figuring out cost per mile

[nschuster]

i'm trying to figure out cost per mile, and having some trouble. i assume if i'm getting 4.4 miles per kwh (according to my dashboard), all i need is the marginal rate per kwh from my utility company (Dominion Power in Northern Virginia). a simple calculation, which would then allow me to compare cost per mile of my Leaf to cost per mile of a gasoline-powered car.

the problem is i cannot find out the marginal cost per kwh for offpeak (overnight charging) from my utility. i checked their rate filing with the state, and it is impossible to figure out (at least for me). all i can gather is the average cost per kwh, which i assume includes peak and nonpeak, but also includes all other service charges.

what i need is the marginal rate for using up one more kwh at offpeak times.

does anyone have any suggestions?

thanks!

 

[DaveinOlyWA]

the car only tells you what it takes from the battery which is less than that battery needs to provide that same amount of power.

you need a method to monitor power from the wall to have an accurate charge amount.

in my sig, i illustrate the differences between true cost of power (AMPK which is miles per KW measured in AC from utility) and what the car uses to get down the road (DMPK which is DC power from battery)

now how you monitor the charge can be a challenge. if you are using 120. a Kill a watt is cheap and easy to use and very accurate.

as for me, i put a meter inline with the charging circuit i used. its a fairly easy DIY job and parts can be had for $40

http://www.mynissanleaf.com/blog.php?u=291&b=92" onclick="window.open(this.href);return false;

as far as your rates, simply ask them for a rate schedule. the same information should be broken out on your bill as well. i believe its required for them to provide the information. if there is no breakdown, then it is possible you dont have TOU (time of use) and are only billed on quantity tiers

 

[Nekota]

i'm trying to figure out cost per mile, and having some trouble. i assume if i'm getting 4.4 miles per kwh (according to my dashboard), all i need is the marginal rate per kwh from my utility company (Dominion Power in Northern Virginia). a simple calculation, which would then allow me to compare cost per mile of my Leaf to cost per mile of a gasoline-powered car.

the problem is i cannot find out the marginal cost per kwh for offpeak (overnight charging) from my utility. i checked their rate filing with the state, and it is impossible to figure out (at least for me). all i can gather is the average cost per kwh, which i assume includes peak and nonpeak, but also includes all other service charges.

what i need is the marginal rate for using up one more kwh at offpeak times.

does anyone have any suggestions?

thanks!

According to their web page you have several tariffs available

http://www.dom.com/dominion-virginia-power/customer-service/rates-and-tariffs/index.jsp" onclick="window.open(this.href);return false;

Which rate plan are you on?

Rate Schedules

Schedule 1 - Basic Residential Rate

Schedule 1P - TOU (Closed)

Schedule 1S - Demand TOU

Schedule 1T - Energy TOU

Schedule 1W - Time-Controlled Storage Water Heating

Schedule DP-R - Residential Service (Experimental)

Schedule 1EV - Residential Service With Electric Vehicle Charging (Experimental)

Schedule EV - Residential Electric Vehicle Charging (Experimental)

I used Schedule EV which is for dedicated meter for Electric Vehicle and for 300KWhr the cents per kWhr values are
15.3 OnPeak
5.9 OffPeak
5.2 SuperOffPeak

The LEAF reports KWhr used from the battery but your cost is the KWhr from the AC wall outlet. If you use a timer for charging starting at 0100 (1AM) and charge to 80% (10 bars) you can get an accurate KWHr estimate by enabling email notifications of your charging which are accurate to 1 minute resolution. The AC power out from the EVSE is 3.85 KW so you can take the minutes of charging from 1AM to the message time, convert to hours (divide mins charging/60) and multiply by 3.85KW to get KWHr in. Dividing by your miles will give the Wall to Wheels KWHr per mile, then multiplying by your cost for superoffpeak of $0.052 you will get your $cost per mile Wall to Wheels. For example if you drive 30 miles and the charge time back to 80% takes 2 hrs (1AM to 3AM) then you will have a cost of $0.39 for 30 miles or 1.3 cents per mile.

 

[nschuster]

Thanks!

More complicated than I thought it would be!