rbridges Posted July 23, 2021 Report Share Posted July 23, 2021 I noticed my voltage dropped to 11.7-11.9 at the very end of my last flight; literally 60 seconds. Couldn't get alternator to kick back on. Put plane away but came back a few hours later and it worked fine. This was a week or so ago. Got up early for a flight, ran through preflight and everything looked good. Five minutes into the flight and alternator drops out. Nothing could get it back online. Showing 11.9v. Turned back around and took off cowling. No loose wires that I could see. I fired the plane up and alternator back online. Put cowling back on and then nada when I started it again. Called the local mechanic who will look tomorrow. I called joey Cole and he said to check the ground wire first. One interesting thing was crackling in my headset. Both radios. Normally they are very clear. Any suggestions? I don't want to throw good money replacing good parts. Quote Link to comment Share on other sites More sharing options...
rbridges Posted July 23, 2021 Author Report Share Posted July 23, 2021 Closer pic Quote Link to comment Share on other sites More sharing options...
PT20J Posted July 24, 2021 Report Share Posted July 24, 2021 You didn't say what you did to try to get it back online. If it runs and then goes off, it could be the overvoltage relay. Cycling the master will reset it. Here's a troubleshooting guide that may help. https://planepower.aero/wp-content/uploads/2018/02/Troubleshooting-Single-Engine-Externally-Regulated-Alternators.pdf Skip 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted July 25, 2021 Report Share Posted July 25, 2021 Sounds like… The voltage regulator stopped working or sending a signal to the alternator… check the field wire for any issues… -or- Alternator isn’t happy… check the belt to see if it has loosened up… -or- were the sounds rpm related? Often the voltage bridge made of diodes… can have a bad diode limit voltage output… PP thoughts about common challenges found around here… Best regards, -a- 1 1 Quote Link to comment Share on other sites More sharing options...
Yetti Posted July 26, 2021 Report Share Posted July 26, 2021 can't really see any of the wires and connectors. Go through the wiring to start with. My main lug fell off the wire when I unbolted it from the alternator. That sharp of a bend in a big wire is not a good way to do things. 1 Quote Link to comment Share on other sites More sharing options...
rbridges Posted July 26, 2021 Author Report Share Posted July 26, 2021 I ran some tests between the field wire posts. It's getting current, and the battery voltage looks solid; so I'm going to try replacing the brushes. IA will help me since this doesn't involve removing the alternator and is pretty inexpensive. If it works, it will buy me time to have it replaced down the road. 1 Quote Link to comment Share on other sites More sharing options...
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