his product can transform the unstable 18-40V DC power supply into a stable 13.8V (the input voltage will affect the output voltage floating between 12-13.8V as the allowable range) DC power supply output, which has automatic protection functions such as overvoltage, overcurrent, overtemperature, short circuit, etc., and can work normally after returning to normal conditions (especially for ships and vehicles with more than 24V power supply)