Abstract: A plurality of rechargeable batteries are provided as part of an electronic system that includes an electronic circuit which controls periodic charging of the batteries and allows selection of the output voltage over a given range. The system is preferably packaged in a shape to be easily integrated with a carrying case, such as a briefcase, and/or to physically match a specific type of portable equipment, such as a notebook computer. In one embodiment, the batteries and circuitry are included in a wrist rest structure of a type used with portable computer keyboards. In other forms, the power supply is useable with a large number of other specific items of portable electronic equipment, such as portable video and telecommunications equipment.