Weird Electrical Problem, so frustrating... Options

[tonytutino]

All of this started when i got my amp/sub put in last month on the 19th. (Its a 800w amp powering a JL 12inch W3) Well, a couple weeks ago i noticed my battery didn't want to seem to hold a charge and eventually it just quit. So i bought a Duralast Gold battery from Autozone on the 16th of December (having them test my alternator too which worked fine) and it worked great up until today. It just was dead when i tried to start it. Didn't leave any doors open, lights on, etc. so i took it back thinking it was just a bad battery, well they replaced it and tested my alternator again and everything checks out... As soon as i got the new battery i drove 15 minutes to work and that was it. i come out 8 hours later and its dead AGAIN!
I have no clue whats wrong... even if the alt. was bad, i don't see how driving just a few minutes on a battery would drain it... anyone know whats up?

[woosey]

OK first off to check for a voltage leak somewhere you need a clamp meter that can measure DC voltage you turn your car off, make sure everything is off (interior light etc) and then test the battery + for current, you should only see around 0.3 amps being drawn when the car is off (the car alarm/immobliser using most of that!)

So common problems that cause battery drain are -

Poor alternator performance
Alarm broken/open circuit
open circuit else where on the car.

What i would do is -

1) Get your car started (jump start/bump start!)
2) Test your voltage with engine on, you should see around 13.6 volts on idle
3) Hold the engine at around 2k rpm, then test the voltage again, it should be nearer 14.2-14.4, if it is not, then your alternator is toast im afraid (its important you check the alternator does increase in voltage as engine speed increases, most people don't do this!)
4) If this does all check out then get back to me on what alarm you have and any other modifications you have done to your electrical system (added LEDs/sat nav etc)

I have a similar problem... I have an amp and volt meter and it seems like there are no major draws on the system.. seems to be fine if I drive it day after day.. but just got back from week trip and it was dead..

the amp cuts off cuz I have a switch to it plus it goes off when radio is off.. so IDK

I have a Optima Yellow Top Battery..

Can you test your DC current pull when the car is off/doors closed etc please? And we can go from there

This post has been edited by woosey: Jan 2, 2008 - 5:58 AM