In previous BCDC models, the blue wire would be connected to battery positive for BCDC1225 or Ignition for BCDC1225-LV. The new BCDC1225D combines the Standard and Low voltage functions in the one unit. When the blue wire is connected to positive the unit will operate in Low Voltage (LV) mode and leaving the blue wire disconnected will allow the unit to operate as a standard BCDC. The diagram below shows the connection required for Standard or LV functions.
For more information on correct wiring please consult page 9 of the user manual.