How can I tell if it is my battery or my alternator

Asked by Jul 11, 2014 at 09:00 PM

Question type: Maintenance & Repair

My car can be jumped
off  but if you leave it
setting without applying
gas it will die and not
start back until you
charge battery a little or
jump it off but battery
won't hold charge

1 Answer


Easy, do you have a volt or multimeter? Engine off the battery should be 12.3V or higher. Engine on, 14V. If you readings are lower, then you know what is suspect. A local auto parts store will also inspect/check/test your battery and alternator for free. How old is your battery? More than 5 years old? Time for a new one.

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