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BMW Battery Change Select Smarter

Written by maryp posted on Friday, March 23rd, 2012

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If you think you can save some money buying a less expensive lead acid battery instead of the more expensive AGM type in your later model BMW, it is not a good idea. The battery “registration” is a programming function that lets all of the control modules know that you have just installed a new battery. If you originally have the AGM battery and you put in a lead acid battery, the car will need extra programming besides the “registration.” That is because it is not originally programmed to recognize the lead acid type battery. Now, you have not only spent more on the programming, but the lead acid battery is just not going to last as long. So, do not plan on saving any $$ by getting the cheaper battery. It is not going to be worth it in the long run.

Depending on your later year and model BMW, the BMW Intelligent Alternator Control, aka IAC, places battery monitoring and charging on the DME, (Digital Motor Electronics). Due to the increased number of convenience and comfort items and features, your battery is being subject to heavy use while you are just enjoying the gadgets. What this means for you as a driver is that your glass mat battery (AGM type) is being charged as you accelerate, cruise or idle, any time the state of the charge is below 80%.

In the professional shop setting, the chargers for the AGM batteries are much different than chargers for lead acid batteries. That is why you want to be using a technician or shop that has the specific equipment. In your modern BMW, MINI or Mercedes, the specs for almost everything on these cars has become very, very unique and tolerances tighter. It can be “sticker shock” the first time you have to replace of these AGM batteries, but that’s technology for you. Note: Don’t try to use your old battery charger on your AGM battery. If it is still a good battery, it can be damaged.

Your new gadgets and creature comforts in your later model BMW are resource hogs for sure. Don’t let an alternator or battery problem grow into something worse. Always follow at minimum your BMW inspection and maintenance schedule. You will for sure want to go to a BMW specialist or a dealer who will have the proper equipment for your AGM battery.

Do not try this at home!

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