[Shaun @ Tru6]

Nice day today so I thought I'd put fog lights back in the front bumper with new bulbs in the BMW. Found the connectors were heavily oxidized green, cleaned those submersed in water/baking soda. Turned the car on a few times to check the bulbs (one connector was wonky) and one time it wouldn't start but then it did. Turned car off (had been leaving it "on" to listen to the radio, and buttoned everything up. Went to turn car on and it was dead. 9V at the battery went to 5V even with a Gooloo tender/charger on it. Finally pulled that off, pulled battery terminals off and put the Noco Genius 5 on it.

Driving to work this morning no issues, no dash light. When doing the lights, started right up to change wheel direction for access.

How does a battery die in 2 hours? Bad part is windows are down, sunroof is open and super smart BMW engineers decided to lock the key in the ignition when battery dies. WTF.

It seems impossible that soaking the fog light bulb connectors in baking soda. Or leaving the key on listening to the radio 2-4 10 minute periods.

How do you think this happened?

Duragold is probably 4-5 years old, no date on top so who knows. 2007 328i.