I used the BMW battery charger that I purchased when I had my 2007 K1200GT on my new K1600GT when I was away for a month. According to the dealer and the spec numbers in the owners manual it was supposed to work perfectly with the new bike. Anyway it doesn't work worth a #$%@**. The dealer told me this morning that BMW changed their recommendation because there is an upgraded electronic canbus on the new bike that charging it with anything but a spec'd charger for the 1600 will cause electronic problems. I had to tow the bike to the dealer today because it won't start and seems to have some serious electonics issues.