My E92 went into full on freak out mode while I was driving home from work - the warning lights on the panel took turns cycling through, the A/C and radio stopped working, and the windows were inoperable which was super given that I was sitting in rush hour traffic during the hottest part of the day in a black car.
A bit of Google-fu led me to the probability of a bad battery with many similar stories on the Internet. I called the dealer the next morning to price out the OEM battery. Hmm. That's way too much and that price did not include the battery registration required in order to allow the PCM to set the appropriate charging voltages and track battery life.
Once again, Google-fu turned up alternatives to the dealer and a bit of poking around led me to Bavarian Auto Repair with their array of 5-Star reviews. I was familiar with one of the other listed indy shops, through prior experience, and I wouldn't allow them to work on a dead cat that I found alongside the road.
A quick call to Bavarian Auto Repair and I had a lower cost than the dealer quoted for battery for not only a new battery, but the installation and registration. Sign me up! I arrived just as the battery hit the shop and hung out in the very comfortable customer lounge drinking coffee and reading current magazines. Whoa!
In short order the battery was swapped and the tech was checking voltages as the car idled. I wandered out to talk to him and found out that the voltage at the battery was running at about 17 volts. That's out of range for battery charging so it was determined that the alternator was also bad...which had probably gone bad and caused the battery to fail due to overcharging in a cascade failure mode. Cause and effect is always in play.
Discussion and a quote for the alternator R&R came and went and I left the car for the balance of the day. I returned just after 5:00 PM. The tech was just wrapping up the test drive of the car and making a few final checks, including resetting the date and time. The bill was paid. The car was back to acting as expected and I was happy with the service, the cost and the general tone of the entire process.
These are good people. They do high quality work at reasonable cost, they know BMW's inside and out, and deliver what they say they will deliver. I'd been looking for a new shop for my BMW and for my wife's Porsche. I am no longer looking.
Thanks! You guys rock!