If my cell phone battery is completely dead, how much will it cost to charge it (if the battery is 2000 MaH?) Basically, how many 'units' of electricity will it take to fully charge the phone?
2007-10-28 09:35:15 · 2 answers · asked by Johnny 3 in Science & Mathematics ➔ Physics
What you're calling "MaH" probably should be "mAh" = milli-Ampere-hour.
The amount of charge in 1 mAh is:
1e-3 * (C/s) * 60*60 (s) = 3.6 (C)
So 2000 mAh = 2e3*3.6 = 7.2e3 (C)
(Of course, it has equal amounts of positive and negative charge! But they're chemically "separated".)
2007-10-28 11:36:46 · answer #1 · answered by ? 6 · 0⤊ 0⤋
Look at the battery voltage and calculate the amount of energy needed to charge it. Get the number in kilowatt-hours. The average cost per kwh of electricity in the US is in the range of 15 cents. Derate that by probably 60%, since you don't get as much energy from a battery as you put into it. Derate that by another 70%, since AC chargers for cell phones are quite inefficient. Add an unknown overhead to that if you leave your phone charger plugged in even when you're not charging. Document all the assumptions you make in your calculations.
2007-10-29 01:22:52 · answer #2 · answered by Frank N 7 · 1⤊ 0⤋