can I use 100ah vs 90ah rated battery
 

Sorry fellas and girls if any out there, I well confused, on the realoem site it states my 30.d needs a 90ah

So for the x5 3.0d 2005 the battery i need the equivalent of the below:

a) Original BMW battery, filled 90ah part number 61218381768 or
b) Original BMW AGM-battery 90ah part number 61216924023


Okay i call the local distributor of bosch and he says my vehicle takes the 100ah and will be fine, he also says he supplies bmw dealerships on the island too...fair enough, issue is I have read that sticking in a higher rated battery can lead to electrical gremlins....yet according to another post here bosch suggest the 100ah battery ? confused or what:dunno:

Just called the dealer and he has 90ah listed for use in the 3.0d and nearly twice the price of the bosch

batterys are tricky. because bmw changed the ah a few times.
your best option is replacing it with the same ah that you currently have.
Dont forget if your vehicle does not have a voltage regulator. you will also need to register the battery with the car otherwise you will be going through a lot more than batteries.

X5_Meister has some good info here
 

As previously mentioned...you want to look for a 49/H8 or 95/H9 battery class size. These batteries will have the capability to be vented and have the specs required to operate our vehicles...as well as fit regarding length & height.

If the battery you purchase happens to vent from the top center...make sure that they give you a vent kit that will extend over to the vehicles vent tube which expels gases that naturally occur inside the battery to be vented to the exterior of the vehicle (unless your battery is mounted in the engine bay instead of being enclosed inside the spare wheel cavity). :)

Again, shop for a 49, H8, 95, or H9 battery class size. Battery class size is universal...so no matter where you live on the globe, any battery vendor can deduce what you are looking for regardless of brand name or battery manufacturer. :)

Qsilver7 thanks again so will the Again, 49, H8, 95, or H9 battery class sizes all equate to 90ah rated batteries, or going back to my original query can i get the 100ah and use it, and the registering the battery? totally confused now.

Can you use a 100 AH battery? Well, AH (amp hours) is just a way to rate a battery's maximum amperage that can be drawn until the battery is completely dead over a specific amount of time.

That means the difference between a 90 AH & 100 AH battery (all things being equal) is that under the same circumstances, the 1st battery will die a bit quicker than the 2nd.

Again, amp hours is only a rating given by a battery manufacturer that describes a battery's capacity of how long it will run before it is drained down. I have no explanation as to what you read as to why a 100 AH battery would be bad for your e53 versus a 90 AH battery. Perhaps they have a different understanding of AH (amp hours). :dunno:

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

No, just make sure that you protect the battery cables from contacting each other or other metal objects while swapping out the batteries. If you have some old rags (or old socks)...you can wrap or slip them around the ends of the pos/neg cables until you are ready to install the new battery.

Remove the negative battery cable first, then the positive cable...then reverse it when installing the new battery...go positive first, then negative. Try not to fiddle-fart when putting the negative cable back onto the new battery's neg post...you may get a spark or two...but don't let that frighten you and let go...just get that sucker on the post and any sparking will stop. Some owner not aware that it may spark slightly, may let go of the cable which may cause more sparking than if they had followed through with the original attempt. :)

100 Ah? No problem at all! By doing this, your battery may stay a bit longer in winter.