1999 Dodge Grand Caravan. Returned from trip to Maine, next day battery dead. Charged but wouldn’t hold so purchased new. Drove around that day, parked and next morning battery dead. Charged battery & alternator seems to be charging (12v off, ~14v while car running). Removed neg. bat. terminal and connected a test light light between the post and the removed clamp. Lights on power draw (open door), off otherwise. Cheap-o multi-meter set at 250mA pegs. Yanked every relay and fuse I could find (main box under hood, and another under dash (both on drivers side), everytime the meter still pegs. What else is there that is not fused/relayed which can draw power with the car off? Next step?
You have to connect the meter, and wait ten to thirty minutes for the current drain to settle down. (Some of the electronics in the car wait this long before going to “sleep”.)
Another test you can try is to measure the AC voltage across the battery when the engine is running. It should be well under one volt.
This article may give you some useful ideas: http://www.aa1car.com/library/battery_runs_down.htm
Don’t open the door after it has settled down. That can wake stuff up.
Dedicated ammeters can be had pretty inexpensively.
One item that usually is not protected by a removeable fuse is the alternator. So disconnect the alternator B+ lead headed to the battery and see if the current drain ceases.