[isuzudave]

I am trying to figure out how old the battery in my 2008 328i is. There is nothing stamped on the battery terminals.

There is a heat stamp in the plastic near the positive terminal that says "AA27 K".

There is a sticker on right side that says "A4".

There are two circles with arrows pointing at numbers heat stamped on the bottom. One circle has numbers 1-12 and the arrow points to 6. The other circle goes from 13-20 and the arrow points to 13.

The only marking that seems like an obvious date are the circles that would indicate June 2013. But, they are on the bottom, and I think that might indicate the date of the plastic case, bot the battery.

The battery part number is 61 21 2 353 810. Anyone able to shed some light on this?

[gbalthrop]

Originally Posted by isuzudave

I am trying to figure out how old the battery in my 2008 328i is. There is a sticker on right side that says "A4". [Installed January, 2014 perhaps?]
There are two circles with arrows pointing at numbers heat stamped on the bottom. One circle has numbers 1-12 and the arrow points to 6. The other circle goes from 13-20 and the arrow points to 13. The only marking that seems like an obvious date are the circles that would indicate June 2013. But, they are on the bottom, and I think that might indicate the date of the plastic case, bot the battery.
The battery part number is 61 21 2 353 810...

Light:
1) That Part# is from 4/9/2013 per RealOEM.com, so newer than that:
https://www.realoem.com/bmw/enUS/par...1+21+2+353+810

2) Your theory about the arrows on bottom of case is probably correct;

3) Any sticker on the case is likely to be placed there by the selling Retailer, so SWAG: A4 = January 2014

4) INPA/ISTA provide for "Registering" the battery, which is a simple process in INPA of pressing "Batterietausch Registrieren" button/ Function Key which automatically enters then-existing odometer reading in km into your DME memory. It's NOT a date, but the mileage in km when that button was pushed. Your car doesn't know when/if the battery was actually changed at that mileage, it just copies km from odometer to DME memory when the button is pushed.

The latter is the way BMW techs know km at which "Last Battery Replacement" occurred. So if you had INPA/ISTA and knew what vehicle mileage was in January, 2014, you could check the SWAG.

George