SMAKN&reg; 25W USB smart thermostat adjustable constant current electronic load / charge treasure detection test instrumentation aging discharger Operating voltage: DC3.5-21V (compatible with Qualcomm QC2.0 of A / B protocol 5V / 9V / 12V / 20V), support Qualcomm B protocol. Constant discharge current: 0-4A adjustable. Current Operating error: not more than 2% + 3mA. Continuous discharge power: 25W (20V at high pressure, the continuous discharge current as possible less than 1A, in order to avoid a power overload caused by excessive discharge FET). Smart Thermostat start-up temperature threshold: 55 degrees (above this temperature the fan automatically turns on the fan automatically closes below this temperature).