[align=left]Hi Everyone! So, I have a 1980 300d with a greasecar kit in it. The car has been stone reliable for the last couple years. It has a new (3 month) battery and a new (1 month) alternator. It's been raining quite a bit here in oakland and lately I've been coming out in the morning to find my battery drained almost completely dead. The car seems to be charging fine and it only seems to be draining on nights when it rains. I figured it must have something to do with the moisture shorting something and draining the battery. How do I track this draw on the battery down? Are there any likely places I should look? What is the procedure for diagnosing? Thanks, everyone. I really need to get this car going again.

take care
duncan
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there must be a large load to totally drain the battery over night. you will need your trusty multimeter on the ammeter setting. you need to establish a base line for current consumption on a none rainy/low humidity day. remove the ground cable from the battery and put the ammeter in series, with one meter lead on the +positive and the other on the -negative. you should get a small reading about 1/2 an amp. this current flow is normal as the electronics such as the radio need power to continue storing your presets.

now repeat the process on a rainy/damp night. your current consumption should be markedly higher most likely beyond the ability of your multi meter. this is ok all were are trying to do is establish that their is a higher current drain in damp conditions rather than in the dry.

if the current flow is higher in the damp you do have a shorting problem somewhere.

you will need to systematically remove relays from under the dash to find the offending circuit. on you have the circuit pinpointed you can try and substitute a new relay. if that does not correct the problem is in between the battery the ignition or the ignition and the relay.