Things You'll Need
Instructions
Purchase a set of at least 8 rechargeable batteries and a charger.
Charge the batteries for the amount of time recommended in the instruction manual that came with them.
Insert four of the rechargeable batteries in your Wii Fit board, making sure they are aligned correctly.
Replace the batteries when they can no longer power the board. Charge the dead batteries, so they are ready for use when the other set dies.