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      07-01-2012, 07:57 PM   #27
John 070
Lieutenant General

Drives: 335i cpe
Join Date: Oct 2006
Location: ZSP/ZPP/ZCW

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Originally Posted by Bob Shiftright View Post

It's the one BMW is/was selling. I purchased it after my first battery was replaced under "goodwill" and I was told I didn't drive the car enough. (Which I freely admit. I don't have the time.) The charger/battery maintainer came from the BMW parts department. It has a BMW PN and a BMW roundel on it (no doubt allowing it to command the price premium over the nearly identical Chinese product sold on Amazon without the BMW roundel.)

The latest iteration of the car's ongoing electronic problems seems to have strained the battery. However, I made certain that it was completely charged before taking it to the dealer for the repair. However, it looks like they kept it in the programming bay over night without putting it to sleep, and after I picked the car up the poltergeists that appeared when my first battery started dying have reappeared. Since BMW doesn't warrant their batteries, I have the choice of either paying BMW $450 for a BMW battery with no warranty, or paying $200 for an Interstate battery with a warranty. The choice seems so obvious that it shouldn't even merit any discussion.

I have not been impressed by either BMW batteries or BMW customer service at this point. Interstate, WalMart and Sears are able to warrant their batteries and still make a profit. And I'm happy to pay for a $200 Interstate battery with a 30 month free exchange. Over 2 years, that will cost me about $0.25 per day. $0.12 if it needs replacement in another 2 years.

Note that I can leave any of our Japanese cars for days and days without them being driven and the battery is never a problem.

To be fair, the battery discharge issue seems to be a Porsche problem, too. Electronics just aren't the German car industry's forte.

It's OK if German cars are hard on batteries, I like driving German cars, I can afford it, and I don't have a problem with it. I just want the car to work. So if anyone knows what model Interstate battery will fit in an E91, I would appreciate the information, since posters have indicated that the battery that Interstate lists for the E9x won't fit.
That device looks like a rebranded battery tender, should be ok.

Not sure what your issue is specifically, but my car has sat 6 weeks in the garage, in the winter, and fired right up. So imho German cars are not "hard on batteries." The battery doesn't care what country the vehicle is from.

It seems like a lot of people have a problem with paying $280 for an OEM battery installed and programmed. I suppose there are those who saved $80 to $100, and those who didn't have luck as such.

Again, it's not rocket science. If a battery is only lasting 2 years, it's not the battery, it's something else.

I think you need to consider that having an OEM battery fail every two years is not the norm. but I can see that you want to try Sears or Wal Mart, can't hurt. If it works out for you, I still believe that BMW batteries last more than two years.

Have you load tested the battery that failed at 2 years?