My country has 220 V sockets and that's what we use for charging our phones. So do the chargers need all the 220v? My question is that does the load take all the current and voltage available from the power source or immediately getting something wrong?

 

My country has 220 V sockets and that's what we use for charging our phones. So do the chargers need all the 220v? My question is that does the load take all the current and voltage available from the power source or immediately getting something wrong?

Hi,

The voltage is stepped down through one or more different ways to supply the device with the correct voltage. The power however will be roughly the same going in as coming out except for the inefficiencies of the step down process circuitry which will need a little power to work too. Typical efficiency would probably be around 80 to 95 percent or so.

 

My country has 220 V sockets and that's what we use for charging our phones. So do the chargers need all the 220v?

No. If you look the power input specifications, you'll see that a range is allowed without affecting correct operation.

I pulled a USB charger at random and it says it accepts input of 100-240VAC at 50 or 60 Hz to produce an output of 5V at 1A.

 

So is the extra power wasted?

Hi,

The voltage is stepped down through one or more different ways to supply the device with the correct voltage. The power however will be roughly the same going in as coming out except for the inefficiencies of the step down process circuitry which will need a little power to work too. Typical efficiency would probably be around 80 to 95 percent or so.

 

So is the extra power wasted?

No.
The circuit only uses the power it needs.
The "extra power" just sits there unused until needed.

 

So is the extra power wasted?

Hello again,

The kind of circuit used is sometimes referred to as a "true power converter" which converts one form of power to another with an acceptable small amount of loss. This means there is a little loss, but it's usually small enough to be acceptable. The loss is typically 5 percent to 20 percent so if you have a 5v 1 amp load (which in terms of power is 5 watts) the loss might be from 0.25 watts up to 1 watt typically in a decently designed circuit.
You can get a real feel for how much power is lost by actually feeling the case of the wall wart. If it feels quite warm then it is probably less efficient than we would like so probably near the 20 percent mark or even worse. Some wall warts dissipate power even with no load and can be as high as 6 watts, so they feel warm even with no load. The variation in circuitry however makes it hard to nail this down without some careful measurements, but the power lost should be low enough to tolerate unless something is seriously wrong with the circuit.

I think the implication here was that the wall wart might lose power based on the difference in voltage from 120v to 5v or from 220v to 5v, so that the power lost would be based on either 120-5=115v or 220-5=215v because that is the difference in voltage, but that's not the case because true power conversion means the power itself is converted from one form to another and in doing so there is much much less of a loss.