Battery draining - Question with amp reading on voltmeter
 

I'm pretty sure I have a problem with something running my battery down. I do have a Pettit fan switch and the Mazda fan mod which keeps them running a bit after shutdown, however my battery is draining completely so I'm concerned. I checked the current draw between the neg. battery terminal and the - ground cable. This is a picture of what I got. Looks like 42 millamps to me which I think is a bit on the high side.

Can anybody confirm that I'm reading this correctly and that I have the proper setting on the meter itself? My apologies, I think I'm over thinking it but I just want to be sure.

My only modifications that use electricity are an AEM water injection kit and two Greddy electronic gauges. The gauges come to life with the key is turned, as does the AEM system. I installed them all according to the instructions. The AEM pump does have a wire going directly to the + battery terminal but is certainly not running all the time.

You should put your meter setting to DCA / 500m for current measuring, now you're measuring voltage.

Well thats a good start!

Alright, I got the meter in the correct setting and it keeps blowing the meters fuse which is 500ma. I guess I have at least a .5 amp draw. I'm sure it has something to do with the water injection system. I would not expect the gauges to draw much power and they are always off when the car is off. Maybe a portion of the water injection system is staying on.

I read that the glovebox light is usually a prime offender for drained batteries. The switch that turns the light off doesn't always depress all the way due to poor tolerances of the glove box.

Well now you basically have two options to measure what is draining your battery, if you want to use your current meter that has 0.5 amp limit, disconnect all fuses from your fusebox and one by one insert them back and see when you either get measurement or blow a fuse. Option two is what I would suggest, that you go and buy some cheap meter that has at least 10A limit, it would make things lot easier. Then you can just leave fuses in and take them out one by one and see when the current drops. If you can't drop the current to near zero by taking fuses out, probably some of your aftermarket parts are draining the battery by not going to stand by-mode.

disconnect the neg terminal from the battery
connect one end of the meter to the now open battery terminal
connect the other meter end to the neg cable you just removed
set meter to amps dc
see what the reading is with eveything off and the doors closed
even doing this the inital inrush current may blow the .5amp fuse in the meter