Unofficialbmw.com

dale · Joined: 22 Aug 1999 Posts: 3087 Location: Seattle, WA USA

I was looking at batteries at Autozone the other day and noticed they now have a pretty complete set of AGM batteries in sizes that fit BMWs.
The Optima battery is cool, but it's not a good fit in an E30 without either a special mount or modifications to the factory mount.

The AGM batteries for BMWs are in BCI group sizes 47,48,49, check out some of the pictures in the link below and inline below.

Here is a new battery size that I haven't seen before, H6, H7, H8, H9
I believe they match the old BCI group style like this:
47=H5 ( early 4cyl E30s )
48=H6 ( 6cyl E30s )
94=H7 ( upgrade battery for 6cyl E30s )
49=H8
95=H9

My previous long post on batteries:
http://www.unofficialbmw.com/phpBB/viewtopic.php?t=30946

http://www.unofficialbmw.com/images/wheel_refinish/

More info on AGM batteries, which are starting to come from the factory in newer BMWs:

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sold in 2016
87 325 5spd eta

idanity · Joined: 21 May 2005 Posts: 3097 Location: N.W.U.S.A.

nice to know.

as my brand new walmart battery died in 5 months on the red sedan.

also, the AGM's are not for the cabrios...is a caseinpoint, my cabrio has also not liked the red-top optima gel battery. (died in 3 years, unlike my truck which has had the same optima gel battery for over 5 years now).
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Ken Juul · Posted: Tue Dec 13, 2011 12:52 pm Post subject: RE

Those are some expensive batteries!

5 months and 3 years is not normal life. Under or over charging is what usually kills batteries. Might want to get the charging systems checked before you install a new battery. The voltage regulator is usually the cause, last time I purchased one I think it was about $40, took 15 minutes to install, alternator does not need to be removed.

dale · Joined: 22 Aug 1999 Posts: 3087 Location: Seattle, WA USA

One point made in the article I linked in, is that AGM batteries should not be used in the engine compartment as the heat from the engine will shorten the batteries life.

Since the cabrio has the factory spot for the battery under the hood, I wonder how the AGM battery would do in the trunk on a cabrio?

Dale
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87 325 5spd eta

Bimmerboy1989 · Joined: 19 Aug 2003 Posts: 476 Location: Houston, Texas

I have a AGM from O'Reilly. Exactly the same as the Autozone ones because they are both made by East Penn Mfg. It is an excellent battery and has not died yet. I have a coupe and it is in the trunk.

Cephas · Joined: 02 Mar 2003 Posts: 767 Location: Chicago

I'm pretty sure this is what I currently have in my iS. I'll take a look when I get it back in the garage!
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-Peter-
My first - Sold:
1986 325 (5 Speed)
"The Dirty E30"

My Dream - Bought April 2012
1989 325iS 103K Miles
BBS RX
H&R Cup Kit
Original Schwarz