The X4AC charger (European charger) must be configured for charging EVO3x battery after each power cycle (every time the charger is powered off). If you're getting a "CELL ERROR" or "BATTERY NOT DETECTED" error when attempting to charge, you may need to update the charger settings.
To update the settings:
Select LiPo BATT in top level menu for a given channel. Press ENTER.
Press INC/DEC until you see LiPo CHARGE. The display must not read LiPo BALANCE CHG. Skycatch batteries are self-balancing. Press ENTER.
Press ► until amp value is flashing. Change to 3A.
Press ► again until voltage value is flashing. Change to 6S. Press Enter.
After seeing CONFIRM(ENTER), press ENTER to start charging.