I have a lithium battery in my Bonneville it's a good 4 years old and considering I only start it once or twice a year the battery has never let me down. And there is no charger attached either. The instruction said to put a charger on it every 6 months but I really have only being doing the recharge every year.
When it came time to buy a battery for the Rocket the supplier said not to get a Lithium if there is a constant draw on the battery when the bike is standing so I went down the Dynavolt path. SO far no issues.