How much does it cost to charge a mobile phone for 8 hours?

Question

we are constantly reminded by the save the earth lobby not to leave such things as mobile phone charges switched on wasting electricity when theye're not in use. but just how much electricity is being used to charge a phone overnight for 8 hours? if the charger (a nokia ac5) has a output of 5v, 800mA and electricity costing 15.54p per KWh ????

Answer 1

You already have two good answers. Betty and Dana1981 are both correct.

Betty said approximately 30 watts.

Dana1981 said 0.032kwh which equals 32 watts.

Dana showed his calculatons and Betty didn't show hers.

No point in me doing it again.

Answer 2

Power = Voltage * Current = 5V * 0.8A = 4W

Assuming the charger were using its full output for all 8 hours (as Betty notes, it shouldn't), it's using 4W * 8hr = 32 Wh = 0.032 KWh.

Cost is 15.54p/KWh * 0.032 KWh = 0.5p

The point of the "save the earth lobby" is that if a large number of people eliminated as many small wastes of energy as possible, it would add up to a significant savings.  Each individual saving (such as your cell phone recharge) is small, however, as you can see by this calculation.

Answer 3

Very little.

If that charger was running at full power for 8 hours the cost would be less than one half cent.

At full power for 8 hours your charger would use approximately 30 watts of power.

At 15.54 cents per kilowatt hour, that is a little less than one half cent.

Your charger is designed to reduce its out put as you approach full charge, so it will not run at full power for 8 hours unless the battery is defective. So your actual use of electricity will be less.

Answer 4

I use a solar power charger