Product description NWANSI DC 12V to DC 48V Boost Power Converter Regulator 3A/4A/5A/6A/10A/20A/30A Product Wiring Instructions The red cable at the input end connects to the positive "+" terminal of the power supply. The black cable at the input end connects to the negative "-" terminal of the power supply. The yellow cable at the output end connects to the positive "+" terminal of the device. The black cable at the output end connects to the negative "-" terminal of the device.