Battery or alternator?

[sup2jzgte]

Ok I have 1999 Chevy Prism. Now today I went outside to start my car and it wont turn over at all. So I thought I had left something on and my battery died, so I had my neighbor give me a jump, but still it wouldnt turn over. Now Im not sure if I need a new battery or a alternator. I took my multimeter and tested the battery and it read 12.54 volts without the any accessories such as lights, radio, etc on. Then when I turned the lights on the multimeter read 11.26 volts. Im not sure if it a battery, alternator, or maybe even a starter, so does anyone have an idea?

[johnholl]

Originally Posted by sup2jzgte

Ok I have 1999 Chevy Prism. Now today I went outside to start my car and it wont turn over at all. So I thought I had left something on and my battery died, so I had my neighbor give me a jump, but still it wouldnt turn over. Now Im not sure if I need a new battery or a alternator. I took my multimeter and tested the battery and it read 12.54 volts without the any accessories such as lights, radio, etc on. Then when I turned the lights on the multimeter read 11.26 volts. Im not sure if it a battery, alternator, or maybe even a starter, so does anyone have an idea?

What does the bat voltage read while key is turnned to the start position? If it is still up there, you may need a starter.

Starters are one of the few problems with the Prizm

[highlandlake]

Originally Posted by sup2jzgte

Im not sure if it a battery, alternator, or maybe even a starter, so does anyone have an idea?

I'd agree with JH, suspect the starter as being the cuase.
Tom

[drhillier]

before you condemn anything what you need to do is trickle charge your battery for several hours. 12.5 volts is the bare minimum for a healthy battery so it's definitely low. once it is charged, disconnect your ignition system and hook the multimeter back up to the battery. have someone crank the engine over for 5 seconds and watch the meter. if it drops below 10.5 volts at any time, get a new battery. if the battery passes, hook your ignition back up, and start the car. check voltage at battery and verify that you have at least 13.5 volts. if not, it's your alternator, or something else wrong with your charging system. your starter will usually crank over slower and slower over a period of time before it craps out. not always, but usually. if you still have problems, you can remove the starter and take it to the auto parts store and get it bench tested usually for free. the battery goes dead overnight, you have what is known as a parasitic draw, and that is a whole nuther story. good luck.