BMW offers Gel batteries as factory replacements. AGM batteries is the way to go vs wet lead acid. besides not worrying about spilling acid if your bike tips over. gel cell batteries have a slightly lower charge threshold. one can damage a gel cell by using the wrong charger.
if taken care of by not letting battery drain too low. I've had AGM batteries last 5+ years.
AGM cell has a very low self discharge (aprox. 3% per month). providing your bike doesn't have a parasitic drain. AGM doesn't need a battery tender over the winter.
LiFePO4 batteries if you've got spare $$$ and wish to drop 10lbs or so.
_cy_ screwed with this post 11-01-2012 at 04:49 AM