KHyde

I do have the ability to download the engine data. I will have to take a look at what is happening with the voltage. What was the outcome in your situation? Were you able to get reliable operations back somehow?

Good to know that 27V is low. I had no idea. Sounds to me from all of the comments that it’s most likely the voltage regulator. Very helpful, thanks!

Increasing RPMs seems to have no change in the voltage or on the amperes gauge. When I start up the gauge indicates a positive charge and the battery shows 27V. But then it just randomly drops off and the ampere gauge indicates in the negative and the battery shows in the 24V regime. The only thing that momentarily gets any sort of fluctuation in the ampere gauge is to cycle power on the alternator switch or reset the “Field/Alt 1” CB. I don’t recall seeing any lights on the indicator panel until I physically switched off the alternator switch while troubleshooting. The only big red warning was my engine monitor flashing red voltage numbers at me. The reason my hunch is heat related is because I have flown earlier in the mornings or on an afternoon that’s slightly cooler with no delays on the ground and have taken off with no issues throughout the flight. I’m just leery to take any family trips now, because it seems to be overall unreliable/unpredictable and I don’t want to get stuck off station or get into a self induced situation where I need the manual gear extension.

The voltage drops from about 27 when it’s charging to 24.3 and then slowly ticks down to around 24 while I try resetting CBs and what not to fix it. Sometimes it will charge for like a second after I flip the alternator switch back on but then it drops again.

Has anyone else experienced a failure of their alternator (or some other electrical culprit) due to operation on the ground before takeoff in hot conditions? We are operating in Texas and it’s regularly 100F in the afternoons. When I start up everything is operating normally, but before I can make it to takeoff the battery stops charging. Our mechanic initially couldn’t duplicate the error, but after further discussion with him, we decided that the alternator was getting heat saturated and breaking down. Well we have a new alternator and I went to take the plane out for a test flight post maintenance and everything was great until about 7 minutes after starting. At that point the battery stopped charging. We have a 1989 J model. Any suggestions or ideas on possible culprits of the problem would be much appreciated. Thanks!