Be very careful you're able to differentiate between a power supply and a battery charger. The charger for many NiCad and NiMH powered rechargeable devices are nothing more than carefully rated power supplies and choosing one with a higher ma rating than the one the pack was designed for will likley result in overheating, cell life reduction/damage, and be a fire hazzard. Cheap 'chargers' rely on the rated ma output of their power supplies to cause a voltage sag that will stop the charging current gradually as the pack reaches capacity, a higher ma rated pack will keep it's voltage nominal past the safe charing current of the pack and cause heat which destroys batteries and is possible to start fires, this is especially true of lipoly batteries, which experiance overheating 'harder' and their energy density allows thermal runaway to cause the pack to burst into flames when not intelligently charged.