A new charger developed by Sanyo makes replenishing the batteries in Nintendo Wii controllers as easy as placing them in a cradle.

The device, which will go on sale in Japan in August, consists of a rechargeable battery pack that replaces the batteries and battery compartment cover on an existing Nintendo Wii remote control, and a charging cradle and AC adaptor. In both the battery pack and charging cradle are coils of wire that, when brought together, enable energy to flow by induction from the cradle to the battery pack.

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Nintendo said a fresh set of alkaline batteries should last for up to 35 hours, but with gameplay sessions often occupying several hours at a time, most users face having to change batteries several times a year.

The Sanyo charger will completely charge a remote control in a little under four hours, the company said.

The basic set of the battery pack, charging cradle and AC adaptor will cost around ¥5,500 (£25). Additional cradles and battery packs will cost around ¥2,500 each. A single AC adaptor can be used to charge up to four remote controls but they won't charge simultaneously. The charger closest to the adaptor will first replenish its controller and then the next one will begin charging.

The charging system will go on sale in Japan on August 25. Sanyo doesn't have any concrete plans to put it on sale overseas at present.