So I have had My stereo system since july and my car was fine. I had a new deep cycle battery installed too. My car was fine until a couple weeks ago my car wouldn't start. Battery was dead , so I got another fully charged deep cycle battery, no luck turned out to be the alternator. My car has a drained battery the next morning. Something is drawing quite a bit of power so overnight it drains the batt. I just recently had a new cd player installed and this started happening short after, could they have installed something wrong?? My stereo is the only thing that draws power from my batt....no aftermarket lights ,,etc.
any help is appreciated

 

either that or there is a nice short somewhere, check all grounds, power wires, remote turn on leads etc. there is a short somewhere

 

It could also be a loose connection at the main fuse block (the one near the battery). When I replaced the battery cables in my FC, I hadn't tightened down the bolt on the fuse block that connects the positive lead wire from the battery to a ring terminal. I didn't end up with a dead battery though, but I noticed that my volt meter was reading about 12 V.

It could also be a drain somewhere. Maybe an amplifier or other component was wired wrong.

 

There are some ways to test the "draw" on the electrical system when the key is off doors closed etc. Normally you would use an digital volt ohm meeter. You would turn everything off and then select the highest amp setting. Disconnect ether the positive or negative cable and connect the amp meeter in between the battery terminal and the cable (neg or pos). You normally should not see over 1/2 amp or 500 milliamp. To give you a gage/ a single interior light dome/ will draw about 1 amp. I would look first at any bulbs with switches like the trunk light, glove box light etc. I also Will say a deep cycle battery is not designed to be placed in a car that's driven often. It's designed for things like a boat or R/V which sits around most of the time. The deep cycle doesn't sulfate like normal battery will if they aren't used. If you think something is causing the problem like the CD player I would disconnect the unit, remove the fuse along with the long term memory power. There is much more to diagnosing this but this is a start. Remember the basic charging system alt. battery supporting wiring also should be looked at. Most alternators running voltage is around 13 to 14 volts so it should be somewhere in between this at the battery when the engine is running and everything extra is off. The amperage out put of the alternator should be within 15% of it's stated output so it should put out over 80 amps. etc.

 

if ya dont find the prob......install a battery switch.... or take out the stereo and figure out where things went south....