New answers tagged


Lenovo ADL170NLC3A has an Energy Star V (ES 2.0) rating. Energy Star states to get that rating for nameplate output power ($P_{no}$) > 45W, the Minimum Average Efficiency in Active Mode ≥ 87%. At nominal conditions of 170W, 20V @ 8.5A, and a minimum efficiency of 87% implies 195W input. So worst case, the ac charger consumes 25W. The AC adapter is a ...


The 2.5 A current is the peak in charging up the internal high-voltage DC capacitors for the switching power supply. In normal running the input power should be $$P_{in} = \frac {P_{out}} {efficiency} $$ where efficiency should be somewhere between 80 - 95%.


This is a rating label, not a measure of device efficiency. That power brick is definitely not putting out 80 watts of heat because it would melt in short order. You should expect that the device will operate within the expected input voltage, not draw more than the rated input amps, and will not put out less than the rated output power under those ...

Top 50 recent answers are included