"You can USUALLY convert a 1600 to a 1602. However there are some 1600s sold where the terminal that accepts the second power cord is not functional so you cannot install the second power cord. Unfortunately, there is no way to tell by looking. During the assembly process, sometimes the little screw in the power-input terminal gets stripped. If that happens then we make the controller a LOR1600 because we only need one power feed. If the terminal on the unused power feed in your unit is OK (the screw is not stripped) then you are good to go."