Registering and Coding a new battery
Make sure you understand the difference between “registering” and “coding”.
Registering: doing this tells your ECU that you are replacing your OE battery with an equivalent. An equivalent is defined as same battery type (wet cell vs AGM type) and same Amp Hour rating.
The only two AGM batteries I have found to be form-fit-and-function compatible with the OE BMW battery for the ’08-’10 e70 is the Duralast H8-AGM and the Deka 9AGM49 (as a matter of fact, the Duralast is made by Deka for Autozone).
Register the new battery with the ECU requires that you know the Amps/Hours (AH) rating of your new battery. If you don't know the AH rating, you can calculate it based off of the Reserve Capacity rating, which is generally easier to come by (should be stamped on top of the battery).
Calculating AH rating based off of the Reserve Capacity rating:
Amp/Hours = (Reserve Capacity / 2) plus 16 (i.e. If your battery had a Reserve Capacity of 100, you would get 66 AH rating)
To register the battery you need to have a K+DCAN USB interface, INPA compatible cable and software.
Software for registering a new battery is available as a free download at
Bimmersoftware.com. This software
does not allow you to do any coding!
Coding: in the event that you get a battery with a different Ah rating, you will have to re-code the Amp Hour setting/rating in the ECU.
To do this, you need appropriate software to access the settings in your ECU. Unfortunately I do not know how to do this because I have not yet found the appropriate (and easy to use) free software. Dealers charge anywhere from $400 to $600 for this job, including a new battery.
If anyone knows where to get/download the coding software, please share!
Once you have the software, choose the AH ratings option closest to your battery. The available setting are outlined below. The first six are Wet Cell standard style of batteries and the others are the newer AGM style of battery.
KLASSE_BATTERIE:
46ah
55ah
70ah
80ah
90ah
110ah
40ah_agm
60ah_agm
70ah_agm
80ah_agm
90ah_agm
This will re-set the alternator to the correct Amp output for your new battery. If you do not do this, you will run the risk of either under-charging or over-charging your (new) battery. Either is undesirable and will lead to odd electrical behavior.