I have an '07 and have had the discharge warning about 6 times. I've started putting the car on a BMW battery charger about once a month. Typically, if a battery is normally charged, it'll go to a green light in about 10-20 mins. Each time I put it on the X5 it takes about 4-6 hours, charging the whole time. I drive about 30 miles each day, more than enough for a charge. I read somewhere that some newer BMW's were having this problem because of bad or undersized alternators. Anyone know about this?

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E70 X5 3.0si Space Grey

E36 Z3 2.5i Roadster, Sterling Gray Metallic