[QUOTE=rh71;836319]my SA says these batteries are supposed to last 7 years. Maybe he's talking about normal driving with a lot of highway...

They used to......not so sure about more recent batteries in BMW's with i-drive and automated this and taht.

My 1998 M3 (almost 14yrs old) is on it's second OEM BMW battery. However, it gets driven about 1,000-1,500 miles a year and sits with a trickle charger the rest of the time.

7 years is extraordinary for a modern BMW. The bell curve suggests 4-5 years, with the newer, electronic-intensive ones falling shorter.

Like I said, 7,5 years for the one in my X3 is phenomenal considering the temperature extremes and option-heavy vehicle (electric everything, heated everything). Then again, the X3 sees mostly highway driving, and I usually don't use the climate control unless needed.

ugh battery checked out ok and there are no codes which would show up if related to the charging system. And there would also be a battery warning light.

guess i'm gonna try the fuel injector cleaner... always thought that stuff was a gimmick... but I'm desperate now. If anyone has any other ideas I could throw at them, pls let me know.

Well unless you have a favorite, BMW has their own branded fuel injector cleaner.

Also, FYI the aftermarket diagnostic software from Autoenginuity will register batteries after replacement.:thumbup:

you can not start your engine?
something wrong with the system?

BMW branded fuel injection cleaner is a rebranded Chevron Techron concentrate fuel system cleaner. It's probably much cheaper to buy one at a local Chevron. And it's among the highest regarded cleaners in a sea of fuel injection cleaners.

Do you have a reference to show they are the same product?

Anyone got a gas chromatograph in their garage?

:)

Look at the bottom of the bottle; it might even say manufactured by Chevron in fine print somewhere on the BMW bottle (I don't remember; I haven't bought it in ages)

Correct.

Much easier than using the tomatograph.

http://www.xoutpost.com/bmw-sav-foru...r-techron.html

http://www.xoutpost.com/attachments/...bmwtechron.jpg
http://www.xoutpost.com/attachments/...ron-bottom.jpg