How do I know When My ChessUp is Fully Charged

On the side of the ChessUp (near the on/off switch) you will find a red LED. When plugged in the the charger this light will blink to indicate that the board is being charged. When this red light turns solid the board is fully charged. 

You can also find the charge level by connecting the board to the app. The app might say that the board is 100% charged before the red LED stops blinking. For all intents and purposes the battery is fully charged, but there is a little more the charger is doing to top the battery off.