Replacement Battery for Nintendo Wii U Gamepad Extended 3600mAh 3.7V + Tool | eBay
Replacement Battery for Nintendo Wii U Gamepad - HHD10221 at Batteries Plus
Nintendo Wii U Teardown - iFixit
Amazon.com: Battery Replacement Rechargeable Battery Pack for Wii U Gamepad, 3600 mAh Battery for Nintendo Wii U Gamepad Remote Controller : Video Games
Guide to the Best Wii U Replacement GamePad Battery - Nerd Techy