RC-20N is for 20pcs AA batteries (battery for wireless microphone systems), while RC-40N for 40pcs AA batteries.
Separate charging status indicator for each battery, flashing means being charging.
Charging is completed within 5 hours and the charging status indicator lights red.
Stop charging if batteries are not fully charged within 5 hours.
Switching the charger’s power OFF and back ON again with fully-charged/ charging completed / batteries inserted will result in repeated recharge of the batteries. Battery life could deteriorate from this repetitive charging.