o Electric Co., Ltd.Battery charging apparatus, power supply, and attachment for connecting different types of battery packs to a battery chargerUS5621299 *14 Nov 199415 Apr 1997David A. KrallRechargeable battery power supply with load voltage sensing, selectable output voltage and a wrist restUS5691623 *18 Mar 199425 Nov 1997Tsantilis; EleftheriosBattery charging system, stepping and interactivel