2001 Mercedes Benz C320 Battery

2001 MERCEDES BENZ C320
140,000 MILES • 6 CYL • 2WD • AUTOMATIC
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STEVE FOSTER
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My mechanic tells me the alternator is overcharging the battery with over 14 volts, causing the battery to go dead overnight.

Is the alternator the real problem or is something draining the battery?
Jun 15, 2009 at 1:40 PM
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RASMATAZ
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If its over 15.5 volts its ovecharging the battery and can explode.
Jun 15, 2009 at 2:40 PM
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STEVE FOSTER
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Thanks Rasmataz, I saw the mechanic test the battery with the engine running and it was about 14.3 volts. He said the "overcharging" was causing the battery to go dead overnight. I think there is some kind of drain on the battery.
Jun 16, 2009 at 1:23 AM
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RASMATAZ
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To prove there's a battery drain do below


https://www.2carpros.com/forum/automotive_pictures/12900_parastic_draw_1_103.jpg

Jun 16, 2009 at 3:24 AM
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STEVE FOSTER
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Thanks again, Mr Rasmataz. My mechanic finally figured out the drain on the battery. It was the seat control unit...a very expensive part at $480...and they don't make any aftermarket parts like this one so the dealer was the only option. Appreciate the help!!!
Jun 21, 2009 at 1:29 PM