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Key fob battery charging?

Discussion in 'DIY (Do-It-Yourself)' started by pyao88, Jul 15, 2011.

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    For key fob w/o comfort access is the key battery being charged when you plug into the car?

    Has anyone ever need to replace the battery if it's being driven daily?

    If the keyfob battery dies, and you open the car w/the metal key, can you still start the car by plugging in the keyfob?

    What about the key for Comfort Access, is there a way to charge they key's battery?

    Similiarly if the Comfort Access key's battery dies is there a way to start the car?
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    it's a regular battery. open

    it's a regular battery. open the key and replace it.
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    I'm with you - I thought that inserting the fob into the ignition would charge the battery, but it does not.

    The dealer just replaced the battery in my 2008 550i ignition fob yesterday.

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    Modern key fob batteries

    I was just in the dealership yesterday, so here is what I've learned:

    Modern key fob batteries charge by induction when they are inserted into the receptacle. However, as with other chargeable batteries, they will die over time. Expected life according to my BMW parts counter guy is about 4 or 5 years. Older key fobs used to allow replacing the battery. It depends upon the model/year. However, the new ones (like my 2007 328i key) require you pay for a new key.

    Comfort access keys have an additional battery in them, that also charges by induction. If these key fobs go bad, you not only pay more for a key, but you also pay for dealership-required programming. Again, my dealership says it is around 250 for this. I was told that you need to put it into the receptacle periodically to charge the comfort access battery too. [NOTE: according to the manual, it is not clear that this is a rechargeable battery, I'm just going by what the parts counter guy said]

    For either key fob, if they lose the battery, you can still unlock and drive your car. You have to use the little key that slides out of the fob to open the door, and you just stick the fob into the key slot and start the car. [Note: this is more information from my dealership, and I have not had this happen]

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