Testing for a current draw

[turbojimmy2]

A friend of mine has a '91 Chevy pickup with a 305. The battery goes completely dead after 3 days whether he drives it or not. Alternator is charging but not as much as I thought it should (about 13.6 volts when it's running). He just replaced the battery because of this problem and it's still doing it.

How do I test for a current draw with a DVOM. I set it to milliamps and checked across the battery. Is that right? I got nothing.

Thanks,
Jim

 

[TURBOV6]

Originally posted by turbojimmy2
I set it to milliamps and checked across the battery. /QUOTE]

Nope. You have to disconect the negative of the battery then measure across the ground to the battery terminal. But you will have to switch the lead of the meter. It might be a good idea to get a meter that will measure 10a max current, milliamps might not be enough and you might blow the fuse if you go over that.

 

[1ARUNEM]

Or use a test light and start pulling fuses (make sure the door is closed so the dome light isn't on) till the test light goes out.

Then you've found the culprit.
HTH..

 

[Marc87GN]

Originally posted by turbojimmy2
A friend of mine has a '91 Chevy pickup with a 305. The battery goes completely dead after 3 days whether he drives it or not. Alternator is charging but not as much as I thought it should (about 13.6 volts when it's running). He just replaced the battery because of this problem and it's still doing it.

How do I test for a current draw with a DVOM. I set it to milliamps and checked across the battery. Is that right? I got nothing.

Thanks,
Jim

I would have the alternator load tested. You either have to bring it to a shop or have a DVOM with an inductive pickup and test the alternator current output under load. Just because it puts out good voltage doesn't mean the AMP output is sufficient.

The draw test they are talking about is a parasitic amp draw which when you hook it up the way they describe(In series), it should be below .05 if I remember correctly or between .01-.04. If you have a draw that is killing a fully charged battery in 3 days, it's going to be much more than 1 amp.