By the way -
There are some interesting threads on batteries here: http://advrider.com/forums/showthread.php?t=415604
cntrl+f battery and you'll get right to them on the sticky.
I read through a few on my phone this morning and I came up with a few nuggets of useful information and extrapolated a bit to our common problem:
1. the 800gs and beemers in general have a low charging voltage - that doesn't play nicely at lower temps when batteries require higher voltage to charge. Add on a few accessories grips etc and over short rides you're not returning your battery to a fully charged state. I can't find the thread with the chart at the moment. will try to add it here.
2. the 800 has some nominal current draw even with the key off. Batteries also have an inherent "degradation" over time this can add up to a not insignificant amount if you are just starting your bike instead of taking it for a spirited ride at RPMs high enough to charge fully.
3. there are entire threads on how much the 800 battery sucks, fails, is replaced under warranty etc. I never found out whether there was a part change in newer models.
4. found some data backed up my Li-Ion statement earlier - It makes a great Southern state battery but wont work nicely in the colder climates. Also I learned that Li-Ion batteries remain at full voltage output until they die whereas a AGM or acid battery will slowly degrade giving you some warning that the battery is tired. Tremendous savings in weight is the tradeoff.\
Hope this helps!
Originally Posted by h2only
thanks for the info, it has been below 30 degrees for a solid 2 weeks here. For some reason I always decide to start my stored cars, bike and the such on the coldest days of the year.