TOKYO (AP) -- A new rechargeable battery pack made by Sanyo Electric Co. will allow Nintendo Wii gamers to keep their controllers juiced without buying new batteries.

The wireless Wii controller normally uses two standard AA batteries that are installed under a cover. Nintendo says alkaline batteries can last up to 30 hours, which means that devoted gamers must buy lots of new batteries.

Sanyo's device replaces the batteries and cover with a rechargeable battery pack, allowing the controller to be charged by simply placing it in a charging stand. It charges through magnetic induction, with no plugs or battery swaps needed.

Sanyo says the battery pack can be recharged in less than four hours.

It says the device will go on sale in Japan on Aug. 25 and is officially licensed by Nintendo. No plans for overseas sales were announced.

Nintendo's Wii game console has been a smash hit since its 2006 release, in large part due to its unique wireless controller. The wand-like controller is equipped with motion sensors that allow users to control game action by jabbing and swinging it through the air.

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