I got up at 6:30 this morning and went to the store. No problems. I go out to leave again at 9:30 and my battery is dead. I can jump it and it will run, but as soon as I shut it off, the battery is dead again and it wont start. A couple times while driving, I hit the brakes and it would like die for a second and come back on, my cd player would turn off and back on real quick. Also a couple times when taking of, I had the RPMs really low and it did the same thing. Died for a second and came back on, and the engine did not shut off. I have a fairly new Optima battery, it should be good. Does this sound like anything else other than a bad alternator? Can it be tested while still in the vehicle, or do I have to pull it out and take it somewhere?

 

Its can be ur battery but i think its your alt, try to find sumone wit a vac 40 then test it out,for testing a alt u just need to put it on charge then hook up neg to neg and pos to pos then hook up the probe , then see how much your pushin. for a batery test u hook up neg to neg pos to pos hook up prob then fine wut is the Cold craking amp on your battery then divide that in half then adjust the vac 40 to the number

 

you answered your own question, alternator. its working just enough to keep the car running (once you get it running). but not working enough to charge your battery when driving. time for a new one.