Electrical Woes :(

M

mike newall

New member
1979 7GCBC, replaced the battery 4 months ago as one cell was down. Prior to that the previous battery lasted about 15 months.

Symptoms are poor starting, no power in the battery, even after a flight. Ammeter is showing a charge when the engine is running. If you bench charge the battery, all problems go for about 3 weeks.

Replaced the master solenoid which had no effect - suspected a constant drain when stood.

I remember someone having a similar snag last year and have tried a search but can't bring it up.

Anyone got any good troubleshooting tips as we don't quite know where to start.
 
Mike,

I've had issues with both my solenoids in the past year. It doesn't sound as if this is your problem. When I was having my trouble, I'd press the start button and all I heard was a click or a couple of clicks. Half the time it would start and half the time it wouldn't. Anyway, I ended up replacing the starter solenoid on the firewall and thought I fixed the problem. Well a couple weeks later, the same thing happened. I ended up changing the master solenoid and haven't had a problem since. Those solenoids are so cheap, it should almost be done as preventative maintenance over a period of several years. I believe mine were originial.

Jon
 
It sounds like something is draining your battery down while the airplane is sitting. That's easy to check. Disconnect one of the battery leads, with the master switch off, and put an ammeter between the battery cable and the battery terminal. It should read zero current flow. Airplanes tend to sit moreso than automobiles so it won't take much of a drain to kill the battery.

Another possibility is a poor connection somewhere that is not allowing the full power of the battery to go to the starter which would make it appear to be a weak battery.
 
I just reread your post and the part about not having any power even after flying makes me suspect either the alternator isn't charging properly or poor connection in the alternator/battery circuit or even a starter that is drawing excessive current which would give the symptom of not enough battery power.
 
Jon,

You describe our symptoms exactly - I will change the starter relay as well and see if that helps.

We have tried the leakage test and all seems well, I guess we can check the alternator output - bit scary with the engine running but I am sure we can sacrifice a mechanic or two in the process :mrgreen:

There is something strange about this aeroplane - the electric turn and slip affects the radio - worse when I fly fast, better when I fly slow.

I will wait until things warm up a bit and then have a good go at it, system by system I think.

Keep the suggestions coming chaps.
 
I bought my 7KCAB about a year ago. It had several "issues" with the electrical system. We got rid of probably the original voltage regulator and over voltage box, and then reworked the system to comply with service letter 418A that can be found on the ACA website by clicking on the "technical" button. Since the work was done, it has been problem free regarding any electrical gremlins.

Greg B
 
If the ammeter shows a charge, as you said, then does it show a big charge for at least a minute or so after a start? If no, you might have a bad engine to airframe ground.. Do you have an electric clock? Take out the fuse and see what happens. The clock was the problem with my wife's airplane.
 
Don't forget your avionics. The digital display radios use a small draw to retain the stored frequencies for your convenience when you start them up next time. So after sitting idle for a prolonged time it's not uncommon to be let down by a low battery. Does anyone use a battery tender on their aircraft while they sit idle in the hangar? Just a thought.
 
Nite-owl

I have had battery woes similar to Mike's. The mechanic just overhauled the alternator and I am going to put a battery tender on at the mechanic's recommendation. I am curious to know if anyone knows of a downside to having the battery tender on the battery all the time while at rest.

Joe.
 
I have several of these battery tenders. I rotate them between cars, motorcycles and airplanes. They are inexpensive-about $7-$9. Seem to work for me.
 
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