DC-DC charger troubleshooting

Vehicle start battery draining when parked

If the vehicle's start battery is draining when the engine is off, this is caused by incorrect wiring of the yellow ignition signal wire in the 4-pin signal plug.

The yellow wire is a signal input. It should only receive 12V power when the vehicle ignition is in the ON position — this tells the DC-DC charger to activate and begin charging the DCX battery. If the yellow wire receives constant 12V regardless of ignition state, the charger runs continuously and drains the start battery.

Resolution — ignition wire fault

Verify the yellow wire is wired to a switched ignition source — a circuit that only carries voltage when the ignition key is turned on.
Check that the red and yellow wires in the 4-pin signal plug are not shorted together. Red is the power supply wire and must not be permanently connected to yellow.
As a temporary measure, unplug the Anderson connector between the vehicle and caravan whenever parked to stop all DC-DC charging activity.
If a short inside the plug is suspected (both red and yellow showing 12V with no load), contact OzX Corp support — a replacement plug and wires can be supplied.

DC-DC not showing charge on BMS display

When DC-DC charging is active, the BMS should show a negative amp value. If it shows zero or positive:

Confirm the EXT CHARGE button on the top panel is illuminated with a green LED. Press it to enable if off.
Confirm the blue SB50 Anderson plug is firmly seated in the EXT CHARGE port on the front of the DCX unit.
Confirm the vehicle engine is running — DC-DC charging requires the alternator to be generating power.
Check the 100A fuse on the DC-DC charger supply line is intact.

Connecting a solar blanket via DC-DC

A solar blanket cannot be connected directly to the DCX system. It must first pass through a 48V MPPT solar charge controller. The DCX External Charge Port (blue Anderson plug) accepts 48V input only. A solar blanket outputs 12 to 24V and must be converted to 48V by an MPPT controller before entering the system.

If both a DC-DC charger and a solar blanket MPPT are used, both use the same External Charge Port. You will need to manually swap the Anderson plug between the two charge sources. For a permanent dual-source installation, separate wiring with dedicated fuses is recommended — contact OzX Corp support for wiring guidance.

DC-DC charger requirements

The DC-DC charger connected to the DCX system must meet these criteria: isolated power supply only, Li-ion CC/CV charging profile, maximum charge current 50A, supply line fused at 58VDC or greater, float voltage 58.0VDC. Only OzX Corp approved DC-DC equipment should be used.

Need help? Contact OzX Corp support: 0493 980 869 | support@ozxcorp.com