Wasn't sure where to post this, this seemed like the appropriate area. My battery recently went dead (turn out my alternator which decided to run its course. So I replaced the alternator, changed the battery, it went dead, so I changed back to my old battery (which I previously charged). It started up fine (this was yesterday) today I jumped in the car and it didn't start up as healthy as it normally would. Went to a friends, we had the doors open (interior light on) spraying some old crc in the joints, went to start her up and bang the battery's dead. It's really gotten to me know. My friends dad whom is a mechanic reckons my power wire to my amp is the problem, I can't see how so considering I've ran the same thing in my unregistered car that never left the back yard, if that's the problem how do I wire the damn thing up so it doesn't drain my battery, I'm not made of money and don't plan to buy a new battery every 2 days. He said to cut the wire and put some sort of switch in to toggle when the amp gets power, no idea how to do it or it could even be done. I just wanted people's thoughts/opinions. I don't really require the car this week, though I can't have this happening next week when I have school. Any help would be greatly appreciated, thanks.
Check the amp switch wire isnt connected to constant power. There is a wire from the amp that switched the amp on when the head unit switches on. If its constant the amp will constantly be drawing current, other wise it shouldnt be a problem.
Turn the cat off, head unit off, take the key out. Check to see if the amp has a light on it or not. If yes, you have a problem, if no, its most probably something else. Check the alternator again, just cause its replaced doesnt mean it works. Was the second battery new?
No it wasn't but it cranked straight away, I don't want to risk wasting money buying a new battery just yet if it's not the problem, is there a way for me to test the alternator?
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Originally Posted by havavb
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No it wasn't but it cranked straight away, I don't want to risk wasting money buying a new battery just yet if it's not the problem, is there a way for me to test the alternator?
You can test its output under load with a multimetre. It wouldn't hurt also to load test both batteries, as you said they weren't new, and they may be faulty.
Just run the car with a few things on (lights, stereo etc), bring the revs up off idle and check the voltage coming from the alternator.
Multi meter, it needs to charge at 13v I think, someone else smarter than me might be able to help out there. Start the car up and and check the voltage when its running, rev it up and see if it goes up, should be over 12v though for sure.
