Went through similar problem with my dad's car recently. I pulled apart the fuse block and internally it had 4 canon plugs. Pulling one group at a time eliminated 10-12 fuses at a time and tracked down the drain quickly. In his case was "operator error" he left his mirror mounted map lights on for 2.5a drain and his car doesn't time out.

42w drain is enough to make whatever part of the car physically warmer than a the rest. Put a charger on to keep the bat from draining and scan the car after sitting overnight and scan the car with an IR thermometer. Something should be 5-10°F over ambient. You have to catch before the sun hits the car (in a garage best: Wind will also foil the experiment).

The other test method is to run through ammeter and turn every device on/off and when you engage something and don't get an appropriate change in current that's the culprit. Example. Each window draws 1.5A except one that draws 0.5a. Means the window has a short pulling 1A idle.

Did you have any coding done? A bug in coding could leave some accessory always on. Have a 3rd party power sub or amp? Broken relay could easily be the culprit they usually are hard wired to the battery with their own fuse.


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2011 E70 • N55 (me)
2012 E70 • N63 (wife)