What is lost when you disconnect the battery?

Wolfus Aurelius · 07-19-2019, 01:35 PM

Last week, as you may have read, my F30 took on a little water in a heavy rainstorm, several inches in the passenger footwell. The car still started and drove fine, but the wipers and the front windows began to misbehave. To keep the other windows or sunroof from opening, I popped the cover in the trunk and disconnected the battery's negative cable. When the tow truck arrived the next day, I reconnected it. The car started and could be driven right up onto the flatbed.

What settings will I have lost with this emergency procedure? Different cars do it differently. I have not done any coding. I presume I'll have to re-enter my presets for radio stations and iDrive screens, my settings for the door locks and how the car behaves when you open it and lock it with the fob, etc. Anything else? Or is there something that you'd think would be wiped, but remains?

Most important: Will the car's memory for the last Auto-Stop-Start setting remain, or should I have the dealer re-code it?

Billfitz · 07-19-2019, 01:40 PM

You'll have to reset the clock. That's it.

Wolfus Aurelius · 07-19-2019, 01:45 PM

Quote:

Originally Posted by Billfitz

You'll have to reset the clock. That's it.

That's all? The car has an internal battery to supply power to other items when the main battery is disconnected? Good thinking on the Bavarians' part.

Billfitz · 07-19-2019, 03:34 PM

The memory is non-volatile, just like the memory in a laptop. You don't lose saved data on a laptop if you remove the battery, iDrive is the same. The clock doesn't use stored data, so it has to be reset, unless you have it on automatic tied into the GPS, in which case it will reset itself.

07-19-2019, 01:35 PM	#1
Wolfus Aurelius Lieutenant 133 Rep 433 Posts Drives: 2015 BMW 328i (gold/cream) Join Date: Mar 2019 Location: Da Swamp iTrader: (0)	What is lost when you disconnect the battery? Last week, as you may have read, my F30 took on a little water in a heavy rainstorm, several inches in the passenger footwell. The car still started and drove fine, but the wipers and the front windows began to misbehave. To keep the other windows or sunroof from opening, I popped the cover in the trunk and disconnected the battery's negative cable. When the tow truck arrived the next day, I reconnected it. The car started and could be driven right up onto the flatbed. What settings will I have lost with this emergency procedure? Different cars do it differently. I have not done any coding. I presume I'll have to re-enter my presets for radio stations and iDrive screens, my settings for the door locks and how the car behaves when you open it and lock it with the fob, etc. Anything else? Or is there something that you'd think would be wiped, but remains? Most important: Will the car's memory for the last Auto-Stop-Start setting remain, or should I have the dealer re-code it?
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07-19-2019, 01:40 PM	#2
Billfitz Lieutenant General 8239 Rep 16,075 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	You'll have to reset the clock. That's it.
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07-19-2019, 03:34 PM	#4
Billfitz Lieutenant General 8239 Rep 16,075 Posts Drives: '15 328iX GT Join Date: Jan 2015 Location: New Hampshire iTrader: (0)	The memory is non-volatile, just like the memory in a laptop. You don't lose saved data on a laptop if you remove the battery, iDrive is the same. The clock doesn't use stored data, so it has to be reset, unless you have it on automatic tied into the GPS, in which case it will reset itself.
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