Charging system

Lately I have noticed my volt meter is only reading 12.5 volts. I think it should read 13.7, or close to that. I flew tonight before dark for about an hour and 1/2 hour in I turned my strobes and position lights on. After 5 min. the volt meter said 12 volts. I then turned my landing light on and it went down to 11.5 volts. If I turn everything off it will go up to 12.5 volts. One more thing, the battery is almost 5 years old. Could a faulty battery do this or is it the alternator? (0-320, 160hp)

Tim
2+2

Your charging system is not working. Assuming your alternator is externally regulated, check voltage at the field terminal on the alternator with the master and alternator turned on and the engine not running. If you have battery voltage (full field), your alternator needs work. If you don't have battery voltage, check wiring, if that's OK, than your regulator may be at fault.

My battery voltage show 14.6 with no elec load and 14.5 with a load and crusing rpm. Battery voltage is 12.4 or so when you just turn on the master switch. My regulater ( LR3 ) was preset at the factory for 14.6 volts.

Thanks for your help guys. I finaly got to the bottom of my alternator not chargeing. First the battery was 5 years old and wouldn't hold a charge. The main problem was the alt. belt, it was worn out and was sliping. I had to take the prop, and nose bowl off to get at things, so I took the alt. to a local shop to be checked. I put every thing back together and went flying, everything checked out ok. Thanks again

Tim
2+2