Instructions
Turn on the Wii Remote and the Wii.
Push the Wii Remote's "Home" button, which is located in the middle of the controller between the "-" and "+" buttons. This will open the "HOME Menu."
Point to the Wii Remote graphic in the menu and select it.
View the Wii Remotes' battery levels on the bottom of the screen; it will display the battery levels of all the Wii Remotes currently connected to the console.