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      10-02-2012, 10:27 AM   #7
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Drives: E92
Join Date: May 2012
Location: Charlotte NC

iTrader: (9)

Originally Posted by AW08M3 View Post
Had this issue also, dealership told me it was due to the fact that the alternator doesn't kick in for 15-20 min so if your daily drive is under that then battery doesn't get a chance to charge. Installed the trickle charger and plug it in once a week to top off. Time will tell I guess!
Thats a bunch of smoke. The alternator charges as long as the engine is running (variable no doubt but if it is spinning it is putting out current). Hook a volt meter up to the front jump posts, as soon as the car is started it puts out over 14 volts.
It may take 15-20 minutes to replace the charge that was taken out of the battery from starting the car and powering everything up. If it is only driven for 10 minutes I can see a cumulative draw.
Electronics Junkie, Engine Builder.