How many watts does the magsafe macbook charger draw?

[compslckr]

I got a nifty looking battery backup / charger for Christmas this year, and have used it to charge my blackberry while driving (normally use car charger, but I figure I would try this thing out).

Anyways, I was wondering how many watts the macbook magsafe charger draws, I know the output is 65 watts, but I would like to be able to charge my macbook with this backup/charger,

The max wattage on the pocket-power is 16 watts continuous or 20 watts for 5 minutes, Could I charge my macbook? or does it draw too much?

 

[Arcygenical]

I would expect it to draw 20% more than it outputs to charge...