Very cold weather startup performance - battery life?

[Powerslide]

This will be the first winter where I will be driving my M3 as a daily driver (3.5 years old, 38k miles). I just recently had my car inspected at my dealer - original factory-installed battery reportedly still in good condition.

For those who have DD their M3's for several seasons now in severely cold weather (especially where parked outside all day while at work in sub-zero F temperatures) - I have two questions:

1) has the car always started up fine after sitting outside for about 12 hours in sub-zero fahrenheit temps?

2) has anyone had to replace their factory-installed battery yet (and if so, after how many years/miles)?

I think I'm probably fine for this winter with my factory-installed battery (build date June, 2008) - but a little reassurance (or a heads-up) from some cold-weather DD verterans would be greatly appreciated!

[pbonsalb]

I was just at a dealer open house and asked the service department this question. They say that the batteries should go 6 years on the cars that are driven and maybe 4 years or less on the ones that are parked most of the time and driven only short distances. I am in southern NH, which is not as cold as Chicago.

[Powerslide]

Originally Posted by pbonsalb

I was just at a dealer open house and asked the service department this question. They say that the batteries should go 6 years on the cars that are driven and maybe 4 years or less on the ones that are parked most of the time and driven only short distances. I am in southern NH, which is not as cold as Chicago.

Thanks - good to know!

[socalm3lover]

The battery on my July '08 build (65k miles), just died. I would at least have the dealer do a capacity test and would consider replacing it preemptively even if the battery tests good.

John

[Michaeljh2000]

I've had my 09 for two years as a DD. It's not as cold as Chicago here, but VA sees it share of single digit morning temperatures. I've never had any issues, its always started right up. The motor seems to run and shift (DCT) much smoother if I allow to idle for a few mins before driving away.