How to calculate charging cost ?

Many posts here provide example calculations...
1) Depends on how far you can get on a charge...In the winter I was getting low twenties, in the summer it was low thirties.
2) Depends on the price of gas. It's running around $2.60 near me these days.
3) Depends on how far you can go on a gallon of gas. I was getting low 50's in the winter and low 60's in the summer.

A Prius prime takes about 6.3KWh of electricity according to the meter on my L2 charger. Others have confirmed similar values and some report that L1 charging is a little less efficient. At 0.25/KWh, that would translate into $1.58 to charge.

Using a middle value of 27 miles/charge, that equates to $0.0583/mile using electricity.
Using a middle value of 57 miles/gallon, you get an equivalent of $3.33/gallon.

If gas is less than $3.33, it is less expensive to use gas than charge...But EV operation is fun and many of use believe worth paying a little extra for...But only a little extra...

 

pennies per mile are about the same for you, but you pollute much less driving the car as an EV

If you want to get the most meters out of each penny as possible, drive EV in the city and HV on the highway.

 

Your cost in electricity to travel the same distance as you'd get with one gallon of gas. Spelled out, formula wise...

your gas-only MPG / your normal EV-only total range * kWh to charge your Prime * your cost per kW

placing my own numbers in
56 / 28 * 6.33 * $0.072 = $0.91 to travel the same 56 miles as one gallon of gas

For me, it is well worth it to plug, as gas is about $2.50 here, or less if I shop around. If it is close, it may depend on how clean or dirty your electricity is. Ours isn't very good on average. Our town has a community-wide purchase plan that we opted into, plus we could choose the regular ComEd mix of regional supply (kinda dirty but cheaper) OR going with a totally green supply. The costs were $0.0685 vs. $0.072 per kW. That's the first year they offered a choice within a choice. We pay the higher price as it is a vote towards a cleaner mix, even if our actual power isn't 100% green. The more people sign up for the green option, the greener it all gets overall. We thought it was the responsible thing to do even though it wasn't the least expensive.

Some other considerations are the time and expense to travel to and from a gas station, smelling the fumes there, and knowing what comes out of the tail pipe is toxic as you use gas. Frankly, even if electricity was a LOT more than what we're paying here, electric has so many more advantages both personal and for the environment. And just having a car that is (partially) electric, is a big statement in and of itself vs. the world of dying ICE engine vehicles production.

 

My numbers would be..

(Winter) 52 / 23 * 6.2 * $0.12 = $1.68
(Summer) 60 / 30 * 6.2 * $0.12 = $1.49

I'm not actually sure about the 6.2KWh/charge number in the summer...I installed the meter on my line in December so I haven't had a chance to measure per-charge with hot weather. Right now I see charges anywhere between 6.1 and 6.3 so I averaged to 6.2

I see a good bit of variability in distance. On the really harsh days of January, I might not have even hit 20 miles on a charge but was likely also below 50 on MPG...(I don't bother tracking that closely)...But that would put my cost equivalent closer to $1.85 in the worst cases...I also think in really ideal conditions I can do better than 30 in the summer. The gauge often predicted 32-34 last August but I didn't see actuals get much over 30.

In general, I would claim $1.60 +/- 10% depending on driving and weather conditions...maybe up to 15% for the extreme conditions.

 

From @DavidA post just prior...His equation is:

I was just adding values to his equation.
During the winter, I'm seeing about 52 MPG with gas and 23 miles per charge
During the summer, I saw closer to 60 MPG average and at least 30 miles per charge with my normal driving.

 

His equation broken down:

1. Calculate the cost to charge the battery from empty to full
2. Divide (1) into the EV range to calculate the cost to travel one EV mile
3. Multiply (2) by MPG

 

There is another consideration, and not in the formula. One's spouse opens the electric bill, and asks why the previous month is higher usage than last year. To appease the inquiring spouse, you offer to go out to dinner to diffuse the situation. Thus, adding to the cost of charging by about double.

 

I realize this is humor, but I sure hope that your spouse noticed the reduction in petrol use and cost.

 

This is one of those somewhat imponderable questions because there are a lot of variables including such uncontrollable things as weather, ambient temperature, driving style, trip length and traffic conditions.

I was also wondering about this, so I installed a watt-hour meter to measure power consumption of my home EVSE unit.

There is a more detail explanation and description here: https://priuschat.com/posts/2694709/

The bottom line is that the difference between electric and gasoline cost per mile may be only pennies, one way or the other. As long as they are reasonably competitive, I will opt for running in EV mode both because of environmental concerns and because of the pleasure of smooth and quite EV driving.

 

She recently replaced her 2002 gas car with a Lexus CT200h, and went from 20MPG to 48. She's also a wee bit jealous of the hundreds of MPG my Prime gets locally. Overall, let's just say, that we aren't expecting a lot of rebate money from gas purchases this year on our COSTCO card. That might be the only downside.

Oh, last July, just as my car came in, I went through the entire house and replaced every CFL light bulb with LEDs. That helped to close the gap on the electric bill quite a bit.

 

Is it economical to do much for a little saving on electricity bill?

 

You mean the LED bulbs? If so, it was time to convert over to those anyway. I was able to buy a bunch for about 77 cents each.

 

It mostly depends on how much the bulb is used, but it does not take a lot for it to be a no brainer to replace an incandescent with an LED.

Simple math tells you that a 100 watt incandescent bulb costs ~ 1.2 cents an hour in the country on average and perhaps 2 cents an hour in CA. A good LED uses about 10% of the power of an incandescent for the same lumen output -- so the incandescent cost 1 -2 cents an hour more. In 50 - 100 hours of use you have paid for the bulb. The arithmetic for a 60 watt incandescent bulb replacement works out to ~ 50% more hours until paid off, so 75 - 150 hours of use.

We have lights in the house that are used 2 - 5 hours a day.

 

I see that’s a lot of saving

 

It adds up over time, and you pollute less.

This publication says that an average CA household consumes around 1,500 kWh a year on lighting, or about $300 a year. LEDs drop that charge to $30 a year

 

In my case I charge at home utilizing my excess solar so I have no cost. With net metering all is get is credit and I have a huge credit with the power company.
At work I charge from free if possible 4 days a week.
So I change twice one day a week twice and weekends. Cost of $0.155 per kWh. if I charge at my cottage. 6.3 kWh * 0.115 X 2 = $1.95 per week.

Almost free!

 

No doubt about it -- PV + EV is greeaat

In my household we drive about 16k miles a year, of which 10k are EV and 6k are petrol at ~ 60 mpg. We spend about $230 a year on the petrol and $50 on the PV supplied EV miles (amortized PV cost.)

 

Hi everyone, purchased a new 2020 prime within the past week, and now I'm trying to calculate rough #s based on this formula. My biggest question is, what should I be using for my electric charge cost? .042? .036? or a combination of multiple? Attached is a snip from my electric bill. Also, I was under the impression there's a discount if you charge off hours, if that's true, where would I find that?

Gas is $2.70 per gallon in my area, and I'm planning just to use 52/23 and 56/28 as average rough #s for now.