Sanyo has developed a rechargeable battery that can be supplied charged. The new battery enables charging at the time of manufacture.

The new battery is a nickel metal hydride (NiMH) cell of the type commonly found in many portable electronics products - but with a key difference. Typically, NiMH batteries lose their charge over time if they are not used. Consequently, the time gap between manufacture and sale means it's not feasible to supply them charged. Sanyo's new battery loses energy much more slowly when unused.

Sanyo claims its new battery loses about 15 percent of its charge after a year of non-use, compared with competing batteries that lose almost all of it over the same period.

The technology, which will be used in an AA battery that will go on sale in Japan in the middle of this month, is the first product to result from Sanyo's 'Think Gaia' corporate restructuring plan. Under the leadership of chairman Tomoyo Nonaka, Sanyo is attempting to refocus around environmentally friendly products.

Sanyo will promote the batteries as a replacement for throw-away dry cell batteries, of which around 40 billion are disposed of worldwide each year, according to industry figures cited by Sanyo.

The batteries, carrying the 'Eneloop' brand, will go on sale on 14 November. A pack of two AAs will cost ¥1,155 (around £5.66). They will also be available in packs of four and eight, and with a recharger. AAA-size batteries in the same range will go on sale in Japan on 21 January 2006, and cost ¥945 (£4.57) for a pack of two.

The company estimates the new batteries will reach the end of their useful life after they have been recharged about 1,000 times. Sanyo said the batteries are environmentally friendly and can be recycled.

Although better known for its electronics products, Sanyo is a major manufacturer of rechargeable batteries. The company claims a 45 percent world market share for laptop PC and mobile phone batteries and a 55 percent share of the digital still camera market. About 60 percent of rechargeable batteries sold in stores worldwide are manufactured by Sanyo, according to the company's figures.