Request Thoughts on Elec System Situation

[Jeff_S]

Hello all. Still going through the shake-down period on this J. I'm working with my A/P on this and also discussing with the prior owner and his A/P, but sometimes I know the wisdom of the multitudes can help. Here's the deal:

1) Plane comes down from Nebraska to ATL two weeks ago. It gets flown heavily for 15 hours over two days, and then sits in ATL for 10 days until I can get back to it.

2) On Sunday I get in for my first solo, battery is dead. But jump start from the FBO gets it going, ammeter/voltmeter seems normal, no annunciater voltage lights, everything seems fine in flight, and battery has charge after shut down. Next day, my A/P checks the battery and it's already down to <10volts so we suspect it's just gone bad...three years old after all.

3) Newly charged battery goes in yesterday, and now there is a definite pulse on the ammeter and a pulsing whine through the headset that both increase with RPM. (Prior to the new battery, there was a constant whine through the intercom that increased in pitch with RPM...so that's been there, but now it pulses instead of whines.) But still, no annunciator lights, and the JPI gauge shows the battery at 14.3-14.6 with the engine running.

I know electrical system issues can sometimes be quixotic. With my general understanding of things, I would say this sounds like an alternator or voltage regulator problem. There is a log entry for work done on both two years ago, with a new voltage regulator put in.  But what would cause a drain on the battery in a dormant state? (Yes, double checked that both dome lights are off.)

Anyway, thoughts are welcome. I went through something similar on my Warrior once and we tried everything else first, and then put in a new alternator and that solved the problem.  But the hunt is on again for a cause...

[Cruiser]

read this

http://www.donmaxwell.com/publications/MAPA_TEXT/Fluctuating%20Ammeters/Fluctuating%20Ammeters.htm

[piperpainter]

Just a thought......I know I have a transponder that makes alot of noise and my beacon that makes a pulse(slow but no doubt a pulse) I have gotten used to it and only notice if its gone or when a friend mentions it.

Anyway, if the noise occurs only when everything is one then maybe you should shut everything off, see if its there then turn things on one by one to find out what is actually making the noise. Maybe its something in the avionics that is now working correctly since it's getting proper voltage continously unlike before.

my .02Cents for the day!

[Jeff_S]

Good points all...the usual suspects always apply. The tip from Don Maxwell about the Master switch corrosion seems like the easiest and cheapest way to start.

 

[jlunseth]

I had a similar problem in my plane.  The pulsing I mean.  It turned out that when the battery voltage dropped to low, the strobe lights could be heard through the speaker and there was some noise (whine) in the headsets.  Am having the alternator checked.  It is possible that you have bare wires to ground somewhere in the aircraft.