The D250 & Smart Pass System can work in many configurations. It's ability lies in the configuration to charge start & house batteries from dual input sources and offers low voltage disconnect on non-essential devices via the CTEK Smart Pass.
The units features include Maximum Power Point Tracking (MPPT) controller
Temperature Sensors
Low Voltage Disconnect
Reverse Charging Cycle from house batteries to start battery
equalised voltage for solar panel input with alternator on and much more.
The system is implemented as per situation and may require only the D250S Dual or require the D250S Dual and the Smart Pass. See D250S
owners manual for clarification. Smart Pass manual
click here