Except that the manual here is rather incomplete.

The general rules for Li Ion batteries are that that you should not store them in a "discharged" state (or you risk falling below the threshold at which the protection circuitry will no longer allow them to be recharged), you should charge them when they have run down a bit (not topping them off if they have not been used), and that you should store them in a cool place.

You don't need to be obsessive about NOT charging them (as you would with a NiCad) but for best battery life, charge them only when they need to be charged.