Last Wednesday I taxied out for take off and when doing my runup I caught -25 amp discharge on the ammeter. I returned to the hangar to find that the connector attached to the output post had burnt in two. I replaced the connector thinking that would solve the problem....Wrong, after startup the ammeter went to +25A and increased with increase of RPM. I taxied back to runup expecting the amp gauge to drop gradually as the battery regained charge.

Not...raising RPM some to taxi I heard belt squeal...at runup it popped the 60A breaker...Taxi back to hangar. After talking to support at Plane Power (Hartzell) it was suggested that the alternator was bad. Hunting for an alternator I found one for $780. I took it to a starter alternator shop for testing and it tested good at 73 amps. It's being suggested that the regulator is bad? Any comments?

Sounds to me like the alternator is putting out too much power all the time, could be a regulator problem.

Plane power have a great troubleshooting chart here:

https://planepower.aero/wp-content/uplo ... nators.pdf

I have found their support to be excellent, they really go out of the way to help.They sent me a new regulator based on a chat with them. Super impressed.

yep, changed the regulator and it's seeming to work fine on the ramp

What brand was the failed regulator?

It is a Plane Power regulator.

If you keep having problems check your crimped connections by pushing in not just pulling on them. I had one that caused intermittent problems for two years before I found it. It would work loose and pop the field breaker, when I would look at stuff and tug to make sure wires/crimp was good it would reseat. DENNY

DENNY wrote:If you keep having problems check your crimped connections by pushing in not just pulling on them. I had one that caused intermittent problems for two years before I found it. It would work loose and pop the field breaker, when I would look at stuff and tug to make sure wires/crimp was good it would reseat. DENNY

Had something similar happen on my boat, crimps are good at hiding a few different odd failures, seems tight, I went to re secure the wires and pushing up on the wires caused that inward pressure and I was lucky enough to hear the radio blip on and then off and then on, I replaced it with one of those heat shrink crimps and that fixed it