cycling voltage problem

andrew phillips · #1 06-17-2009, 04:35 PM

I have the plane power internally regulated alt on my IO-360. The voltage has started to vary between 10.2 and 13 volts. It goes up and down over about a 20 second period. This occurs during cruise flight conditions. I have tried playing with all the electrical stuff in the cockpit - no change. I looked under the cowl and all the connections seem tight. Bad ground was first thought but the time period and the repetitive nature of the problem are making me think that's not it. Battery is PC-680 1 year old and never given me a sign of any problems.

L.Adamson · #2 06-17-2009, 04:55 PM

In our case (not my plane), it was a loose crimp where the B-lead attaches to the alternator. Good voltage on the ground, but dropped when in cruise and under load. Even though some of the strands were still connected to the crimp connector, it had been arching.

L.Adamson --- RV6A

turbo · #3 06-18-2009, 05:02 AM

check your power input from alternator to main bus post. i had a lose connection there and had the same problem.

andrew phillips · #4 06-18-2009, 01:48 PM

Sure enough the nut on the post of the main fuse block was loose. It's raining so I didn't test the fix but I am pretty confident that was the problem!

THANKS you saved me hours of troubleshooting!