When I drove my IROC home after buying it a couple weeks ago, I noticed that it took a long time to get the volt meter back up to 12v after taking a few tries to start it in the cold weather with a defunct choke. Also, when I turned the blinkers on, the volt meter flicked in unison with the blinkers. Now I've got a very tame stereo wired up (Head Unit + 2 30W RMS 6.5" speakers) and if I turn the lights on while the head unit is on, the head unit cuts out and won't go back on until I turn off the lights (mind you I was running the engine at about 2k RPM and the battery had just been fully charged with a wall charger when this happened). I can't see any of these problems being caused by wiring... I completely forewent the car's stock wiring when I installed the stereo, so it should be completely seperate from the charging system, it has a hot lead for constant power on to the deck and then another wire with a switch in the middle to simulate the accessory position in the ignition circuit, the ground is good and the stereo wires are all new. I suppose the only other option is that the battery is just getting ready to give up the ghost, but I have left the car alone for about 4 days between times I've worked on it and it seems to hold a charge. That and the battery ran for 3 hours today at 12.0v playing music as I worked on the car before I put it on the charger.

I suppose I should take the alternator in for testing and if it's good I'll try replacing the battery. Any opinions?

 

I would get a volt meter and read the battery voltage (motor off), then start the car and read battery voltage, the voltage should be anywhere from 12.5 to 14, espically on a cold start. Alternator's are more efficient when cold. The Voltage should be a bit higher, if your battery was fully charged. If your getting 13-14 volts then I would check out the battery.

Good Luck