My car keeps dying with a new battery - could it be the alternator?

I have a 2004 Pontiac Grand Am with about 130k miles on it. For some reason my car has been dying lately. It did this a few times so the obvious thing was to buy a new battery- oct 2011. Everything was good for a couple months but I recently went on a trip for the weekend and when I came home the car was dead. I jumped it and everything was good until this week. I had a work conference and left wednesday at 8am. When I got home Friday at 5pm the car was dead again. I had an alternator test done before but could it be the alternator? I love my little car and would like to get a couple more years out of her!!!

I assume that by “dying,” you mean you are getting no crank when you turn the key. Or will it shut down when you are driving too?

You should have your alternator and that battery checked. (New ones can have defects). Someone should also check your main power cables and their connections. But mostly someone should check it for parasitic drains - something sucking power that it shouldn’t be when the car is off.

If you drive mostly short trips in inclement weather, the short trips and the extra load of lights, fan, defroster, wipers, etc. can cause your battery slowly die, due to there not being enough time to put back what you’re taking out. The situation is worse with smaller cars, which typically have smaller batteries that don’t have as much capacity as the ones in land yachts.

If this describes you, try turning off all your accessories after you park, and just sitting there for a few extra minutes once in a while with the motor running, when you’re not in a hurry. Listen to the radio (which doesn’t use much juice) or just decompress from your day. This will help keep the battery charged.

But it would be good to have your alternator retested. It could be weak and not putting out as much as it should. Have the drive belt checked too to make sure it isn’t slipping under load. Cigroller’s advice is good. Make sure there isn’t some light staying on like the one in your glovebox or trunk, or a forgotten map light.

Sounds like there is a hidden load on the battery that is discharging it…A “Parasitic Load Test” will find out what it is. If you have a VOM, a multi-meter, you can do this yourself…

Thanks for the suggestions. I typically drive about 30-40min to work each day and live in NC so the weather isn’t bad. I do have subs hooked up which I had installed when i got the car. Could something with these have gone wrong? I will be sure to get the alternator, drive belt, and main power cables looked at. I’ll also have them do a parasitic load test.

Audio amplifiers can pull lots of power. See if yours is warm to the touch…

I agree…a parasitic drain, charging system or…poor battery should all be checked. Even if the battery is new, there is no guarantee it isn’t at fault, though I doubt it. Just drawing down a starter battery that isn’t deep cycle could weaken it. Have it all checked.

If you have an add-on amp and it’s mis-wired or failing, it may not be turning off when you turn the car off. When it isn’t being driven by the audio system, it doesn’t draw a ton of power, but could certainly run your battery down in a couple of days time. The parasitic load test should find it if this is what’s happening.