S = 20 minutes, M = 40 minutes, L = working until the battery power exhausted.
BATTERY INSTALLATION AND REMOVEL
1. Make sure the power switch of unit is turned off.
2. Press and slide the battery cover (see diagram below).
3. Insert the battery plug into the socket (please check the direction).
4. Place the battery in the battery reservoir and close the battery cover.
5. To remove the battery, please follow step #3 above in reverse.