The function of the controller is to protect the voltage overshoot and discharge.
When the battery voltage is too low, the controller to stop output; after the solar panels charging, the battery will return to 12.6 v. It is a natural to output.
12.6 v is to restore the discharge voltage.
When the solar panels to recharge battery float charging voltage can be achieved. It will stop charging. This is called overshoot protection.
After the battery discharge, the battery outside will flash, this is to remind the user, the configuration is not reasonable, it need to take battery connection.
The controller normal voltage of 10.8 v to 13.7v. This two voltage fluctuation, you can be set manually.