Need Help Analyzing Battery Issue

pinmagic · 11-25-2013, 07:45 AM

My 135i vert is just over 3 years old. A week ago, I got in the car after it had sat for several days, and I got a message on my nav screen to the effect of "excessive battery discharge," but my P3 gauge showed the battery voltage to be well over 14 volts. I drove the car a bit, and when I stopped, I sat in it with the radio on (no headlights) for about 3 minutes, when the same warning appeared. Again, the voltage was well over 14 volts. It's happened a couple of times since. No problems starting the car each time.

How can there be "excessive battery discharge" when the battery appears to be fully charged? Do I need a new battery? If so, any recommendations for a brand, or should I just go with BMW's battery?

Thanks!

Dackelone · 11-25-2013, 07:54 AM

Do you have 14 volts with the engine running or with the engine off? Normally a battery needs to have at least 12.8volts standing - measured across the battery terminals. And with the engine running it needs to be over 13.5volts. Time to whip out your VOM(volt ohm meter)....

pinmagic · 11-26-2013, 01:14 PM

Thanks. I'll check that.

11-25-2013, 07:45 AM	#1
pinmagic The Only Sane One Here 61 Rep 1,135 Posts Drives: 135i Convertible Join Date: Jun 2010 Location: Arlington, VA iTrader: (1)	Need Help Analyzing Battery Issue My 135i vert is just over 3 years old. A week ago, I got in the car after it had sat for several days, and I got a message on my nav screen to the effect of "excessive battery discharge," but my P3 gauge showed the battery voltage to be well over 14 volts. I drove the car a bit, and when I stopped, I sat in it with the radio on (no headlights) for about 3 minutes, when the same warning appeared. Again, the voltage was well over 14 volts. It's happened a couple of times since. No problems starting the car each time. How can there be "excessive battery discharge" when the battery appears to be fully charged? Do I need a new battery? If so, any recommendations for a brand, or should I just go with BMW's battery? Thanks! __________________ 2011 135i VERT SGM/SB/MOONLIGHT - ED - with every single friggin' option they offered.
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11-25-2013, 07:54 AM	#2
Dackelone European Editor 10539 Rep 22,992 Posts Drives: N54 e82 Join Date: Feb 2010 Location: Bayern, Germany iTrader: (1)	Do you have 14 volts with the engine running or with the engine off? Normally a battery needs to have at least 12.8volts standing - measured across the battery terminals. And with the engine running it needs to be over 13.5volts. Time to whip out your VOM(volt ohm meter).... __________________ Dackel's European Delivery Museum Guide
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11-26-2013, 01:14 PM	#3
pinmagic The Only Sane One Here 61 Rep 1,135 Posts Drives: 135i Convertible Join Date: Jun 2010 Location: Arlington, VA iTrader: (1)	Thanks. I'll check that. __________________ 2011 135i VERT SGM/SB/MOONLIGHT - ED - with every single friggin' option they offered. Last edited by pinmagic; 11-29-2013 at 07:42 AM..
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