Comment by sitkack

1 year ago

Many car's control units continue to run while the car is off. If you want to reboot your vehicle, you need to unplug the 12v battery for at least a minute.

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sitkack

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jcgrillo  1 year ago

On some cars (recent VWs in particular) when you plug the battery back in you need to twiddle some settings in the computer otherwise the charging circuit will fry the battery prematurely. We've gotten ahead of our skis with this nonsense, time to rein it in.

  • symisc_devel  1 year ago

    This issue is notorious for BMW cars. You have to notify the ECU each time you install a new battery.

    • jcgrillo  1 year ago

      It's hard to imagine an interpretation of this behavior that doesn't involve manufacturers trying to punish independent mechanics and end users who service their own cars. Like, there's no way it's an "honest mistake", right?

      BTW I have an AGM ("advanced glass mat") battery in my 1995 Toyota which has a completely analog charging system, and it doesn't get cooked, so it's not because there's something special about the battery.

      7 replies →

    • chiph  1 year ago

      That's because BMW ECUs adapt to the lower voltage as the battery ages and instruct the alternator/charger to provide more current. Replace the battery and the ECU would cause it to be overcharged unless you notify it of the replacement. Yes it's an over-engineered system, but ... German car.

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