Victron energy Buck-Boost DC-DC 25A Manuel page 9

Connection
Simplified diagram:
Microcontroller
temp
Sensor
3-axis
Buck/boost controllers
OUT GND
Converter
GND
output
CAN Bus connection
Connections:
Relay driver
1
2
IN
Converter
input
USB connection
OUT
in/out
in/out
IN : Converter input (alternator/starter battery)
GND : GND (chassis)
OUT : Converter output (extra battery)
Pin 1 : Input/output (purple wire)
Pin 2 : Input/output (green wire)
When Pin 1 or Pin 2 is being used, use the resistors
supplied to ensure safety.
This is no longer necessary in the most recent models
(recognisable by their ridged housing).
GND
IN
7