Quote:
Originally Posted by halfmoonclip
You're saying the battery does not get adequately charged under normal driving conditions? That sounds like something wrong, and you should be asking some questions.
Moon
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Yes, the AGM battery charges at almost 1 volt higher than a regular battery, but the X1 computer eats up that voltage checking itself when not used.
After reading about people having low battery light, and checking with voltmeter, I caught voltage around 12.1 or 12.3 many times before starting when it should be 12.5+.
As you might know the alternator charges as a braking feature when you let off gas. It doesn't charge while accelerating unless battery needs some.
With a scangauge on a long drive, I could see battery charging 14.6 volts for 500 miles, then going to second mode of 13.8, and finally 3rd mode of 12.6 (charged).
I can come home and drive 2 days later and it;s back to 14.6 volt charge, and I don't have electricity to charge where I park.
When dealer had it for cam check, they checked the 14.7 voltage and said normal.
One poor Scottish guy found this out with his X1 all decked out with heated stuff, and needed tow to dealer.
I heard battery can cost $700. , so don't let it run down ever, and the info will be in the computer saying you let it run down.
I leave for 3 months at a time so I took off neg cable and it started fine when I got back and reconnected.
If I could charge battery BEFORE road trip I imagine I'd get better mpg since the alternator would be not charging.