Sega Master System / Mark III / Game Gear
The Sega Rechargeable Battery Pack was Sega's first attempt at making a rechargeable battery for the Game Gear.
The Rechargeable Battery Pack could be clipped on to your belt, increasing the Game Gear's battery life to about 7 hours.
The Rechargeable Battery Pack was criticized for its weight and bulkiness.
The Rechargeable Battery Pack had a Sanyo Cadnica 7.2v 1600mah Ni-CD battery in it.
Due to the fact it was a Ni-CD battery, and not a Ni-MH battery or a Li-ion battery, most of these battery pack units don't work any more, and need to have the internal batteries replaced with an equivalent unit.