Thanks for your replies. I have not yet been able to check w/ the volt meter but I went out to the car today and did the cluster voltage test and it showed 11.4V with lights off.
Started the car and it went up to 13.5, then turned it off after about 2 minutes and dropped down to 12.7 and within a minute it was back down to 11.5V. I went out to my E38 and did the same test on it and found the resting voltage to be 12.1V, started it and went to 13.6v and then turned off and it dropped to 12.7 like the X5, held my high beams on for about a minute and the voltage slowly dropped to 12.4 and settled out at 11.8V while still holding the lights on. I let go of the high beams and it jumped back up to 12.1V. Both cars are pretty much identical in terms of engine, alternator and in this case both have interstate 850cca batteries. The only difference would be the 7 series was driven today and the X5 was not, but up until yesterday, the X5 was a daily driver of approx 30+ miles a day. I don't think one day of not driving it would justify the voltage dropping down to low to mid 11's but then again I'm not an expert. I'm thinking of just ordering a Bosch battery this time around. Any thoughts??

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Say what you will, nothing drives like a BMW.


2003 X5 E53 4.4
2001 740iL Sport
1990 325i E30 - Restored/Restoring