<VV> Electric costs for electric cars?

[J R Read]

Hey Frank,

I forgot all that electric stuff long ago, but I did not forget that 1800 
watts/4800 watts = .375

I also know that 8 hours X .375 = 3 hours.  Please let me know if I missed 
something on that calc.

I don't know about the rest of the calcs that were in there, but it seems to 
me that if 8 hours for 110/120 volts is correct then 3 hours for 220/240 
volts would also be correct.  Using (your) .48/hr cost for the "overnight" 
charge on 220, the total would be less than a buck and a half for as well. 
3 X .48 = $1.44

Did I forget to take another factor into consideration?  I'm not trying to 
be a smart axx, I'm trying to understand why it would not be cheaper (at 
least quicker) to use 220 VS 110 to charge up.  The 220 would also give room 
for extra charge time - if needed.

Really, I'm still trying to justify (convince myself that I was right) about 
the cost of running 220 to my detached garage in order to heat it (when I'm 
in it) during winter months.

Later, JR

----- Original Message ----- 
From: "Frank DuVal" <corvairduval at cox.net>
To: <virtualvairs at corvair.org>
Sent: Tuesday, November 29, 2011 11:06 PM
Subject: Re: <VV> Electric costs for electric cars?


> Some quick math:
>
> A 120 volt standard receptacle is 15 amp rated. So, the most power one
> can pull from the standard home outlet is 15 A X 120 volts = 1800
> volt-amps, which we will call watts and ignore the reactance part of AC
> circuits. I said simple math...
>
> 1800 watts for one hour of charging time is 1.8 kw hours. IF you pay
> $0.10per kwh, you will pay $0.18 per hour of charging at maximum pull
> from a standard receptacle. Overnight charging would cost $.18 x 8
> hours, or $1.44 per night. Sounds cheap, so what can change? Maybe it
> takes longer than 8 hours to charge your car. Your kwh rate may be much
> larger than $.010.
>
> If you opt for the quicker charge by installing a 240 volt receptacle, 
> then:
>
> 20 amp circuit could be 20 x 240 = 4800 watts maximum. I say maximum in
> both these cases, as usually you design an appliance to draw only 80% of
> the  circuit rating.  4.8 kh for an hour is 4.8 kwh, or (@ $.10 per
> kwh)  $0.48 per hour of charging. Some thing I read say these chargers
> will recharge the car in 5 hours or less. So, $2.50 or less per night.
>
> I guess the real math is to figure the kwh used by the car, therefore
> the real cost of recharging can be calculated. Too much for this 
> discussion.
>
> Frank DuVal
>
> On 11/29/2011 11:06 PM, John Beck wrote:
>> I haven't done the math myself but the figures you see tossed around are 
>> in the single digit cents/mile.  For electric cars to really make sense 
>> (at least until their numbers become to big to matter) the utilities need 
>> to provide incentives to charge them during way off peak hours.  In most 
>> places, he electricity we use in the middle of the night in the summer 
>> costs the power company almost nothing.  Might as well charge some cars. 
>> Peak demands for electricity at 5pm in the middle of summer are very 
>> expensive to cover.  --J.B.
>>