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From digest.v7.n635 Fri Nov 21 21:47:05 1997
Date: Fri, 21 Nov 1997 17:56:50 -0500 (EST)
Subject: Beware the E36 M3 Battery!

The battery recently went out on my 1995 E36 M3 and this may apply to some of the other 3 series cars, but I'm not sure.. Fortunately, I was still covered under the SPECIAL battery warranty as spelled out in the warranty manual. You may not be so lucky, so I'll pass this information on.

While I was lucky enough to still be covered under the special battery warranty of 2 YEARS or 50,000 miles beginning at the vehicle IN-SERVICE date (which is not necessarily the date when you purchased it!). It so happened that the battery went out on Saturday, the dealership's service department isn't open, and I had an important event to got to on Sunday. No problem, I thought. It's only a battery, I'll just call the parts store and buy a cheap one to get me by so I can still take the M3 out for some Sunday fun. NOT!

It turns out that the E36 M3 battery is very unique item. It's a Group 92 vented battery made especially for BMW by a company called Douglas. If you want the proper battery that will mount in the factory hold down, you'll either have to get it from a BMW dealer or Douglas. You won't be able to simply match one up at Sears, GNB, Interstate, etc. The dealer list is approximately $125.

While this didn't prove to be why my battery failed, the BMW mechanic told me that the #1 cause of premature failure for this battery is the cells going dry. Since it's mounted in the trunk under the plastic tray, it becomes an "Out of sight, out of mind" scenario. The factory battery IS NOT maintenance-free and the owners manual states that the battery cell liquid level shoud be checked every 2 weeks. As with any maintainable battery, if the battery cells need water you must use purefied water, either distilled or deionized, as the minerals/chemicals in other types of water will ruin the battery's effectiveness.

Of course, unless you don't value your eyesight I wouldn't recommend peering into an open battery cell without some type of eye protection (That's acid in there, Bub). Also, unless you're at least as smart as the genius who used a Bic lighter to check the level of the 5 gallon gas tank in his garage (he's not with us any more and his family now lives in a cardboard box, Darwins Theory of Selectivity was well proven that day), I wouldn't recommend trying that either as battery acid fumes are also flammable. On the otherhand, standing at a 50 foot distance and watching an acid bomb go off in the back of your neighbor's pristine BMW could make for an interesting event on a dull, quiet suburb weekend. At least it's easy to dial 911.

FYI, a kitchen turkey baster works great for adding water to the battery cells without spilling or overfilling. As could be expected, cars operating in higher temperature climates are more susceptible to battery liquid evaporation and should check their battery cell levels regularly. At least now you'll know what to expect if your battery conks out. May the battery force be with you!

Mark Sipe

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