I am having a problem keeping my battery charged. Just bought a odyssey pc680 and installed it car was not started for three days, now dead. Anyway took multimeter checked battery while running showed 13.3. What voltage should the alternator show at idle and reving? Thanks for any help

 

14.5V

your alternator needs replacing, or there is something wrong with the system like a loose ground.

 

i agree i think the alteranor is fried