Charging system wiring [Archive] - Forum


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01-21-2010, 04:39 PM
i have a 2002 grand am 3.4L

alright, over the past few months ive noticed that if i leave my car in the on position for more then 5 mins the battery is dead. now Ive tested the stock alternator, and auto-zone said it was good, i even took it off the car and they tested it and said it was good. when they tested the battery it said bad battery but that night i went home and charged it over night with the home charger, the next day i wen and got it check again and it tested good.

so i know the alternators good and the battery is good too. my suspect is that there must be something wrong with the wiring that connect from the alternator post to the battery. Ive heard some people use a direct line of 4ga works, but im afraid i will mess something up or screw up the computer. also i heard it might be a "fusible link" issue.

Any ideas are appreciated.

K WeRd
01-21-2010, 04:57 PM
Or it's just a bad battery....Get a new one.

01-21-2010, 05:06 PM
the battery is a gold series from sears and is under a year old

isn't it possible it got a false "bad" because it had almost no energy stored in it?

01-21-2010, 05:57 PM
Your battery is bad. Remember the battery have Volts and AMPS... maybe your volts are charged but the AMPS are to low.

Cold weather also affects the battery. I just replaced my yellow optimia and because the same problem. I don't use the car that much so the battery was lossing charged. So I purchase a nuew red optima and a battery maintener to keep the batter charged when I'm not using the car.

01-21-2010, 06:03 PM
Each time a battery is depleted and recharged it looses about ~10% of its capacity. If you have to charge it often then each time its loosing some of its holding power.

01-21-2010, 06:57 PM
Even if the battery is only a year old, it can still be bad. As stated, it losses capacity every time it is fully discharged. If you let it go totally dead too many times, it will be junk.

Also, just because you had the alternator out and tested doesn't mean it's good either. I was having charging problems and took out my alt and took it to advance auto parts and they tested it good too... even though it ended up having a bad voltage regulator. It couldn't adjust voltage and keep up with demand when any accessories were running.

You need to hook a voltage gauge up to the car (a multi-meter will work too, just hook it to any positive power source and ground the negative), and with the engine running start turning on accessories and see what happens. Turn on radio, A/C, headlights, etc... every time you turn something on the voltage should dip a bit then come back up. It shouldn't go under 12.5-13 volts if everything is good. If it gets down in the 10-11 volt range, your alt is bad.

You can upgrade the wire from the alt to the battery and it won't hurt anything at all. It's the same way the stock wiring works, you are just adding another wire for less resistance. Unless you are running a big stereo or a lot of electrical accessories though, it isn't necessary and you probably won't see any difference.

01-22-2010, 04:24 AM
Thank everyone!

i do have a 1000W hifonics amp running off the battery and some small acc.

i might add another wire for less resistance tho. one question about that though, when i add a new wire should i hook up the stock one too that also goes to the battery? or should i unhook the current alternator wire and tape it off and run only my new one.


01-22-2010, 06:49 AM
You can run both.