USB cable or 'phone charger?

Quaint1

More of a theoretical question really, but I thought I'd ask it here!
At the weekend I bought a USB cable (from Poundland) that allows you to charge your 'phone from USB; it has the appropriate Nokia plug I need and, as I recently broke the normal mains charger for the 'phone, I thought this was a good idea.
My question: which is better, the proper charger, or the USB cable as far as power consumption is concerned? Obviously, there is enough power going through the USB to charge the 'phone, but am I using less power plugging it into the computer (which would be on anyway) than having the computer on AND charging the 'phone on a separate charger? Speed of charge isn't an issue; I'm just wondering if the USB cable is a little bit more of an energy saver!
Au Res.,
Paul

amcluesent

The power draw is so tiny it's impossible to say. Phone chargers take 5-6W, a PC is drawing maybe 250W in normal use. Leaving a light on from 30 minutes will completely overwhelm any savings by changing USB chargers.

kwikbreaks

I doubt that there would be much difference so long as the PC was going to be on anyway but as a full recharge is likely to take a couple of hours or so there is always the temptation to leave the pc on to finish the charge when you may otherwise have turned it off and that is going to use a lot more than the phone charger.

Bikertov

Overall, the phone itself will take exactly the same amount of power to charge it fully, regardless of where that charge comes from.

However, if it is from the laptop, you need to get that power into the laptop in the first place. As that is not a 100% efficient process, it is therefore less efficient to charge via the laptop than directly from the mains.

Also, as the laptop will be on, it will itself be using power for the screen, hard disk etc.

But at the end of the day, the power we are talking abount is so minimal in the scheme of it, that the power used does not really matter. You can, though, get a Nokia mains charger from Amazon etc for around £3, so it might be more convenient to do this.

Quaint1

Thanks for the responses! It was more of a theoretical question - when I have the computer (a desktop, not a laptop) on, (which is rather a lot as I do a lot of stuff on the computer in the evenings) it seemed to make sense to charge the 'phone from it at the same time and save having two devices plugged into the mains at the same time.
Au Res.,
Paul

Apples2

But it still has to suck the same amount of wigglies from the wall socket whether there is a PC in the way or not.

All your elastic trickery in your house is coming from the same couple of wires in the fuse box.


Ahhh! what on earth are we discussing this for?? I'm getting out more!!

p.s
How much was the USB cable??