Noticed you have a diesel and I also found where others were seeing 400 amp draws cranking the same diesel motor you have with the same battery run down problems trying to start them at times. No solutions posted though.

One thing that could account for the draw would be your glow plugs.

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Just BMW's - All cars and trucks was two pages long
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1997 528i
2000 323i
2001 X5 3.0 auto
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2011 535xi auto
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Aftermarket E53 Radio Install