I've got a 97 850 with 105,000 mi. It's the base model with manual trans & no turbo. If the car is not driven for 2 days when the temp drops to the low 20s, the battery will go dead and I mean dead, less than 5 volts at the terminals. I've replaced the battery & used an amp meter on the battey cable to check for drain, nothing shows up. The radio was replaced with an upgrade & no change. The charging system checks out OK. It only seems to happen in cold weather. Warmer weather & the car can sit for 2 weeks with no problems. I'm assuming it must be a module in the electrical system somewhere that has a problem with the cold. Does anyone have any ideas or similar experience? Except for this it's a great car.

Charlie