Hairy_Lee said:ive come across notebooks that draw 6 amps on a 12v supply (while also charging)
in this case thats a total draw of 72 watt, now obviously a lot of this is going to the battery but i think 20 watts is a fairly low value with this in consideration... if you're looking for values for a specifc notebook then you should check the manufacturer's information for that model; they should be able to provide you with the information you need