Aging battery question
 

My previous BMWs have all needed a new battery at around the 4-year mark.

My current 2 is at 5 years with a service coming up. Does it make sense to go ahead and do the battery change prophylactly? The top on the convertible seems like it would be an extra draw, particularly when opened/closed without the motor running, which I sometimes do…

I don’t drive this car at highway speeds very often. It does get used for frequent shorter trips in nice weather.

I usually get 7 years or so in a car I’m using regularly.

Do you have it on a tender? I'd do that if you don't have one, and not worry about the battery until it dies.

I don't. But I should...

I mean, it's not a terrible idea to get it replaced before it dies. You've probably only got a year or two left, particularly given that it sits a lot. That's not that much, vs. the inconvenience of dealing with it after it dies. Especially when that necessitates a service visit.

That is exactly my thinking...

I did that with our LR4. They are known to cause all sorts of weird electrical gremlins in that car when they are low. I swapped mine out at 5 years even though it worked perfectly. Most folks were forced to change theirs at 3-4 years, so I was lucky enough to get 5 and changed it.

I would do a battery in a BMW, Mercedes or Audi at 4 years. I just did batteries in my E38 and 997. Both are/were on BatteryMinders when not being daily driven, but the batteries these days are NOT what they used to be. The lead has to be 100% recycled now - no new automotive batteries sold new in US or Canada that are not that way.

One thing my mechanic recommends is to use AGM for 'regular' cars now. He has seen many 1 or 2 year old regular style batteries pack it in while the AGM's seem to do a bit better. I got 15 years out of the AGM in my Mustang (before it died) and were working with 7 or 8 years out of the other cars till I noticed them getting weak. The batteries in the PSD were 8 years old and starting to get weak as well. So - I bought new batteries the end of last year. 5 or 6 batteries... LOL. All AGM by the way...

YMMV of course

I should note that Costco Interdtste batteries have done well by me. Great pricing, fantastic exchange process. I wish the warranty was a little longer (36 months now), but at their pricing, I’m good.

I am a lame-o who has the dealer do the work, but thanks folks. Confirms my thought that I should go ahead and do the swap.