Older Merc (06) and just dropped in a Walmart AGM - from memory (?) first replacement main battery after OEM, (they have two batteries). No registration or coding available. Battery life was fine until I sold it last year. Later model (2016) BMW requires new AGM (H8) battery registration when replacing, so the charging algorithm adjusts to a lower
rate for the new battery, and then builds over time. Smart charging system adjusts charging rate based on battery age and Ah
. Importantly coding (not registration) lets the controller know the capacity (Ah) of the battery.
Installed OEM battery is 92Ah, but most available H8/49 replacements are 95Ah. Not sure if the +3 Ah matters but requiring a new battery will be my catalyst to buy an OBD bi-directional scanner, needed even if one just registers. Most below $500 scanners only register, do NOT code
so not certain what to do without further research. Have also noticed on YouTube vids, that many OBD scanners may NOT provide a 92 AH setting, only 90 Ah or 95 Ah. Recommendation is to go to the next lowest setting - in my case 90 Ah, 2 Ahs below.
If I get the same (92 Ah) in the replacement, registration will be relatively easy with a more affordable bi-directional scanner with no need to code.
Oh the joys of owning a newer "hi-tech" car!!