Originally Posted by claykin
My wife's '08 328 with 34K miles has begun slow cranking. Batt measures 12.2V at rest and 10.1V while cranking. I compared to my 2010 335 and I can tell her battery is on its way out. Took it to dealer and they tell me it passes BMW's battery test. They cannot replace under warranty. Argh!!! I suppose BMW wants customers to wait until its so dead it won't crank the car over. Lovely!
It's just a lead acid battery so other than the fact that it costs over $300 to replace at the dealership, I'm beginning to realize that we've made such a big deal about nothing (can you imagine people on a Sonata or Accord forum acting like this over a battery? Of course not, they run over to Sears and get the top of the line for $129 and just put it in and it's done for 4 years). The SA from before XMAS told me BMW rarely (read it as never but this forum says otherwise) replaces a battery under warranty, it's designed to go 5-6 years.
My car has been sitting since the Thu. before the XMAS holiday, no battery tender. Let's see how it does to work today. It's about 30F, not too bad, we'll see.