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laptop power supply current data question.

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vincew

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Hi, I have noticed that my laptop power supply is rated at 100-240v 1.7A, 19v 3.42a 65w.

looking at the input 240vx1.7A gives 408w however the output is only 65w.

as far as i understood watts were watts, i am sure the psu is not glowing with the spare 300+ watts

can someone please explain where i am going wrong with my thinking?

Cheers

Vince

just wanted to add that i put it on a watt meter and it never pulled above 51 w
 
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if you consider 100v then 170Watts.

it is according to requirement of circuit, battery and power available. that these specs should meet at least for proper operation.

- - - Updated - - -

if you consider 100v then 170Watts.

it is according to requirement of circuit, battery and power available. that these specs should meet at least for proper operation.

- - - Updated - - -

you must check the amperes that are flowing while charging through 220Vac.
 

To be able to calculate the input wattage of your PSU, you need to know your Power Factor, if you're using two multimeter to perform voltage and current measurement then your result will be in VA not Watt.
 

I have a plug in meter that measurs watts, 13a plug one side 13a socket the other, I just do't understand why the input is rated at 408w (by calculation) but the output is only 65w (as stated)
 

Your specification is not given in watt but in Volt and Ampere. So doing the math of V x I is wrong if you want to know what is the maximum power. Refer to post #3.
 

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