig units, cranes lifts etc... on trucks that have battery source reserves with alternator power... for many years, I've seen this issue too many times. These little electronic plastic internal regulators can't take much abuse. And yes, you might be the lucky one... count your blessings. One problem is the speeds we turn these alternators too.

Better yet, install a 4" pulley! Landoll proved that!
 
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