My 2007 M6 convertible is now off warranty/maintenance and the battery is going out. The BMW dealership wants to charge $410 for the part and (probably) an hour for install/charge.
The 5-year warranty Interstate battery for this costs $179 plus lower-priced installation ($20). BMW says that the battery needs to be registered with the computer - they will do it for $65 - but is this really necessary?
Any reason that's worth $250+ to get the BMW battery?
Your M6 most likely has an AGM battery, which will have a black case and no inspection "magic eye".
BMW NA uses replacement batteries manufactured by East Penn, part number 9AGM49. Auto Barn is one of several online sources.
Originally Posted by bernhtp
BMW says that the battery needs to be registered with the computer - they will do it for $65 - but is this really necessary?
I would register, since it is likely that non-registering will reduce the life of a new battery. On the other hand, some dealers charge so much to register, it's cheaper to just replace more often
$65 is not unreasonable...
Is there a material advantage to the AGM over the Interstate?
AGM is a more advanced battery design, for more demanding applications. The charging requirements are different, but the car can be coded to support AGM or conventional battery types. It is easier to just keep using the same type.
If you do have an AGM battery, your mechanic should be able to get the East Penn battery (which is available under several brand names).
That is a good price that Clyde found for you on the battery.
If there are some independent BMW repair shops in your area you might get it registered for less - it is reported to be as low as a $25 fee. Even if you buy a non-OEM battery you will want to register the new battery to the car. The BMW uses an Intelligent (I use that term loosely) charging system that adjusts the charge to match the battery as it degrades over time.
I do say, if it is so smart and can determine if your battery is getting weak and can adjust the charge, why can't it figure out the battery is stronger when you replace it??? Why, because they want to scam a register fee out of you.
The independent BMW repair shop only did Interstate - not AGM - but also didn't recommend Interstate for the M6. They gave me the same price on the BMW battery and $110 to install/register the AGM if I got it.
I just ordered the AGM and will install it myself. I might get it registered with BMW for $65 unless I find a better alternative. I imagine that registration requires special computer-connect equipment that only exists at shops that explicitly handle BMW?
What exactly is `battery registration`? and is it really necassary? What happens if it isnt done?
BMW has optimized charging to adjust as a battery ages, so a new battery is charged differently than a old battery.
How charging is "optimized" is not clear.
Battery registration informs the charging system that a new battery has been installed. The mileage of each battery registration is also stored.
Failing to register a new battery means it will be charged like an old battery. In theory this might reduce the life of the new battery, although there have been many posts about owners having no issues. Older M5/M6 models are now having their first battery replacement, so it is too soon to know if not registering will reduce the life of the replacement battery.
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