09 M3 Battery replacement (Duralast Battery)

[djt511]

Lately I have been getting the "Increased battery discharge" message at least once a month. I drive 20 miles to work and back (40 mile round trip) so there isn't a need to charge the battery every night, I figure my battery is dying. Car is an 09 so its lasted almost 6 years. Local BMW parts dept wanted $326 for a replacement battery (East Penn 90amp AGM battery) so the hunt began for a more cost effective option. Came across the AutoZone Duralast Platinum/Battery H8-AGM for $171.99

This battery is the same exact size as the current battery, with the terminals in the same exact position as the OEM battery. The ratings are almost identical as well. So if anyone is unsure what will fit in the battery compartment, this one is a winner!

OEM Battery Brand - Banner
OEM Battery SN - 61 21 7 575 327
900CCA 90AH
Reserve Capacity - 160

Replacement
AutoZone Duralast Platinum/Battery - H8-AGM
900CCA 92 or 95AH (Battery label says 95, AutoZone site says 92)
Reserve Capacity - 160

Now to get the battery registered

[JerryK73]

I just did this myself on Wednesday.

[BPMSport]

The Duralast battery is fine. I put one in my E60 550 and have had no issues. My 7 series also rocks one too, but that car is way before the days of battery registration.

[mxa121]

I plan on picking up one of these this week.

Out of curiosity, when I looked on OEM parts, it says the factory battery is 640cca and 80ah. I also have an 09 coupe.

Which is correct? The 900 like in your car or the 640 like the OEM parts site says? (My car also has a 640 installed)
I was under the impression that only convertibles got the 900.

Thanks!

[djt511]

Originally Posted by mxa121

I plan on picking up one of these this week.

Out of curiosity, when I looked on OEM parts, it says the factory battery is 640cca and 80ah. I also have an 09 coupe.

Which is correct? The 900 like in your car or the 640 like the OEM parts site says? (My car also has a 640 installed)
I was under the impression that only convertibles got the 900.

Thanks!

It depends on the options your car has, I called and gave BMW my vin and they gave me the part number to a more current (East Penn) 90AH Battery. So I know it's correct to my vehicle, and it would fit for you but it is a tight squeeze as the 90AH battery is slightly longer.