How much does it cost me to fully charge and drive my car?

[cornbinder89]

the conversion from120 volt to 360+ volt is not 100% efficient, so the numbers will never match.

 

[Stanton]

This thread sure went all over the place! Here's another datapoint culled from 3 day gig I did in December (collected from OVMS data).
I consumed 52.7 kW to drive 194 miles; I pay 13.7 cents/kWh for electricity.
So my Leaf cost a total of $7.26 (total) or ~4 cents/mile for the 3 days.
It would have cost me ~$31 (@$3.10/gallon) total had I driven my wife's ICE car instead...so my Leaf saved me another ~$25 for the gig.

 

[ctrowat]

the conversion from120 volt to 360+ volt is not 100% efficient, so the numbers will never match.

Of course, but a 34% loss still seems excessive. Something else is consuming a fair bit of power while it charges overnight. I’m not looking to launch an investigation here but just sharing that the numbers can actually be quite a bit different from what people are estimating.

 

[DaveinOlyWA]

That’s exactly how I have been working out my cost per km. I have a Kill-a-watt and charge exclusively at 120V so it’s easy enough to measure. Surprisingly though the numbers aren’t quite what I would expect. The car says we are doing about 4.5km/KWh, but measured at the plug it’s actually about 3.2. Also, running our 80% SOH battery down to 20% then charging to 100% is taking about 21KWh when I would expect it to be closer to 15-16 (24KWh pack x 0.8 for health x 0.8 for usage).

Now it is winter here and we have the studded tires on and almost exclusively do short trips using the climate control all the time so I’m not expecting to even get decent efficiency, but the mismatch in charge amount is a bit confusing. My measurements are an average over 1200km so that should be enough to average out any irregularities.

Charging efficiency is based on the speed of the charge because overhead usage from BMS, cooling system, etc take from that charge sooo

120 volt/12 amp; 75% efficient
240 volt/12 amp; 83%
240 volt/15 amp; 86%
240 volt/20 amp 90%
240 volt/27.5 amp 91%

440 volt DC; 95-98% (varies based on SOC)

ALL the above measurements verified by Kill a watt and utility grade meter inline with EVSE and averaged over several charging sessions

DC measurements used by parsing LEAF Spy Pro data logs

 

[fastbike]

My granny charger pulls 2 watts.
Yesterday I had it plugged in for 7 hours and it lifted the charge from 60% to 80% on my 62kWh Leaf. So 14kWh in and 12.4kWh capacity obtained. That looks like 88% efficiency. The actual cost to me was zero, as I used the power that I am unable to export from my solar system as I'm limited to 10kW export even though I have 15kW available.

Also in our country diesel and EV cars pay 7.6c / km when driven on public roads (Petrol has the equivalent charge applied at the pump).

 

[jc2024Leaf]

Charging efficiency is based on the speed of the charge because overhead usage from BMS, cooling system, etc take from that charge sooo

120 volt/12 amp; 75% efficient
240 volt/12 amp; 83%
240 volt/15 amp; 86%
240 volt/20 amp 90%
240 volt/27.5 amp 91%

I appreciate your passing on the above. I like to charge at lower rates, this is good info to have.

 

[cornbinder89]

I appreciate your passing on the above. I like to charge at lower rates, this is good info to have.

I do, but only because I don't want to charge to 100%, guessing the time needed is easier at lower rates.
If I get a EVSE that I can set the Kwh limit, then I would charge at the full capacity of the OBC.
In over a year of ownership I have yet to QC.

 

[jc2024Leaf]

I do, but only because I don't want to charge to 100%, guessing the time needed is easier at lower rates.
If I get a EVSE that I can set the Kwh limit, then I would charge at the full capacity of the OBC.
In over a year of ownership I have yet to QC.

The app for Grizzl-E EVSEs allows you to set the amount it delivers to the vehicle. I'm trying to convince my EVSE manufacturer to add the functionality. The table DaveinOlyWA provided might allow you to compensate for efficiency.

I created the following spreadsheet program to estimate charging time, but it also estimates amount. I might tweak it with the info DaveinOlyWA provided.

B4=B5/B3/B7
B5=B6*(B2%-B1%)

	A	B
1	Charge Remaining (%)	32
2	Desired SOC (%)	80
3	Charger Rate (A)	27.5
4	Set Charge Time (hrs)	4.36
5	Watt Hours to Charge (KWh)	28,800
6	Battery Size (KWh)	60,000
7	Voltage (V)	240

 

[DaveinOlyWA]

I appreciate your passing on the above. I like to charge at lower rates, this is good info to have.

Be advised in areas where electricity is spendy w/o TOU, the speed of the charge can be a significant cost consideration

 

[jc2024Leaf]

So my utility has the following:

Pepco offers a special time of use rate for residential plug-in vehicle drivers that applies to your entire home's electricity usage. This rate (R-PIV) offers potential cost savings to customers who can reduce energy use during peak hours or shift their energy use from peak to off-peak hours. Peak hours are Monday – Friday from 12:00 p.m. to 8 p.m. excluding holidays. All other hours are off-peak.
Which sounds good, but when you go on the plan, PEPCO significantly increases the peak rate



My wife works from home, so I have to run HVAC at reasonable temps during peak so I'm skeptical that this plan will save me any money. My commute is 200 miles a week, which would be fairly constant while the HVAC charges vary wildly. Another issue is www.mdelectricchoice.com says the rate I should use to comparison shop for electricity providers is 0.1246 which doesn't jive with the 0.10506 rate listed in the table, so I can't trust the numbers in the table.

 

[fastbike]

So my utility has the following:

Pepco offers a special time of use rate for residential plug-in vehicle drivers that applies to your entire home's electricity usage. This rate (R-PIV) offers potential cost savings to customers who can reduce energy use during peak hours or shift their energy use from peak to off-peak hours. Peak hours are Monday – Friday from 12:00 p.m. to 8 p.m. excluding holidays. All other hours are off-peak.
Which sounds good, but when you go on the plan, PEPCO significantly increases the peak rate



My wife works from home, so I have to run HVAC at rea

So my utility has the following:

Pepco offers a special time of use rate for residential plug-in vehicle drivers that applies to your entire home's electricity usage. This rate (R-PIV) offers potential cost savings to customers who can reduce energy use during peak hours or shift their energy use from peak to off-peak hours. Peak hours are Monday – Friday from 12:00 p.m. to 8 p.m. excluding holidays. All other hours are off-peak.
Which sounds good, but when you go on the plan, PEPCO significantly increases the peak rate

View attachment 6620

My wife works from home, so I have to run HVAC at reasonable temps during peak so I'm skeptical that this plan will save me any money. My commute is 200 miles a week, which would be fairly constant while the HVAC charges vary wildly.

I'd be looking at solar to offset the high peak usage /rates.

 

[indylmc]

Any way you look at it, 21 cents a kWh, holy smokes that is high. I'm paying .13 cents a kWh in the midwest (Indiana).

 

[frontrangeleaf]

Any way you look at it, 21 cents a kWh, holy smokes that is high. I'm paying .13 cents a kWh in the midwest (Indiana).

Folks in CA and HI spend a good bit more. Our overnight is 11 cents. Varies some by season. With solar, we basically never pay more than minimum.

 

[Dooglas]

And anyway that you look at it, jc2024Leaf's post of standard Pepco rates In Maryland (10.5 cents per kwh in winter and 9.4 cents per kwh in summer) are already about as inexpensive as anywhere in the US.

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[Ancient1]

Just be glad you don't live here in California! PG&E just lowered their rates slightly as of the first of the year, so our current charges are .48879 for peak time (4 pm to 9 pm daily), .47209 for part peak (3 pm to 4 pm daily) and also 9pm to 12am daily), and then (wait for it!) the special EV charging rate, otherwise known as off peak (12 am to 3 pm daily) of only .30339 per kWh. Aren't we lucky?