Product Features:

• Rechargeable lithium-ion battery pack - up to 30 hours of play time per charge.
  Unique AC port relocator allows easy charging of the battery pack. Play and charge simultaneously.
• Detachable AC cord for wire-free play. Plugs into any wall outlet - faster charge than USB.
• Battery pack conveniently charges while inside the Balance Board - no need to remove it once it is installed
• Convenient LED charge / battery indicator

View Wii Fit Energy Pak details