Abstract: A replaceable cartridge type high speed nickel-cadmium battery charger comprising a base, a circuit board, an upper cover, and a replaceable charger cartridge, in which the base has a hollow interior space and a round hole in the middle; the circuit board with circuits on it is assembled within the hollow interior space of the base; the upper cover has a plurality of convectional radiation holes on the left side of its upper surface, a LED indicator at its left edge, and a replaceable charger cartridge chamber on the right side; and the replaceable charger cartridge has a battery chamber, two conductive metal plates at the front side and a lock hole on the bottom so as it can be placed in and removed from the charger cartridge chamber, and locked to the base by means of a bolt passing through the round hole in the middle of the base to the lock hole.