General question about amps....output more amps than input?

[tomtom123]

i was just looking at my laptop charger today and the input to the charge is 100-240v, since i live in the USA, the input is 120v. also listed in the input is that it takes 2 amps. Now for the output, it outputs 19.5v and 4.62 amp......REally curious how you can take 2 amps and output 4.62? anyone knows?

 

[nechaus]

Well its stepping down the voltage which allows you to output more amps

1 amp @ 120 volts is about 120 watts
10 amps @ 12 volts is about 120 watts
sorry I'm not the best at explaining it, this may help you a little

 

[dogman dan]

So up to 240 watts going in, and perhaps about 100 watts going out. Some of that extra making some heat of course.

Now you are wondering if it's really that inefficient. Likely it's not, but only with a wattmeter on both ends can you really measure what's actually going in and coming out the other end.

 

[gogo]

http://en.wikipedia.org/wiki/Buck%E2%80%93boost_transformer
Also, are you aware that eBike controllers are typically configured to output up to 2.5 times the battery amps to the motor?