diffrent voltages on batteries are quite common, but usually aren't much of a problem. Alkaline's puts out 1.5 volts, rechargeable's like NiMh and NiCa put out 1.2 Volt. So no over loading issues there. But there simply isn't a rechargable type of battery that matches the voltage of an lithium battery. Lithium Ion's are the next best thing, but they are higher power.

The charger on that website are made in diffrent version, for diffrent versions of batteries. I have seen both 3.0 and 3.7 charger versions with the same exterior.