Can power switch automatically from AC adapter to battery in the SK602 QH system?

No, the power for the SK602 QH system can not switch automatically from AC adapter to battery.

The SK602(G) can be operated with AC adapter alone, or on batteries alone. 

It cannot switch automatically from AC adapter power to battery power when AC power is interrupted. 

You have to remove the plug from the receiver so that the receiver can run on battery power.