So last weekend my car would not start! It sounded like just a dead battery so I went and bought an optima red top battery and put it on. The car ended up working for about 2 days then died on my again. So I was thinking alternator...right? Ended up replacing the alternator last night and now it is still doing the same thing. Not Starting!!! Now when I was putting the new battery on the - and the + posts on the battery are backwards from the stock one, so with out even paying attention I put the cables on backwards!(I know stupid me...) Now all that had happend is it blew a couple of small fuses and turned my head lights on. I replaced the fuses but I ended up having to get some side posts for the battery because the stock cables wouldn't reach. So thats pretty much it...I've replaced my battery, alternator and have triple checked all the connections and everything looks fine! But still the battery is not holding a charge. I have no idea what could be causing this to happen! Any idea guys?

 

First I would try doing a voltage drop on the charging cable from the alternator to the battery. If your dropping more than 500 mv, or .5v. I'd say replace the cable. Also you may want to look and see if your alternator has a good ground. Check ground from alternator case to the negative post of the battery, see how much resistance you have. Also, I don't know the wiring of the vehicle too well, and I imagine that the alternator voltage regulator is internal of the alternator, but in case, check that as well. Let me know what you come up with.

 

Man I still can't figure this out! Went and had the alternator tested again and it passes but the bench test unit can only test the alternator at one set rpm. This problem only occurs at idel on my car....anything above 2500rpm's it puts 12v on the battery where it should be putting 14v. I'm starting to think there might be a fried wire somewhere and I'm going to be working on it all night. I was also talking to a friend of mine and they said its possible there could be a relay that could be fried. Any Idea's guys?