phantom battery drain

[conquesttsi]

Just got back to Connecticut from Ohio
Went to start the vr4. The battery is as dead as can be.

Any idea what might cause this phantom battery drain? Anything that is a common cause? Do I have to start chasing shorts with an ammeter?

 

[gvr4ever]

Maybe the battery just died. It happens.

 

[conquesttsi]

sorry I forgot to indicate this is a brand new battery and I drove the car the weekend before I left both Saturday and Sunday and the car was fine. I was only in Ohio for a week. I suspect a bad Alternator but could that cause a parasitic drain?

 

Most times it can be traced to a map light left on, door ajar, or something dumb like that. When it happened to me in #1886 one time I just connected an ammeter inline at the battery and started pulling fuses. It can also be caused by a bad diode in the alternator.

 

[conquesttsi]

I know for a fact there were no lights on or anything...I suspect it could be the diode though. Do you know how to test it to be sure rather than just throwing another alternator on? I also wondered if it might be a malfunction on the factory alarm unit, not sure if there is a way to disable it.

 

[grocery_getter]

Twice in a row I've found on customer car that their radio fuse is the culprit.

1. Use a multimeter, set it to measure amperage.
2. Disconnect the negative battery terminal from the negative battery post.
3. Put one probe on the negative terminal, put the other probe on the negative battery post.

Now everything that make an electrical loop back to the negative battery terminal will have to go thru the multimeter and you'll be able to measure the current.

4. With car off, key out, the amp value should be very very low in the .01A range, anything more than that then you have an electrical draw somewhere.
5. Start pulling fuse until you find the electrical branch responsible for your draw.


Don't forget that the modern day car alarm and other car electronic accesories sometimes is still connected to the battery even though it is not on and could be responsible for your slow electrical draw as well so if you already exhausted all the factory fuse points, start going after all the aftermarket electronic add ons.

 

[conquesttsi]

There are no aftermarket electronics in the car aside from DSM Link and gauges. I guess I better just start the standard testing with the ammeter..what a pita.