A large 3.5 inch touchscreen, 3G and lightweight are the perfect ingredients for a poor battery life. Sanwa Japan has introduced the 400-BT001 a rechargeable battery which gives the iPhone-3G an additional 3.5 hours of talktime, 7 hours of video playback and 36 hours of audio playback. The 1,200mAh Lithium Ion battery comes with a retractable USB cable and a LED which indicates remaining battery life. The unit measures 46×72×13mm and weighs 50 grams. It is scheduled to go on sale in Japan by end of July for 4980 Yen ($ 50).