What is draining my car battery!! **Please Help**

[JettaBoy]

I bought a 2002 Jetta VR6, about a two months ago and a few weeks ago it started having battery problems, now when I first tired to start my car and it wouldn't I immediately went to AutoZone and got them to check my Battery and Alternator and both tests came back perfect nothing was wrong with any of them.

So I take it back home and the next morning I try to start it up and it doesn't. So I sent it to the volkswagon dealership and they thought it might be the battery isn't the right size or alternator so they installed 2 bigger and brand new ones. And then they send it back to me, guess what ? 2 days later I still can't start,

So then I send it back again and now he says that it might be my amp in back. I've been reading some threads about this, saying that maybe my amp isn't shutting off when I turn off the car, any idea on how to fix this problem with either my Amp or the car in general ?

Things you might need to know.

1.) I bought this car used

2.) The previous owner had a aftermarket Radio installed but I don't know how much he spent on it or even how to check what it is, but the dealership says the amp is stock.

3.) New Battery

4.) New Alternator

5.) The place I bought the car won't do support for it anymore and do not have money to have people look at it right now.



Thanks a lot for any help guys,

[aardvarkash10]

first, find a new company to service your car...

This isn't brain surgery. Put an ammeter into the main battery circuit and see whats happening. If you have more than (around) 0.25A current draw when the ignition is off nd not in ACC position, you have a problem

Disconnect stuff (or switch it off) until the current craw drops to zero, or near zero.

Congratulations - you've found your problem.

Any service company who replaces the alternator an the battery on the assumption that "they aren't big enough" are idiots. Tell them so.

The only thing more foolish is accepting that this is ok - go tell them to make it right, cos they HAVEN'T fixed the problem and thats what you paid for...

[Perry Babin]

Charge the battery.

With the headlights on, measure the DC voltage directly on the terminals of the battery.

Start the car and measure the voltage directly on the battery terminals again.

Let the voltage stabilize for a 10-15 seconds for each reading.

Post the voltage you read with the engine on and off.

[wrenchone]

Monitor the battery current as mentioned and see if there is excessive battery drain. If the current looks excessive, go to the car's fuse block/s (there may be more than one - check the manual), and start pulling fuses until the excessive drain goes away. That will at least localize the problem. I had a problem with the turn signal stem on my PT Cruiser that would cause the fog lights to turn on randomly and drain the battery if I didn't catch it in time. Sooner or later, I'll need to replace the turn signal stem that contains the switch for the fog lamps, but I'm a lazy git, so I pulled the fuse for the fog lamps (usually don't need 'em) and have had no problems since.

[pheonix358]

I once had a leakey diode that allowed battery power to leak backwards. It would flatten the battery over night. Easy to fix - hard to find in the first place. Found it by checking the drain as I removed fuses. With all fuses out the drain was still present. After that it was not hard to find!

Terry

[Andrew Eckhardt]

>the volkswagon dealership and they thought it might be the battery isn't the >right size or alternator so they installed 2 bigger and brand new ones


Whatever you do, don't go back to that shop unless its to collect money. Putting an ammeter in series with the battery and then pulling fuses one by one is a good starting point. One time I got booby trapped like this by a new used car. It turned out the brake light switch adjustment had moved so that when the moon was right it would never shut off even if I got out of the car.

[Mooly]

Something weirds going on... a new battery, let's say 60ah capacity and you leave it overnight and it doesn't start... that's some leakage current to do that, even drawing 2 to 3 amps for 12 hours or so and it should still start.
An old battery is a different matter and even a few 100 milliamps draw can see one off to the point of not starting... but your's isn't.
Can you feel this amp warm when it's off because that sort of power drain will cause heating.
I would disconnect this amp if you are not sure how to measure the current to it and see what happens.
Have you confirmed the alternator and battery really are new.
Be very carefull measuring current directly from the battery, it's easy to zap a DVM if for example the central locking activates etc as the current draw is huge.
Any luggage lights ? dicky switch.

[Andrew Eckhardt]

O geez I didn't even read that you have a custom audio system. Absolutely, for starters, isolate the audio system. The dealership should have at Least been able to tell you that's where the problem is, if it is, and ask you to take it to a place that deals with that stuff.

If you have no test equipment, take the power down from the audio system when you leave the car overnight. You can remove fuses from amp supply lines if you want to just troubleshoot that first, or you can come back and check for heat as Mooly suggested.

[ppia600]

1-Close all of the doors on your car except the trunk, leave it open
2-Disable/disconnect the trunk light (if it has one) and make sure all dome lights are off
3-Disconnect the battery ground cable and connect an amp meter between the battery ground wire and terminal. Make sure your amp meter is set on the 10 amp setting with the +/red lead in the 10 amp high current test hole
4-Watch current draw, it should stabilize to .05 amperes or less within two or three minutes
5-If current draw stays above that, pull the fuse from your car amp in the trunk. Now go back and check the amp meter to see if it drops to a normal level.

The guy who installed the previous system could have connected the trigger lead incorrectly to a speaker wire behind the deck or a constant. The amp could also have a defective internal circuit causing it to stay on.

[JettaBoy]

Ok so the amp is the problem that is draining the battery, so it is a stock amp. Do any of you know where the amp might be located at? And how do I disconnect it ?

Again it's a 2002 Jetta