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BMW Battery – AVG or lead calcium; good to know

Written by maryp posted on Friday, August 28th, 2009

3.00 avg. rating (72% score) - 1 vote

The modern luxury car such as a BMW, is using a considerable amount of electrical current even when you are not driving. The need for environmental, safety, ABS, electric power steering, DSC, your NAV, (this is not the complete list of features). Then throw in a few creature comforts, and the electrical draw is pretty substantial. You can count on about 100 or so actuator motors that need electrical current, too.

In the later part of 2002, BMW, started using a type of battery commonly referred to as a “glass-mat” battery or AGM, (absorbent glass mat), in a few of the models. This battery is very different than the lead-calcium batteries.

They usually have a much longer life and reliability, but yes, they are more expensive. They do a great job with your BMW that has a high current requirement upon start up. They are completely sealed and also equipped with a pressure relief valve. (You may also see the acronym VRLA, which means valve regulated lead acid). They vary completely in their charging process and let’s not bore you with those details.

But, one very different feature is that the sulfuric acid in the battery is not liquid in the housing. The acid is bound in the glass fiber separators. This lessens the chance of acid escaping and causing any environmental problems if the battery becomes damaged from a collision for example.

This is only a partial description of the benefits and features of an AGM battery. You’ll want to get your BMW battery replaced when necessary, by a qualified tech who know exactly what is specific for your BMW. They will also know how to handle it properly, safely and recycle the old battery as is required by law.

It is very important to note; Either you have an AVG battery under your seat or the lead calcium type under your hood. They are not interchangeable and you must not put an AVG battery in the engine compartment!

True story; At least 15 or 16 years ago, there was a customer who was pretty sure that we had spilled battery acid on the roof of her BMW. The roof! (We were sure that we had NOT been playing catch with a lead battery over the top of her car). As we all looked at it together, then touched the “sticky” stuff, everyone including our customer realized that it was tree sap. Much less of a problem than battery acid, and she promised to watch where she was parking her beautiful BMW.

Happy Motoring!

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3.00 avg. rating (72% score) - 1 vote

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