Having trouble keeping battery charged on my 2006 Z4, had it to dealership twice who say nothing wrong, just don't drive it enough. It's my daily driver, office to home and back, about 5 miles perday in city traffic. Any ideas? None of my other cars (2009 Mercedes ML350 & Chrysler Van) have this trouble.
How old is the battery? Is it the original one? Why not have a load test done on the battery, just to rule out a possibly bad one? Many auto supplies will do them as a free service... I have a battery tender-type charger on my 07 Z4 coupe, but it isn't a daily driver by any stretch of the imagination. Still, it has the original battery... No issues... Yet.
Pyewacket1 is right on the right track with the issue. If your only driving you car 5 miles a day you should by a smart trickle charger for your vehicle and hook it up twice a week at over night helps a lot with maintaining the battery and makes it last twice as long. Also most lead acid batteries start failing after about 5 years so check your date on the negative post. If you want you could check to see if your car has a draw on its battery. Message me if you want specs and the procedure on how to. Hope this helps and good luck.
You want the Battery Tender with the accessory cord (or you can make one easily enough) that will plug into the cigarette lighter; since that's constantly "hot" in the 2006 Z4, it's a two-second operation to hook it up. Today's BMWs have mysterious power requirements. If I let the roadster sit for more than a week, it will indicate its unhappiness by a weak starter: rrr....rrr....rrr. That's my cue to go drive the hell out of it or put it on teh Battery Tender.
