J

jjhoneck

Well Known Member
When we bought our -8A last May, Tom Berge found that the ampmeter would occasionally drop to zero in flight. Sometimes resetting the voltage regulator circuit breaker would fix it, sometimes not.

Tom determined that the alternator was bad, and replaced it. This resolved the problem for a time, but then the on-again/off-again problem started again. This time, I replaced the voltage regulator.

Then on our way to OSH 2013, the ampmeter went to zero, and couldn't be reset. We shut off all extraneous electronics, and made an uneventful flight to Iowa. At OSH, I bought a Zefftronics regulator and installed it. We also found a blown fuse that fed power to the voltage regulator, and replaced it. We've been golden ever since.

Today the fuse feeding the regulator blew, and replacing it did NOT fix things. I took everything apart to troubleshoot the circuit, only to find my multimeter dead, too.

So, until I can get a new meter, I'm dead in the water. Since I live on an island, and it's Thanksgiving, I don't think I will be finding a meter until at least Saturday. Meanwhile, here's a synopsis of what we've done:

1. New alternator in May.
2. New automotive voltage regulator (the same model that was in the plane) in June.
3. New Zefftronics aircraft voltage regulator in July.
4. Replaced voltage regulator circuit breaker with a breaker/switch, that we leave in the off position during start up. (On the theory that we're preventing transient voltage spikes from reaching the regulator.)

Any theories what is going on here? It would seem that I've replaced everything in the charging circuit, yet I'm back at square one with no charging system.

Thanks in advance!
 
Normally the field circuit is protected by a 5 amp CB, a standard fuse will blow much sooner than a CB, however, it sounds like a shorted field in either the alternator or the wiring.

Not sure what brand of alternator you used but if you want to fix it once and for all, install a B&C alt and reg or a Plane power unit.
 
I changed everything in my system chasing a problem like this, finally changed the alternator switch and that fixed it, it was a B&C switch and the terminal on the back somehow got loose where it was riveted to the switch. Ordered a higher quality switch from Mouser. PN was 642-644H2
 
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170 driver said:
I changed everything in my system chasing a problem like this, finally changed the alternator switch and that fixed it, it was a B&C switch and the terminal on the back somehow got loose where it was riveted to the switch. Ordered a higher quality switch from Mouser. PN was 642-644H2
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Totally agree, the Honeywell Mil spec switches are among the best and can be found for very reasonable prices. It's the only kind I'll put in my panel.

http://www.peerlesselectronics.com/store/products/1TL1%252d4.html
 
170 driver said:
I changed everything in my system chasing a problem like this, finally changed the alternator switch and that fixed it, it was a B&C switch and the terminal on the back somehow got loose where it was riveted to the switch. Ordered a higher quality switch from Mouser. PN was 642-644H2
Click to expand...

The Carling switches that B&C sells are notorious for this problem. A bad switch can lead to an over voltage in the alternator circuit and the triggering of over voltage protection devices.

I'm not sure about the switch/breakers, but there's been a recall on them as well.

I would also check the integrity of the wiring... any connection should be suspect... including (especially) the alternator and engine grounds. When you get your voltmeter back online, test the wiring by turning the field circuit on (engine off!) and measure the voltage on your master bus and the voltage directly at the input to the regulator. If there is more than 0.25 volts difference, you have a problem with the wiring, switches or breakers.

Finally, even if everything checks out, I would make sure that your alternator diodes and the regulator have blast tubes to keep them cool. The continuing problems may be heat related.
 
The OP is a good reminder (myself included) to keep good wiring diagrams, and when ANYTHING reoccurs, (not just electrical) it is time to study more deeply. Hoping and waiting is a risky proposition.

Let us know what you find. Root causes are very helpful.

Thanks, HAPPY THANKSGIVING!
 
$27 Ford (1975 LTD with 400 engine) regulator from local auto parts store instead of expensive Zeftronics. And leave the alt field switch/breaker turned on all the time unless you're intentionally shutting it down due to a problem. Turning on the field coil while the engine is running is the electrical analogy to revving up your car engine to near redline , holding it there at high rpm and then abruptly moving the shifter from park to drive to take off. I've seen too many regulators get zapped by switching them on and off unnecessarily, and it's funny how all the experimental planes that I know of where the owners always leave the alt field switch/breaker on all the time never have charging system problems.
 
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LifeofReiley said:
My bet would be looking at the switch and the wiring... chances are the alternator is okay. Good Luck! :)
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Thanks for all the advice.

The Zefftronics voltage regulator has an LED indicator to show condition. It is dark, indicating no power to it at all. (Or, I suppose, it could be totally dead.)

One thing I tried before I had to quit for the day was to jumper across the in-panel voltage regulator breaker/switch. That made no difference -- I still had no power to the regulator.

That leaves the fuse (which is good), or the wiring. Or the regulator itself.

I hate electrical problems. lol
 
The switch I had that failed was the master/alt switch, it was intermittent and very hard to find the problem. It caused the voltage from the alternator to jump around all over the place when the engine was running. When checking it with the engine off, it always showed battery voltage when the switch was turned on. That's why it was hard to find the problem.
 
I went with a B&C alternator and regulator after having too much trouble with the Plane Power. After switching over I hooked the starter switch to the alternator so it wont start unless the field switch is turned on. (No spiking)
A switch will show voltage running through it although it will not take a load (amps) and there fore it wont work. Circuit breakers are the same way. It doesn't pay to have cheap parts.
 
UPDATE:

Well, I finally got a new multimeter and some time today to troubleshoot the problem.

First, I had juice at the voltage regulator fuse. Good.

Then, I had juice at the switch/breaker. Good.

Still had NO indicator light on the Zefftronics voltage regulator. WTF? It was clearly getting electricity.

So, I took the voltage regulator off the firewall, visually inspected it and reinstalled it. Bingo -- I get a green indicator light on the unit.

Bad ground? Must be. Maybe a little corrosion under the grounding wire? Who knows?

So, after consultation with my friend Tom Berge, I've run a secondary ground strap from the attachment bolt (that I had ground the VR to) directly to the grounding block mounting bolt that has the grounding strap going straight to the battery.

It just don't GET any more grounded. :D

Sadly, I didn't have time to test run it, but the green LED on the VR itself is a good sign, and I'm pretty sure that the problem is licked. We'll see how she runs tomorrow.

Thanks, everyone, for your help!
 
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