#21
Here is an electric bill formula.
cost of bill = rate in dollars X Kw hours
rate in dollars = what your electric ultility is charging you.
ex: in Los Angeles it is .08 cents for 1Kw hour
Kw hours = how many watts you are using in an hour
ex: a 60 watt light bulb would be 60 watts divided by 1000 = .06 KW
OK, lets figure our bill for this 60 watt light bulb

cost of 60 watt light bulb = rate in dollars X Kw
cost = .08 cents X .06 (1 hour) = .0048 cents for every hour the 60 watt light bulb is “on”

GM Volt at 120-volt charge
cost = rate X Kw
cost = .08 X (120-volt X 20 amp)
cost = .08 X 2400 watts (2400 divided by 1000)
cost = .08 X 2.4
cost = .192 cents for every hour
GM volt will take overnight to charge, so
cost = .192 X 10 hours
cost = $1.92 for a “full” charge

GM volt at 240-volt charge
cost = rate X Kw
cost = .08 X (240-volt X 30 amp)
cost = .08 X 7200 watts (7200 divided by 1000)
cost = .08 X 7.2
cost = .576 cents for every hour
GM volt will take 3 hours to charge, so
cost = .576 X 3 hours
cost = $1.73 for a “full” but “quick” charge
cost at 3.5 hours is $2.02
so you can see how they are very close in cost.