There will be some diffference in the reading by a volt or two. I would not worry abouyt it.
you need to do a amperage test. Volts will not mean much.
Here is how you can test the alternator to see if it is bad:
Thanks for reading. I just replaced a battery in one of my vehicles that was reading 10.3v.
I installed a fresh new battery yesterday. And replaced the terminals with new ones. When running it was at 14.5v at idle, I can t recall if I had everything running though.
Today when I go out. The battery voltage reads 12.6. When I start the car, run the radio, 2 amplifiers, the lights and the heater full blast the voltage is 13.5v.
However, when I turned everything off the voltage remained the same. I mean would it stay the same? Would the car actually have to be producing rpm's for the voltage to increase? I hope I'm making sense.
Thanks for offering your insights.
