510 520 basically identical.

If you have mystery battery death check the starter current.

If you have a peak reading DMM you can measure voltage from cig lighter to the B+ jump point during a start. It shut be about 0.75V if the engine is warm but not started in the last few minutes. A restart should be about 0,65V.

Multiply by 280 to get an estimate of amps.

While stopped the voltage typically recovers. It's exactly while coming to a stop when the voltage Usually dips. Also that's when the trifecta will come on. So basically you need to be monitoring for a voltage dip right when the trifecta kicks in. That will indicate with certainty charging circuity problem.

Random ghost abs defeat that can't be traced, usually is the abs module. Often temperature related. If your abs works most starts then defeats regularly wheel sensor then abs module likely culprits

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)