Battery Charging - Problem?

[SharpAndCunning]

Yesterday I was recalibrating the rain speed sensors and a battery warning on saying the car was going to shut off soon due to low battery.

I was vacuuming out the car today and when I was done I figured I would throw it on the charger for a little while, I only drive the car once a week or sometimes once every two weeks, and with the lights being on for cleaning and recallibration It seemed like a good idea.


After a couple of minutes I heard a buzzing and walked over to the charger (was on trickle mode) and the wire were warm. Much warmer than I would have expected. YES, I was charging from the terminal under the hood and the ground. I put the same charger on my motorcycle, let it run a cycle, not warm.

What is it with the Bimmer? Can you really only use a trickle charger on a bimmer? It is a AGM factory battery, and yes the charger was on AGM mode.