DEAD BATTERY OR ALTERNATOR

[fsbaksh82]

Hi
My battery died and car wouldnt start. I have a portable jump starter and that started the car . After I got home, about 10 minutes later, I tested the battery, car not running with a voltmeter and i got 12.2. Tried to start it and it would not start and the voltmeter read about 9. I jump started it again and the battery read 11.2 while the engine running. Is this enough to say the battery is not good? or is it the alternator not charging it properly? Thanks!!

[WDRacing]

Your best bet is to have the battery tested at any auto parts store, Autozone etc.

[Jesda]

Some Nissan alternators are unable to fully recharge a completely dead battery. You may need to put the battery on a charger overnight.

[MinisterofDOOM]

Voltage at the terminals with the car running should be over 14 volts. If it's not, I'd suspect the alternator. But it's worth getting the battery tested. Just don't count on parts-store alternator diagnoses...many times alternator problems are intermittent and fly under the radar of these kinds of testers.