Thread: Electrical Problem

after shopping for a new car this weekend, I decided to keep my trusty reliable b14 and just "refurbish" her. I just don't want any car payments right now.

anyway onto my problem.

there is something draining my battery when the car sits for a few days. I know there's a way to test for draw with a multimeter but I'm not sure if I am doing it right.

can anyone explain the process to me so that I can make sure I'm doing this right so I can pinpoint the source?

put the positive on your battery and the ground to ground....set to ma(milliamps)
watch the meter and have someone pull one fuse at a time until you see a change.
That will be where to start.
I am doing this now too.
If I drive the car daily it is fine,but if it sits for 3-4 days it will be dead as a doornail.
Jay

^^Agreed.. But, I normally start with all of the circuit fuses in the engine compartment next to the battery.
Doing this process, its a good time to install a fresh set of fuses in there. They can get weak and wear out too.

Then, I do the fuses under the dash.

Just to clarify, the above statement is a little confusing.

Disconnect the positive terminal on the battery. Put the positive lead of your meter on the positive post of the battery and the negative lead on the terminal. Put it on mA or what ever setting you have and start pulling fuses.

Obviously the domb light and other interior lights will have a draw. so pull the lights or turn them off. Other circuits like the radio will have a slight draw to keep memory but not a whole lot. You are concerned with anything that is sucking over 300ma or so, those will drain the battery.

Also go get your battery checked out, mine did the same thing but with a new battery it can sit for a week and have no issues.

What voltage is the battery when the car is running? Then right after shut down? Running with a bunch of ACC's on, like headlights, blower, AC, ect? Then after sitting for 4 hours or so? This might let us know if the battery is good or maybe the Alty is not charging properly.

yes, don't just hook the leads directly to the battery with it set on the amp scale, you will blow the fuse in the meter. The multimeter has to be set in series with the battery. Also, you have to have the meter on the right setting and the leads in the correct spots on the meter. Use the 10A settings so you don't blow fuses inside the meter.

If you don't know electrical very well you can always pull one fuse at a time until the problem goes away lol. Also make sure the alternator diode bridge is good, otherwise a blown diode can apply power to the rest of the electrical system through the fuse box. I don't wanna confuse anyone, but trust me. have the alternator checked to make sure the diodes are good. Autozone does it free and they can test it in the car. If they are good then go on the the next thing...the battery. Make sure that holds a 300amp load for at least 15 seconds without dropping below 10V. They can test that too.

Thanks for clearing all that up,guys .I was in a hurry posting,lol

I'm going to mess with this tomorrow. Thanks for the help.