Improve the range of an E-zip trailz ebike

I am interested in seeing how to improve range of the batteries on my e-zip trailz. Would a different battery charger help? I am using the standard charger for both battery packs. I've heard there is a charger which helps de-sulfate the batteries for longer range and durability. Also I am interested in changing the batteries in my pack to another type. Does anybody know the cost of changing the batteries and how to do it?