This may be a stupid question...

[Man of Harveys]

...but which uses less electricity: charging or running a device off the mains via a normal plug, or doing so via your computer's USB socket?

 

[Les Biehn]

Can you hook up one of those vibrating rubber vaginas to a USB?

 

[Silent Bob]

Presumably the mains, as you don't also have to power the computer.

 

[Man of Harveys]

Can you hook up one of those vibrating rubber vaginas to a USB?

Yes, I have one on now.

 

[Les Biehn]

Yes, I have one on now.

Then who cares how much electricity. Just indulge yourself.

 

[Man of Harveys]

I'm too concerned about my carbon bumprint.

 

[Les Biehn]

I'm too concerned about my carbon bumprint.

I would be more bothered about burning your old chap.

 

[Meade's Ball]

I would be more bothered about burning your old chap.

 

[Rangdo]

...but which uses less electricity: charging or running a device off the mains via a normal plug, or doing so via your computer's USB socket?

I would make the assumption that charging it off the USB would use more electricity since the current has to pass through more components, cables etc. meaning more resistance and energy loss.

Just a guess like

 

[Braders]

I would make the assumption that charging it off the USB would use more electricity since the current has to pass through more components, cables etc. meaning more resistance and energy loss.

Just a guess like

is the right answer

 

[NMH]

Input to output. It'll all be the same. Electricity isn't going to get sucked into resistors and wires and just disappear forever into the air, or get stored there either.

Same for both, is the NMH answer.

 

[The Clown of Pevensey Bay]

Input to output. It'll all be the same. Electricity isn't going to get sucked into resistors and wires and just disappear forever into the air, or get stored there either.

Yes but it turns into HEAT and LIGHT and KINETIC energy, innert?

Most of the USB devices in a catalogue I've just looked in run off twelve volts. If you plug your device into the mains using an adapter it will probably use twelve volts.

It's always much quicker charging my iPod with the mains adapter, though.

 

[Rangdo]

Yes but it turns into HEAT and LIGHT and KINETIC energy, innert?

Exactly. The energy is not lost but it is turned into heat. It is not "sucked into" cables and resistors it is expelled as a different form of energy. The heat that comes from electrical items isn't coming from nowhere, it is wasted electricity (unless it's an electric heater obviously ).

The NMH answer is the WRONG answer

 

[Uncle C]

If your computer is already on then its cheaper to plug straight into the USB port.

To operate directly from the mains will require the use of an extra transformer, with its attendant inefficiencies and energy losses through heat.

 

[Rangdo]

If your computer is already on then its cheaper to plug straight into the USB port.

To operate directly from the mains will require the use of an extra transformer, with its attendant inefficiencies and energy losses through heat.

Surely though if you pass extra current through a hot transformer that is already under heavy load it must be less efficient than using a cold transformer that is under no load?

And that is before you take into account that a mains charger is a transformer with a short length of cable where as with USB the current has to travel down the mains cable, through the transformer and associated cabling, through the circuit boards and down the USB cable. The latter path must be less efficient than the former?

 

[Easy 10]

Oh what does it MATTER ?

 

[Rangdo]

Oh what does it MATTER ?

If only that thought always went through your mind before you pressed the Submit button.......