Calculating cost of home charging

[Sawdusty]

I've seen people mention in various threads that it costs them $X to charge at home for the mileage they've put on their MME. I'm curious how to determine that.

I bought my MME late December 2023 so I haven't had it six months yet, and I've only ever charged it at home. I immediately had an electrician run a 50amp circuit to my garage and installed the charger that came with the car. I use the car for commuting to my job almost exclusively, plug it in Friday night, charge to 90%, and it's ready for another week. I've looked at my electric bill, comparing my overall KWh pre-charger to the last 5 months or so, but there's so much fluctuation in the overall KWh I use on a monthly basis depending on various factors- which or how many of my kids are in the house for any length of time, outdoor temperature, whether we've had house guests, etc.

How do people determine what it's costing them to charge their EV when charging it exclusively at home?

Sorry if there are other threads on this, I looked but not finding anything on point. Thanks.

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[thenew3]

It's easy with a smart charger, as it'll show how much power was delivered to the car. (not all of it is used to charge the battery). Some smart chargers can even tie to your utility account to get your rates (if you have different time of use rates) and calculate your cost for you.

Since you don't have that, you can look at the fordpass app, under charge history you should be able to see your previous charge sessions and roughly how many kwh or % you added.

So you just have to add those up and multiply by whatever your utility rate is to get what your total cost is for the month.

Here's an example of what a smart charger can show you.

 

[emichnov]

One way is to buy a better EV charger, one with an app that tracks your kWh usage. You can put in there what you pay per kWh for electricity, and it will calculate for you how much it costs. I like the ChargePoint Home Flex, but there are lots of good ones out there. Check with yoru local utility for possible discounts.

The charger that came with the car won't last forever with daily use. Lots of threads on this.

 

[AtomicInternet]

The Fordpass app shows kWh used in charge history, and mine is almost consistently 2 - 4 kWh per day.

Given I pay 12¢ per kWh, I can average it out to 3 kWh per day and use:

30 days * 3 kWh * 0.12 = $10.8 / month.

If you want to add up each kWh in your history you can get the exact amount

 

[zvez]

I've seen people mention in various threads that it costs them $X to charge at home for the mileage they've put on their MME. I'm curious how to determine that.

I bought my MME late December 2023 so I haven't had it six months yet, and I've only ever charged it at home. I immediately had an electrician run a 50amp circuit to my garage and installed the charger that came with the car. I use the car for commuting to my job almost exclusively, plug it in Friday night, charge to 90%, and it's ready for another week. I've looked at my electric bill, comparing my overall KWh pre-charger to the last 5 months or so, but there's so much fluctuation in the overall KWh I use on a monthly basis depending on various factors- which or how many of my kids are in the house for any length of time, outdoor temperature, whether we've had house guests, etc.

How do people determine what it's costing them to charge their EV when charging it exclusively at home?

Sorry if there are other threads on this, I looked but not finding anything on point. Thanks.

no tried and true way, some people just quote raw kwh price when determining it. Me, I take an average monthly electric INCLUDING the taxes, surcharges etc, and divide by the number of kwh for the month. So with all the fees added in my state flat rate kwh is 15 cents a kwh.

 

[azerik]

Long time back I figured out it's 3 cents a mile for me.
Emporia charger gives me a nice monthly recap and I usually run around $40 a month for the 2 EV's. Yeah I've got it much nicer than those in Cali for sure.

 

[zvez]

The Fordpass app shows kWh used in charge history, and mine is almost consistently 2 - 4 kWh per day.

Given I pay 12¢ per kWh, I can average it out to 3 kWh per day and use:

30 days * 3 kWh * 0.12 = $10.8 / month.

If you want to add up each kWh in your history you can get the exact amount

you know since the update the kwh delivered in fordpass on previous charging is wacky. Some bug in the way it calculates so for example, on May 25th my car added 118kwh!

Here's a screenshot of my charge history, keeping in mind 60% is about as low a SOC as my car ever gets.

 

[devmach-e]

no tried and true way, some people just quote raw kwh price when determining it. Me, I take an average monthly electric INCLUDING the taxes, surcharges etc, and divide by the number of kwh for the month. So with all the fees added in my state flat rate kwh is 15 cents a kwh.

This is the way...

And assume you get 2.7 miles per kWh.

 

[AtomicInternet]

Maybe mine is more consistent because of how few kWh I charge up with. Mine seems to be accurate after the app update (Android).

I'd recommend this for absolute certainty of how much you're using, but as mentioned might be better to just get a charger that reports kWh usage instead.

https://www.amazon.com/40-300V-Display-Multimeter-Multifunction-Frequency/dp/B0CCR13JL8/

 

[OWG]

How do people determine what it's costing them to charge their EV when charging it exclusively at home?

Sorry if there are other threads on this, I looked but not finding anything on point. Thanks.

How obsessive are you?

For me the most important is the fully loaded delivered cost of electricity (supply, transmission and other) My utility breaks it down by kWh.

Once you have the price per kWh then to consumption:
There are multiple points at which you can measure:
What goes into the car (FordPass data Post #7 zvez)
What comes out of the EVSE (Post #2 TheNew3)
What comes out of the panel.

I do not see a huge difference between what the EVSE reports and FordPass, but there is a difference (FordPass rounding?)
I see a ~10% loss between the panel and the EVSE.

I have a energy monitor in the garage panel How the Vue Energy Monitor Works - Emporia: Revolutionizing Home Energy (emporiaenergy.com)

 

[Teslaeata]

Only really accurate method is to meter the power used by the charge point.

If not smart meter your electrician could fit a simple metering device on the supply just to the charge point.

Then it’s just a matter of multiplying by price/kWh, divide by miles and, presto!

I got a spreadsheet with c87,000 miles and every kWh of charge power used in 3 years and so can run all sorts of analysis for various reasons.

Must’ve bought around 30,000kWh, around 75% at home the rest on DCFC.

 

[markboris]

Long time back I figured out it's 3 cents a mile for me.
Emporia charger gives me a nice monthly recap and I usually run around $40 a month for the 2 EV's. Yeah I've got it much nicer than those in Cali for sure.

Except if you’re charging only with solar in Cali like I do. ?

 

[devmach-e]

Except if you’re charging only with solar in Cali like I do. ?

If you charge at night, you aren't charging on solar. And I say this as someone who has solar on his roof in California and who charges at night. Instead, I'm offsetting my electricity costs with solar. I still use the "divide total bill amount by total number of kWh that utility claims I used" method to determine my cents per kWh rate. And by "total amount of kWh that utility claims I use" I mean the amount that the utility says I used after subtracting out any excess I may have sent to the grid.

 

[Snakebitten]

I don't know how less-than-perfect the Emporium EVSE is at reporting the KWH that it delivers to the car each charge session. But it can't be off enough to equal a couple of Tacos El Pastor per month. ?

Close enough.

So grateful to not be too OCD on such things.

 

[markboris]

If you charge at night, you aren't charging on solar. And I say this as someone who has solar on his roof in California and who charges at night. Instead, I'm offsetting my electricity costs with solar. I still use the "divide total bill amount by total number of kWh that utility claims I used" method to determine my cents per kWh rate. And by "total amount of kWh that utility claims I use" I mean the amount that the utility says I used after subtracting out any excess I may have sent to the grid.

I am charging ONLY on solar. I have an Emporia EV charger that is set to charge only on excess solar during the day. That is how I mainly charge, however if and when I need to charge at nighttime or rainy conditions, my 4 Powerwalls take over (they run the house anytime there is no solar) and since they are only charged from solar, my car only gets charged from solar. While I am connected to my utility company (PG&E), I rarely use energy from them. My yearly true-up was just a couple of months ago in April and I had a $1600 credit.

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