This is a 3pin 1.5mm video power cable which is DC 3V to 6V input and DC 10V output for camera. It is very suitable for FPV. You don’t need to use a spare DC 10V li-ion battery to power the camera. You can use this cable to convert camera’s DC 10V power to DC 3V to 6V power.
Please ensure correct connection via pin definition, otherwise it can't be used normally.