So yesterday I started my 79 camaro and everything was fine. When I turned it off the generator like came on and remained on when the ignition was off. It started right back up and ran fine, but I couldnt get the light off. When I went to start it today to check it, it was completely dead. I jumped it off another car and was able to get it to start. I disconnected thenegative battery terminal while it was running and the car continued to run.I hooked a volt meter up to the battery and got 12 volts while sitting, then the voltage dropped when I turned on the accessories. When I turned the car off I watched the voltage drop and die on the meter. Can my battery just not hold a charge?? thanks

 

my guess is that it is the battery that is bad. If you disconnected the battery and the car stayed running then the alternator is good. If your altenator is really shot then your car would only drive until the battery is dead. With your lights, a/c, radio etc... running it till it stalls shouldn't take long, you probally would have noticed about 10 minutes into your drive.

Take the battery to auto zone, pepboys, etc... they can test it for you for free. They can also test the altenator.

 

Well Ill just pull the alternator and battery and take them both up to auto zone tomorrow and see how they test...Thanks for the input...

 

If you had only 12 volts while the car was running your charging system is bad. A fully charged battery will measure 13 to 13.6 volts not running.When you start a non-computer car it is normal to seeup to 16 volts. Witheverything turned on you should not fall back to originalnon-stated battery voltage (13-13.6) If it does then your car is drawing more then thealt can output. Since you where running and had voltage drop you where running off the little charge you got from jumping the car.

If I had to guess the internal regulator shorted out and that caused charge liteand the battery to drain completely dead.If the battery has any age to itthis type of complete drain can push it over the edge.

 

That explanation seems to fit what happened pretty well...the battery is years old...its just the one that was in the car when I bought it...

 

Turned out the alternator was shot and it had killed the battery...after a new battery and alternator,it runs and starts better than ever...wprks for me