this is what i went with,
$195.00

Auto Zone 319458 H-7-AGM duralast Platinum

*** 850 Cold cranking amps (1000 cranking amps)***. 140 / 80 reserve minutes. Warranty consists of 3 years free replacement.Amp-hour: 80
Application: Automobile
BCI Cold Cranking Amps (CCA): 800
BCI Cold Cranking Amps Value: Tested to BCI Standard
BCI Designation: 94R
Battery Height: 190 mm - 7 1/2 in
Battery Length: 315 mm - 12 7/16 in
Battery Width: 175 mm - 6 7/8 in
Core Charge Applicable: Yes
Cranking Amps (CA): 920

This is the battery I put in my 2005 X5 4.4i. Only been in about 2 years now, but no issues so far!

Deka 9agm49 battery

Clockwork, can you clarify what you mean by "few tall wedges"? Are you referring to the battery hold down clamp that consists of a metal piece & long bolt where the metal piece is placed over the foot/base of the battery then the long bolt is used to secure the set up by screwing the bolt thru the metal hold down clamp down into the one of the threaded holes in the bottom of battery compartment.

If this is what you meant, then I'm further confused by the implication that you have multiple hold down clamps. You only need one which is usually located on the negative battery terminal side due to the vent tube being on the other side.

I'm just sort of confused not knowing if you meant the hold down clamp...or some molded in wedges in your battery compartment that I'm not familiar with . :)

#1 is the battery hold down clamp. ..is this the wedges you're referring to?. If yes, you should only need one:

Shouldn't the vent tube be connected to the drain tube on lead acid batteries?

Yes,

But the photo I posed above is for my 1998 Volvo S70: for that model, the battery is in the engine compartment.

For the BMW X5, yes, connect to drain tube.

I highly recommend Exide for the low cost of $94. I am staying away from Autozone Duralast battery.

Qsilver7, i will go take some pics now. As i am putting my new bmw h8 batt in now anyhow :)
So once i remove the metal 10mm nut and metal triangular tab which holds the batt down there are also 2 pillar like structures molded into the batt tubs base (showing in red circles in pics a few posts down from this). These triangular pillars are in lower right corner and stop an h9 batt from fitting
Also on the left side of the batt tub there are 4 or 5 plastic hold down fingers too that stop an h9 from insertion (showing in the red rectangle in the pic a few posts below this one).

Note the pics showing the physical dimensions of the tub on my 4.4i. Maybe the 4.8iS has a larger tub?

Thanks...my curiosity is piqued because the 4.8is isn't listed with the other models when pulling up the diagram for the battery compartment.

here are the pics
I also have pics showing the dimensions of the batt tub.
39cm L x 17.5cm W x 18.5cm H
(these dimensions are MAX and based on the fact that you have to cut down the peaks/triangles in the bottom right corner to achieve the length of 39cm).

Wow...thanks for the pics and education. The dimensions you give and show definitely are not within the specs of a 95R/H9 battery. I will have to add a note to my mental rolodex that the battery class best suited for the e53 is the 49/H8 dueto the tight quarters of the e53's battery box (aka multifunctional pan, trunk).

You can see what the length of the 95R (East Penn/DEKA) batteries are in the chart below...for those not familiar with centimeter/millimeters...394mm = 39.4 cm :D

http://www.bimmerboard.com/members/q...0H9%20Info.jpg

How are AGMs in extreme cold? Are they better or worse than regular batteries?