Mysterious (multiple) battery drain?
 

Is this a thing?

My BMW has been giving me an error message which I find is relatively common based on message board search results. That error is "increased battery discharge." For the most part, it does not affect the driveability of the car, but it does prevent the smart key operation of unlocking the doors by touching the handle. I can still start the car with the key in my pocket.

That's not really the main subject of my question.

While this has been happening, I've also noticed:

• The batteries for my cordless power tools (two Craftsman C3 units) barely hold a charge. Once taken off their chargers and put in the tool, they only last for a couple of seconds.
• The LED indicator on my trickle charger for my Miata flashes rapidly rather than staying on solid. The car started today; I moved it a few feet, and then shut it off. I left it off the charger for about 30 minutes, came back out and it wouldn't start. Lights come on in the dash, but it won't turn over.

It's almost like the M3 is doing something that is draining all of the batteries in the garage (or preventing them from charging fully). Is that a thing?

I'm trying to figure out how two different battery chargers, plugged in to two separate outlets, and a car (not plugged in to anything at all) are all having their batteries slowly drained.

I will bring the power tool charger and battery in to the house and see if the battery will store and hold a full charge.

your car is an EMP.

Wireless discharging. Tesla would approve.

Obviously this is some form of German Magic. Your BMW doesnt happen to be an e30 does it? IRRC those were the last of the BMWs to come from the factory installed with German Magic. Otherwise this could be some aftermarket German Magic, and that could be the problem.

I hate you guys.

The BMW is the one in my signature; it's an E92. It has the "intelligent key" option. This includes the ability to lock or unlock the door just by touching the door handle and start the car with the push button (while the key fob is still in your pocket).

One of the other things the car does is it stays on for about 15 - 30 seconds after you turn off the ignition. That is, the stereo keeps playing, the windows can be rolled up and down, power seats moved, etc.


I have never heard of anything like this before, but it seems too improbable to be coincidence that all three battery-related items should start similar failure patterns at nearly the same time.

Sounds possibly drug related?

Aliens!

Or secret military technology!

My tolerance for this level of insubordination is quickly coming to an end.


I moved the power tools charger and battery in to the house earlier today. It charged up fully. There is a GFCI outlet in the garage so I reset that. If that's the issue, it would explain the battery chargers not working properly and would leave as coincidence the car battery drain.

It's possible that's as simple as the battery needing replacement. I'll throw the multimeter on it later.