i was wondering if it is possible for the alternator to randomly not work and then work again. this is what ive done to test it:

-tested the battery while off, ~12.6 volts
-turned the car on for a few min. and then off, ~12.1 and steadily increases to ~12.6
-turn car on and tested batt., ~12.1 constant; then it all of a sudden jumps to ~14.3 volts
-try the same test a few times and it will sometimes just stay at ~12 volts forever, sometimes jump to ~14 volts, and sometimes start off at ~14 volts and stay there.
-whenever it stays at ~12 volts while running and i turn off the car, the voltage will steadily increase to ~12.6 volts, or when its at ~14 running then off, it will go back down to ~12.6.
-today after a 15 min. drive with radio on, i came home and tested the battery before turning the car off and it was fluctuating around ~11.8 volts. and when i turned it off, it went up to ~12.6 again.

i just want to be sure that its my alternator so any help and input would be greatly appreciated. sorry if any of this is confusing, id be happy to clarify. thanks a lot.

 

ok i just drove the car around and at the lights, the batt. light would come on and i have to rev it a little. well i got home and checked the batt. and it was reading 10.3 volts while running and when i turn on cd player and headlights, it goes to 8.something.

i think everyone is pretty sure that its the alternator, but could someone tell me why or how the voltage jumps from 8 to 11.something right when i turn off the car and why it continues to increase to 12.6. that would be very helpful. thanks

 

Did you ever figure out the problem, because i am having the exact sam symptoms. Sometimes the voltage is fine and other times it is down around 11 volts. I guess it is just the alternator, but i was wondering if you figured out your problem.