The car is nearing 146,000 miles and with the exception of some nastiness around 77,000, has been going strong (thankfully). It's winter in Maine and I usually park her in the warm garage but with the salt mess on the roads now, I keep her outside. New Bosh S6 AGM two years ago (IBS knows) and no battery warning messages.

It was cold last night, around 18F, and around 33 when I pressed Start. The starter sounded weak and timed out after a few attempts. I pressed again and voila, she started right up but said that the passenger restraint system was nonfunctional. No battery warnings. The restraint message went away after the next restart (which was smooth). This has happened once a winter for three years. I never thought much of it but now that I'm committing to keeping this car past 200,000 miles, I want to make sure of any issues on the horizon.

Thoughts? I hesitate to think it's the battery because I don't see other signs and have no high-drain messages. Could it be the starter? Would there be other signs that I could look/listen for?

 

I would say it's the starter at first but when the passenger restraint is bad I'm leaning towards an electrical issue. First I would have the battery tested. I think that's what it is. If not move on from there.

 

The passenger restraint notification would lead me to check the battery.

 

I keep my car outside also in the Canadian winter. I found with the Pandemic restrictions and working from home that I wasn't driving as much, and started noticing slow cranks when starting at lower temperatures. I have a large AGM battery that I replaced 2 years ago, I just think that I haven't been driving the car enough to keep the battery topped up. I'm using my trickle charger now and everything is working normally. Maybe try keeping a trickle charger on it?

 

+1 The colder it is the more of the battery the car needs to crank. The OPs battery maybe fairly new but could need charging. In the winter time during real colds months I would keep a charger on the car. Especially if you're not driving it much everyday. These cars wake up and do checks all during the night draining the battery slowly but surely.

 

Thank you for your replies. Maybe this is finally the event that convinces me to buy a digital multi-meter. Good point about infrequent drives. I drive about twice a week and being out on a peninsula, the car covers at least 40 miles on each outing. I had been using a Noco Genius 7.2 amp charger frequently between drives but started to feel that it was overkill.

If the smart charger is to be believed, the battery is almost always around 75% regardless of a 4 hour drive or a 40 mile outing. I have been under the impression that its a function of BMW's rather odd charging methods despite this car not being part of the "efficient dynamics" program. I'm still in Bosch's 4 year warranty so I'll see if my shop will check it out.