As One Laptop Per Child prepares to ship its highly anticipated XO laptops in two weeks, it is developing a "supercharger," a mass battery recharger that will draw power from cows and yo-yos to help the laptops run longer. (Australian Joel Stanley is working on the charger system for the XO-1 laptop, read his story here).

The supercharger is a box that will charge 15 batteries at a time, said Mary Lou Jepsen, chief technology officer for OLPC.

The supercharger complements other environmentally friendly battery charging technologies being used or under development for the XO laptop, Jepsen said. Users can hook up handcranks, cows, yo-yos, foot pedals and solar panels to the box to recharge batteries.

Last week OLPC said it was designing a cow-powered generator through a dynamo with a system of belts and pulleys using cattle to generate power.

A typical charge cycle for a laptop battery should be about three hours, Jepsen said. Groups of children will be able to share batteries.

Currently in design, the supercharger will be ready for manufacturing next year, Jepsen said.

A laptop's mileage depends on its usage, so OLPC designed an environmentally friendly laptop that could work with a rugged, low-power battery, Jepsen said. The laptop's specially designed lithium-ferro phosphate battery consumes between 2 watts to 8 watts depending on usage, Jepsen said. It lasts five years and works in environments up to 100 degrees Fahrenheit (37 degrees Celsius), Jepsen said.

The XO batteries do not work on normal laptops, which can sap up to 40 watts of power depending on usage, Jepsen said.

The XO is also the first laptop that uses only alternative energy, Jepsen said. Low-cost solar panels are great as a power option where there is plenty of sunlight, Jepsen said. Energy is especially scare in developing nations, so the laptop will hopefully pass on energy preservation lessons, which could help preserve battery life in the XO, Jepsen said.

The laptop goes into manufacturing this week after three years of design experimentation and attempts to reduce manufacturing cost. It will first be offered in two weeks to consumers in the Give 1 Get 1 program, in which two laptops can be purchased for about US$400, with a user getting one laptop and the other being donated.

"We're exhausted, but exhilarated," Jepsen said.