Join Date: May 2017
Location: Brisbane Australia
I fitted a lithium battery, and am very happy with it. Granted we don't get any days in winter when the temperature is an issue. Even in colder weather, you can 'warm' up the battery by running the headlight for about 30 seconds before cranking the engine. I paid AU$160 for mine including postage via ebay (SSB Lithium Battery BMW G310R). No need for any additional chargers unless you are really draining the battery. The voltage was a bit low when I received the battery, but still enough to start the engine, just needed to go for a long ride to charge it up, haven't had any problems since.
The battery that I got specifically for the 310R was a bit smaller than the oem battery, so you could possibly get a larger higher capacity lithium battery.