How to find an electrical drain

[k20]

Ok, so I have an electrical drain in K20. If it sits for more than a week the batteries (dual) are dead. I have unhooked the batts from each other and let it sit and only one goes down (the one hooked to the starter/factory wiring) and the other stays up. To rule out a bad battery I swapped their locations, and it still drew down the one hooked to the factory wiring (the other has the headlight relay harnesses, extra lights, electric compressors, etc hooked to it).

I read online and people were saying to hook a test light between the battery and the negative cable and pull fuses til the light goes off.....Well....if I hook in the test light, it doesnt light up! Also it doesnt register on my multimeter. WTF am I doing wrong?

 

[4X4HIGH]

You will use a DVOM (Digital Volt Ohm Meter) and set it to read milli amps and then disconnect the negative battery cable and place one lead of the DVOM on the battery post and the other on the negative battery cable and you should get a reading. Now start removing fuses until the meter reading changes and once it does you can now determine what items are on that particular fuse and start chasing the problem from there.

 

[Fordum]

There is something screwy here.
If you did what your post tells me you did, then you do not have a drain.

Since its obvious you do, someway we are on different tracks.

4X4HIGH is right, except in this case, you might want to start off in amps instead of milliamps.
A load big enough to drain two batteries in a week might blow a fuse in milliamps.

I'm sure you have already done all this, but lets go through it step by step, because something is missing.

First, disconnect both ground cables from both batteries.
Then, just in case, try hooking the test light from one negative battery terminal to the cable that came off it.

If no light, then leave that cable unhooked and try from the other negative battery terminal to the wire that came off it.

If the test light does not light up then, leave both negative wires off, and do the same thing as before except use the voltmeter in place of the test light, with it set on 12VDC.
Make sure its set on DC.

Double check the meter by going across the battery terminals to see if it shows 12volts.
After that, you should get a reading of 12 volts from one negative terminal to its cable on at least one battery, maybe on both batteries.

At this point, we know you are set up correctly to find the drain. Now, switch the meter to amps or miliamps and you should get a reading.
Make sure you are set on DC.

DO NOT try to test the meter by going across the battery terminals with it set on any kind of amps.

If you are lucky you will only blow the fuse in the meter. More than likely you will blow the meter.

If you did not get a reading of about 12 volts from either negative post to its cable, with both unhooked and the meter set on volts, then let us know. I have another couple of ideas.

Using volts instead of amps or milliamps, is a much more sensitive test, but its not any good for actually finding the short.

Like 4X4HIGH said, you need the amps reading for that.

J.

 

[xCaliK5x]

I cut one of my meter leads and put a blade fuse socket inline with a 7.5 amp fuse in it so it blows the cheap easy fuse before the 10amp inside my meter. If its a few weeks before it goes dead, its a small draw in mA. Like stated earlier, assuming its constant, put a meter inline and start pulling fuse's to isolate the circuit, then start unplugging components on your circuit until you find the consumer.