can I use 100ah vs 90ah rated battery

[omodos]

Originally Posted by dkl

Agreed. You would definitely want to get the largest Reserved Charge (RC) and Cold Cranking Amp (CCA) that will fit. In this case, the 100AH battery would be the better battery given the aforementioned choices. I'm not sure why you want to go with a lesser specs battery.

BTW...there is no battery registration on our E53. Battery registration only applies to the newer models.

QSLIVER7 and dkl thanks, so no battery reg.needed great, and I got hold of the bosch pdf battery guide online (portion attached) and cross referenced it with the spec of my car I got from bmw direct (hence the german) according to bosch the 3.0d takes the s4 battery and they are 100ah, doesn't seem to be explicit mention of M57/TU engine in bosch list but my car falls in the production date they list (ps do i need to remove any fuses before swapping out battery?)

x5 info from bmw direct:

Produktionsdatum
13.11.2004

Modellzyklus
01.10.2003 bis 30.09.2006

Motor
M57/TU

BOSCH PDF BATT GUIDE