Is my math mathing

[thx10]

Tomorrow will be my one-week anniversary with my 2025 GT. And I am loving it.

Currently just charging with Level 1, works great but a little slow. Will be getting a Level 2 as soon as Ford dealer gets it in.

Anyway, I am trying to figure out my cost to "refuel".

The residential electric rate where I live is 13.31 cents per kWh. This would be the rate plus the demand charge per kWh. (.0590 + .0741 = .1331)

I live outside the city so I have to pay an extra 5% which makes it 13.98 cents per kWh

So I assume I take a recent charge of: 15KWh x $.13.98 = $2.10

link to rate sheet: pricing-electric-residential.pdf

Is this math right to be that simple to get the cost?

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[hybrid2bev]

Tomorrow will be my one-week anniversary with my 2025 GT. And I am loving it.

Currently just charging with Level 1, works great but a little slow. Will be getting a Level 2 as soon as Ford dealer gets it in.

Anyway, I am trying to figure out my cost to "refuel".

The (flat) residential electric rate where I live is 11.55 cents per kWh.

So I assume I take a recent charge of: 15KWh x $.1155 = $1.73

Is this math right to be that simple to get the cost?

Are you measuring the KwH coming from the wall or what’s reaching the battery? What is your source of the data?

Ford Pass only measures what reached the battery which is less than what the EVSE output due to charging losses.

 

[thx10]

Are you measuring the KwH coming from the wall or what’s reaching the battery? What is your source of the data?

Ford Pass only measures what reached the battery which is less than what the EVSE output due to charging losses.

I updated the rates, but i am using the kWh that is showing in my Ford app

how substantial is the loss? I assume not that substantial

 

[ChrisO]

I updated the rates, but i am using the kWh that is showing in my Ford app

how substantial is the loss? I assume not that substantial

I just found this power loss calculator, which seems pretty good for this use (even has the Mach-E in the pulldown menu):
https://powerloss.tech/calc/ev-charging

With 20A 10AWG wire, 120V, charging from 20% to 80% it says the loss is -0.4%.

Note that with being a 120V outlet it would be possible to put a "Watt o meter" on the line and get the actual power consumed (this would be a lot more difficult with 240V).

 

[GreaseMonkey]

Yes, math is that simple. But what are you trying to do with it? Generally people are looking for something more indicative than the total cost of a random charging session.

The most useful is cost per mile so you can compare to ice or something.

Soon enough you wouldn’t care about any of this and you’d just enjoy driving the car. This is my second Mach-E and next week I (and the wife) would have driven a Mach-E for three years straight (we share one car). The fun never subsides. Even my wife who doesn’t care about cars loves driving it.

 

[devmach-e]

I updated the rates, but i am using the kWh that is showing in my Ford app

how substantial is the loss? I assume not that substantial

Under Level 2, i’ll see “losses” of about 6% of what I drew from the wall versus what Ford Pass says. For instance, ChargePoint says I drew ~25.5 kWh, but FordPass says 24 kWh made it into the battery. 24/25.5 = 0.941.

Losses are higher under Level 1 because ancillary loads like cooling, fans, and electronics have to run for longer. I would add 15 to 20 percent to your figures. But your initial math is pretty good to start with.

 

[SpaceEVDriver]

This is about right, yes, though it’s not all that informative.

Don’t let people convince you that anything on the bill that’s not directly related to your electricity use (per kWh) should also be counted. If you’re paying a connection fee that’s not dependent on your energy or power draw, you’d be paying that even if you had an ICE.

The more informative cost would be based on a full charge from 0% to 100%.
91 kWh per 0%-100%.
Assuming 75% efficiency of the L1 charger

(91 kWh / 0.75%) * $0.1398 = $16.96 for 0-100%.

If you get 300 miles per charge, that’s 5.65 cents/mile.


If you have a rate plan with a variable cost, you could get significantly lower per-mile costs.
Our winter rate plan for super off-peak charging is 3.495 cents/kWh. And I get around 95% efficiency on my L2 charger (as measured by my CT devices). That gives me a 0%-100% fill up cost of $3.78.

We’ve mostly been driving the Mustang around town, so we get close to 4 miles/kWh = 350-364 miles per fill-up, sometimes more sometimes less.

$3.78/350 = 1.26 cents/mile.

 

[Teslaeata]

I have mileage & charge cost stats for 116,500 miles for tax reasons.

I use the kWh delivered from the wall (or the DCFC) multiplied by the cost/kWh, just like you’d use the cost of petrol/diesel delivered by the pump for an ICE car (litres/gals x $£ cost per), because that is the true cost to charge the car and includes the cost of the loss between wall & car which is realistic.

From that data you can accurately calculate the true and exact cost to you per mile and the miles per kWh you actually achieve which, again, I feel is realistic because any loss between wall/DCFC & car is a fuel cost and is power/fuel usage relative to the miles you drive the car.

………….is my view for what it’s worth.

 

[Teslaeata]

Speaking of stats, E&OE, my cost analysis at 115,876 miles were:

Total kWh from the wall/DCFC was 40,566.9kWh costing an average of 27p/kWh

618 home charges delivered 30,886.7 kWh @ ave cost of 15p/kWh

337 DCFC charges delivered 9,680 kWh @ ave cost of 67.4p/kWh

Ave power consumption was 2.856miles/kWh

Ave mileage cost was 0.986p/kWh

Actual fuel saving over ICE averaging 48mpg which is unrealistically high for the use to which I put the Stang is £5,250 so should probably be a higher figure in reality and would be £10,728.89 if I could have charged only at home though with days out starting at c300 miles is not possible.

 

[RickMachE]

Divide by .85 for 15% loss with level 1.
Make sure you include from your bill all variable costs, including tax.

Our utility advertises an off peak rate of a few pennies. It is really 16.5 cents.

FordPass may report inaccurate total kWh. Many threads on this. Verify by dividing by miles driven and ensuring miles per kWh is average, or % of battery charged times battery size.

 

[NorthlandPhil]

What @RickMachE said. Our power company (MN Power) lists per kWh charges and then adds a shit ton of other stuff -- state tax, county tax, city tax, city "Franchise Fee", "Fuel and Purchased Energy", "Low Income Affordability", etc. The taxes alone total 11.875%.

I've been putting this in spreadsheet for past 6 years because, well, I need a life, I guess. I also have Time Of Use rates so I charge 11pm to 5am when its the lowest.

In short, it's pretty much impossible to tell exactly what that last kWh that went into my car costs. But I try to average it out and add the "extras" to the per kWh charge and I come up with about $0.13/kWh total (on average).

They recently upped the per kWh charges, but then the extras dropped, and last month my bill was lower. I don't expect that to last...

You probably need to at least add taxes. I do like to have some idea of what my car (ICE or EV) costs to operate. But I don't get too hung up on it. I didn't but EV to save money, I bought it for the experience. And I'm very happy with it.

 

[ChrisO]

Divide by .85 for 15% loss with level 1.
Make sure you include from your bill all variable costs, including tax.

Our utility advertises an off peak rate of a few pennies. It is really 16.5 cents.

FordPass may report inaccurate total kWh. Many threads on this. Verify by dividing by miles driven and ensuring miles per kWh is average, or % of battery charged times battery size.

I imagine they are quoting the “generation cost”. On our PG&E bill “delivery cost” is about double the generation cost. Like you said you really need to check the bill to get the real cost.

A couple of things they do right though it put the right total cost in their graphs and in a CSV file that can be downloaded, broken out in hours.

 

[Triggerhappy007]

I imagine they are quoting the “generation cost”. On our PG&E bill “delivery cost” is about double the generation cost. Like you said you really need to check the bill to get the real cost.

A couple of things they do right though it put the right total cost in their graphs and in a CSV file that can be downloaded, broken out in hours.

I think that is their actual costs including taxes. CA and HI pay much higher rates than the rest of the US. Look at the averages here:

https://poweroutage.us/electricity-...production, keeping electricity prices stable.

I have TOU (345 kWh peak, 1765 kWh off peak) and pay 11.85 cents/kWh including taxes and fees. My bill was $250 for 2,110 kWh.

 

[ChrisO]

I think that is their actual costs including taxes. CA and HI pay much higher rates than the rest of the US. Look at the averages here:

https://poweroutage.us/electricity-rates#:~:text=Cheapest states for electricity States like Utah,,local energy production, keeping electricity prices stable.

I have TOU (345 kWh peak, 1765 kWh off peak) and pay 11.85 cents/kWh including taxes and fees. My bill was $250 for 2,110 kWh.

I was referring to the pennies to 16.5 cents statement. As in the utility advertises one amount but the true cost is more.

The way PG&E does it on their bill was just an example, of what might be the one reason for the two numbers.

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