There are a number of ways to reduce battery usage while scoring.
-Try setting your device to 'Low Power Mode'
-Under the Apps settings - reduce the timer for the screensaver from 30 to 20 seconds.
-Reduce the Brightness value from 80% to a suitable readable setting.
-Reduce the usage of the GPS Map interface
-Place device in Do Not Disturb Mode
-Ensure other application are closed prior to scoring.