I found this post somewhere and I have a similar problem. I have aftermarket speakers with an amp and a capacitor. For the most part my speakers haven't been working because my amp overheats and shuts off but 2 days ago I was using it and after I shut my car off and left it for about 20 min it would not start and battery was dead. I jumped it and everything was fine drove home about 20min drive then today battery was dead again. I had the same problem a few months ago where everytime I started my car the battery was dead but it hasn't happened in a while.

One thing I have noticed is the volt reading on my capacitor seems to sometimes stay on when my car is off could this be draining the battery? If not, is it a problem with my alternator?

 

How do you test your alternator? Can you keep the car running and take the negative off the battery? something like that to test the alternator. I think my alternators bad as well.

 

that is a test that was done years ago -
but i have read that it is not to be done now.
a surge may cause electrical problem
(just something i have read - anyone else heard of that).

 

sounds like an internal short that is draining the battery.
could be the alt (if it is that), or could be a host of other things.

take the ground off of your battery and hook up a VOM meter.
make sure to set it to dc amps.
attach the red lead to the battery cable and the
black lead to the neg battery post (i think it is that way - but if wrong then it will
kick the meter neg and then you will know that it is wrong, then change them around).

so, this is set up in series. Observe the amp reading.
you are looking for about 200 to 500 milliamps (just
to give you an idea of where to set the meter).
but i have to admit that i do not know very much about the aftermarket
music stuff, so i dont know how many milliamps that should draw (in fact,
i dont know if it draws or not). someone will have to answer that before i know how many milliamps the meter should show.
after that, i can tell you what to do next.

 

Tried a few more times to jumpstart my car but still no success battery keeps dying. I've disconected my aftermarket speakers so that no longer is an issue. While I was driving after I jumped it volatge continualy dropped below 12volts shutting off my cd player every once in a while but the car stayed on. I'm going to try buying a new battery and see if that works.

 

there is a electronic battery checker that is quite expensive.
auto parts store should have them and you should have the battery checked with one of those

 

It's pretty easy arithmetics. Your battery capacity is, say, 50 amps*hour. That means fully charged battery can provide you with one amp for 50 hours. Or 50 amps for 1 hour. If your dome light is 12 watts, it takes 1 amp at 12 volts. That means if you leave your dome light up for two days and do not drive your car during this time, your fully charged battery is dead. 500 milliamps drain, that fglaustin mentioned, will kill your battery in four days. If your battery is not fully charged, it happens much faster Any time you drain your battery completely, you reduce its capacity. Based on what you said, it is probably around 10-15 amps*hours now. And it takes much more than 15 minutes drive to charge it completely, even to this reduced capacity.
And, if you are able to run your car after you jump started it, your alternator is just fine.

 

http://www.hondaaccordforum.com/Batt...m_17476/tm.htm

this is how to test for a drain in the system

 

In your case just disconnect the battery once the car is started, your car only uses the battery for cranking over, after that its all Alternator. If the car dies with the battery disconnected you need a new alternator, if the battery wont hold a charge thena new battery might be a good investment also, it is possible for both to start failing at the same time. Also when Amplifiers over heat they can short, you might have over powered it and shorted the alternator and hopefully not the wiring system i.e. the regulator etc. Check regulator too, i suggest running higher Amp alternator like 160+ also to avoid this problem in the future.

 

read where that was not recommended anymore.
with the car running, connect voltmeter to the battery.
should read something like 12.8 to 13 (something).