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      03-20-2011, 06:09 PM   #1
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Battery Disconnect Q?

Perhaps a stupid question, but thought I should error on the side of caution. Rather be safe than sorry and all that.

When you disconnect the battery, does the car "forget" any of its settings? Or is it just a non-event? Does the length of time it is disconnected have any varying affect? And it's the negative side that should be disconnected, right?

Thanks for the help.
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      03-20-2011, 06:37 PM   #2
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I had my battery disconnected for ~5 hours yesterday while installing the BMW performance wheel. After putting it back in, the only thing that was reset appeared to be the clock. All my radio stations and bass/treble were still set the same.

Note I do not have iDrive, navi, etc. I have the basic M3 with only EDC. I'm not sure what crazy stuff the iDrive has since I never used it before.
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      03-20-2011, 08:59 PM   #3
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When disconnecting the battery I always disconnect the ground and tape it so that it doesn't have the chance to fall and re ground itself to the car messing up my computer and all that. Second the only thing that should reset is the date and time. No other settings should be reset such as seats, edc, radio stations, etc.

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      03-20-2011, 09:08 PM   #4
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Usually everything resets when disconnecting battery, so if it doesn't on this car, it'd be the exception. Based on Shamoo's input, the M3 is an exception to that rule . Good to know.

As a related comment, if you swap a charged battery for a new one with the same ratings (also charged), the car shouldn't need any 'coding' then, right? Or disconnecting the '+' as well erases everything? Curious.
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