Nintendo will release a new battery pack with significant charge for the Wii U gamepad.
They have listed the product on their Japanese site and have mentioned that it will cost 3,150 yen including tax, and 3,000 yen excluding tax.
It will be released on July 25th and it’s not clear when it will be out in the west. The capacity of the battery is 2550 mAh, which is much higher than the 1500 mAh of the current battery.
The Wii U gamepad is known for a very low battery charge and this should help things a bit.