Hello - when I drive my car it seems to drain the car battery. For some reason it seems like it's running off the battery and not the alternator. I just put a new alternator and battery in. Ran a couple errands, came out of the last store car battery was 100% dead and couldn't hold a charge to be jumped. Got a new battery, had it installed and then disconnected it overnight in case there was a parasitic drain on it. The next morning I drove 3 short 30 min drives and the warning battery low light comes on when I get home. Additionally the car recently overheated because of a bad fan control module, I installed a new one and the part was defective. I have not yet removed the defective part because new one has not arrived yet. Is there any way a fan control module could do this? Or is it coincidence that the battery problems started right after I installed it. Also had the new alternator tested at O'Reilly autoparts and they said it was good.

Any suggestions, ideas, theories???

 

Sounds like you've already done some tests with your volt meter. Just to be sure, start your car up and measure across the battery posts to see if you are getting a solid 14V to the battery from your alternator, then clean and retighten the battery cables. As to the current drain, anything that has a motor can draw a lot of current,, ie an electric fan or fan clutch is probably up the top of the list. What I'd do next is start by popping out the fuse/relay to the fan and see if you can rent an ammeter to measure the current draw with the fuse/relay in or out.