[revolverdyret]

My car won't start when its -25C or less outside, so I figure it's because my battery is six years old. I'm going to order a new one but I don't know what type I need. Is there anywhere I can check? Do i have to look on the battery itself or the manual?

When I look on site that sells oem bmw batteries I enter my license number there batteries come up:
70 AH AGM
90 AGM
80 AH AGM
80 AH
90 AH
70AH

The car is a 2006 e91 320i.

[robthewrench]

Look at your battery in the trunk to determine the size and type. Or go to mechanic who will do this for you if you ask them to quote replacing the battery.

You need to determine if the battery is conventional lead acid plate, or lead acid AGM. A white battery is a conventional lead acid plate battery, black is AGM. At least here in the U.S.A. those are the colors of those batteries.

You should replace it with the same type, unless you have a really good reason not to do so. If you do change types, you'll need to re-code your car to alter the charging cycle.

After determining the type, you can select the size (70, 80, 90 Amp hour). Again, replacing with the same size as the current is probably the easiest. The more AH capacity the higher the cost and the larger the battery. All of these sizes will typically fit in the e90 battery compartment though. Since you live in a very cold climate, I would recommend the 80 or 90 AH battery. This will typically be size factor H8.

You should consider registering the new battery with a programming tool or mechanic after installation as it will help prolong the life of the new battery. Look in the DIY section for more info.

[Wolfgang Schneiderhan]

Originally Posted by robthewrench

Look at your battery in the truck to determine the size and type. Or go to mechanic who will do this for you if you ask them to quote replacing the battery.

You need to determine if the battery is conventional lead acid plate, or lead acid AGM. A white battery is a conventional lead acid plate battery, black is AGM. At least here in the U.S.A. those are the colors of those batteries.

You should replace it with the same type, unless you have a really good reason not to do so. If you do change types, you'll need to re-code your car to alter the charging cycle.

After determining the type, you can select the size (70, 80, 90 Amp hour). Again, replacing with the same size as the current is probably the easiest. The more AH capacity the higher the cost and the larger the battery. All of these sizes will typically fit in the e90 battery compartment though. Since you live in a very cold climate, I would recommend the 80 or 90 AH battery. This will typically be size factor H8.

You should consider registering the new battery with a programming tool or mechanic after installation as it will help prolong the life of the new battery. Look in the DIY section for more info.

Good advice Rob. Get another battery of the same specifications (AH, CCA) and have it registered.