Changing the Battery in the Assistant Control Panel
A battery is only used in Assistant Control Panels that have the clock function available and enabled. The battery keeps the clock operating in memory during power interruptions.
The expected life for the battery is greater than ten years. To remove the battery, use a coin to rotate the battery holder on the back of the control panel. Replace the battery with type CR2032.
NOTE: The battery is NOT required for any control panel or drive functions, except the clock.
Source: Daikin (oslo.daikinapplied.com)