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How to calculate how much it cost to charge at home?

How to calculate how much it cost to charge at home?

Hi there,

I just picked up my Model 3 Standard Rage Plus this afternoon. I was wondering if there is anyway to figure out how much electricity it cost me for my first charge at home. The battery was at 50% and I topped it up to 80%. My off peak cost for the Hydro is 6.5 ($0.065) cents per kilowatt hour. I was able to get up to 51 km/hr with my Tesla Wall Charger, and it took approx 3 hours and 15 mins to get from 182 km to 343 km. How do I calculate what that cost? I thought it might be 75 KW battery * 30% (as I only charged 30% of the battery) = 22.5 KW * 0.065 = $1.46 to charge my car?

Am I close or way off?

Thanks

DrSteve | September 28, 2019

The simplest way to calculate costs is to take your Wh/mile (or Wh/km) measurement and multiply by your cost of electricity. This slightly underestimates the actual cost since there is some loss in the charging process. You can compensate for this by increasing the result by about 15%. The problem with using your wall charger time is that the actual charging rate slows down as the battery fills. Here is the calculation I did for my M3.

I have been averaging 0.27kW/mi in Model 3. I have a TOU electrical plan at home and during super-off-peak my electricity is $0.13/kWh. So that corresponds to 3.5c/mi. Compare this to my wife's Prius which gets around 45mi/gal and gas at $4.00/gal. This corresponds to 8.8c/mi. So my Tesla fuel cost is around 2.5x lower.

Kary993 | September 28, 2019

San Diego TOU 0.09 cents a kWh -> 0.09 * 75 if completely empty $6.75 for 310 miles. Yes some loss but hey a lot of miles for cheap compared it gasoline!

FISHEV | September 28, 2019

You need to look at a pre-Tesla bill to see what your actual dollars/kWh are. Looking at the base rate doesn’t really tell you what you are paying per kWh as there are various fees and taxes and several voluntary programs such as paying more for sustainable power, dam removal etc.

I live in OR, one of the cheapest electric states in US but I have solar power so I get charged for a 2nd meter and a monthly fee along with taxes, fees, sustainable power, salmon recover, dam removal etc, My actual average price per kWh is $0.31. Tesla charges me $0.28 at the SC so cheaper to buy from Tesla than to charge at home. I can’t charge at home anyway but the numbers are interesting.

Kary993 | September 28, 2019

Thanks for over complicating this thread with crap FISHEV.....

FISHEV | September 28, 2019

Yeah...reality bites but figuring out your actual cost per kWh is always a good thing to do.

jdcollins5 | September 28, 2019

@paulsurette71 - Sorry no one really answered your question. Yes your estimate is close enough.

BRosie | September 28, 2019

@paulsurette71 - Your calculations are correct, but I believe the LR+ has a 62kWh battery. So that (62×30%)×0.065 = $1.21

Rodo | September 28, 2019

Really! $0.065/kWh, is that Canada? I pay US $0.19/kWh in Southern California. I think of about 8kWh (kilowatt per hour) for me when I charge. That covers the car plus whatever I'm using for that hour. I can't run much of anything else (high power) in my condo while I charge (TVs and computers are fine). I think it is ~7.7kWh for the mobile charger (240v x 32A = 7680 Wh ~= 7.7kWh) then you can figure the money per hour (7.7 x 0.065 = $0.50 ) and quickly multiply how many hours you charged. Hope that helps.

whazupman | September 28, 2019

Georgia TOU from 2300-0700 is $0.014164 kWh = Nearly FREE!!!

My two M3's cost almost nothing to drive :)

cussenjim | September 28, 2019

I am envious, pay about 12 cents per kw/h in Texas, day and night. Still about 1/3 the cost of the boxster gas, I traded in for the 3.

Frank99 | September 28, 2019

paulsurette71 -
Yes, you're pretty close. No need to overcomplicate things unless you really want to.

If you want to overcomplicate things, you'll need to get the tariffs (rate documents) from your electric utility to understand how much of each tax and fee on your bill is assigned to on-peak, off-peak, or fixed. A spreadsheet really helps out. Then you can calculate how much each kWh is actually costing you (my off-peak rate is about $0.044 / kWh, but after adding tax, license, and dealer prep, my actual cost is closer to $0.066 / kWh). But, off-peak, I calculate the same as you - 75 kWh * $0.066 / kWh = $4.95 for a 0-100% charge and 310 miles of range. Add perhaps 10% to that for various inefficiencies in the charging process, and you're probably remarkably close to the "truth".

andy | September 29, 2019

Do you have smart meters in the US? These give a display of usage and cost in real time and historical. I charge between 0:30 and 4:30 AM as that’s the time I can get electricity for 5p a unit. Very little else is running at that time and it’s easy to just take a point cost for an hour or compare with an hour on a day when there was enough charging.

Hal Fisher | September 29, 2019

I think a standard range is 62kwh. So 30% of that is 18.6 x .06 plus loss, yeah about $1.15 to 1.20.

Hal Fisher | September 29, 2019

Realize tire wear is about a penny per tire so 4 cents and electric is about 2.3 cents a mile. Bet you never thought there would be a day you pay more in tire wear than propellant hahahahaha!!!

andy | September 29, 2019

Love the comment above on tyre wear. Wish we had a “like” button.

rob | September 29, 2019

@OP

The "Stats" app for Tesla is a great app and it can calculate the costs of you charges. I highly recommend it.

wb808 | September 29, 2019

In Hawaii we have the pleasure of paying $0.36/kWh, so those of you jealous of low electric rates rest assured you got it good compared to here haha!

That definitely does eat into the feeling of running this car on the cheap though, as using my lifetime average 240wh/mi gives me an 8.6 cents/mi fuel cost. Extrapolating from there at $4.00/gal of gas would put this car’s mpg fuel *cost* equivalent of about 46mpg. However that’s still pretty damn good when considering the performance of this car even when using ridiculously high electric rates!

Patrick | September 29, 2019

Here’s an option if you REALLY want to know your charging energy use and cost:

https://forums.tesla.com/forum/forums/tesla-fuelenergy-manager

Ours works out to about $0.018 per mile verified using this method.

Taffy | September 29, 2019

Could someonew pleas tell me how to start a new thread on this forum?

spiderx1 | September 29, 2019

Stats App does this for you, plus put in fuel cost and electricity cost and it also calculates savings. Georgia EMC gives you a 28$ credit on your bill if you register with them, requires proof of purchase of EV.

jfaubl | September 29, 2019

I run a monthly odometer on the car. I look up how much energy it used. I had teslafi for a bit and it said I was 94% efficient charging.
So let's say I used 100 kWh. That is 94% of 106.38. I then look at my total electric bill. Say it's 300 kWh. 106.38/300 and multiply by my total bill. Pretty close estimate with my tax and delivery charges.
I do have cheaper costs overnight so the actual cost is as bit lower but it amazes me how much of my electric bill is taxes and delivery charges.

jfaubl | September 29, 2019

OMG. I just read everyone's rates. Comed in northern IL overnight is usually 1-2 cents kWh. Sometimes it is negative so I earn money charging. usually -1 to -2 cents but last night was -6 for a few minutes.

rsm3 | September 29, 2019

I am just starting to research this myself, came across Sense - https://sense.com/, anybody using it?

kevin_rf | September 29, 2019

My TOU rate is 1.5 cents per kwh. That does not include delivery and other surcharges. When you factor them in, mine works out to about 9.5 cents per kwh. For me, it's easy since the car has it's own meter, the house usually works out to ~18 cents per kwh.

It would be very interesting to see how the OP's bill breaks down with fees and surcharges. Kinda curious how they do that in Canada.

Some US electric bills are almost as incompressible as a cell phone bill.

N8778204151 | September 29, 2019

In Anaheim CA,
0.1975/kwh

Atoms | September 29, 2019

At $0.065/kwh, your cost should be about 1/5 what you would pay for driving a Honda Accord.

mcmoyer | September 30, 2019

man...those are some outrageous rates. I got lucky and am on one of those free nights programs so from 8pm to 8am, that's my charging window

mcmoyer | September 30, 2019

man...those are some outrageous rates. I got lucky and am on one of those free nights programs so from 8pm to 8am, that's my charging window

slingshot18 | September 30, 2019

Be cautious about night time rates and how your utility generates that electricity. It may cost more, but if you charge during the day when solar is a bigger contributor, you’ll be doing the environment good. And it’s still dirt cheap.

Brunoranger | October 1, 2019

Seems close but you also have to know that the wh/mi shown on the car is only the effectiveness of your driving. This doesn’t include any loss from vampire drain, sentry mode, cabin overheat, dog mode, idle, etc etc. plus you have charging loss from outlet to car.

Safe bet I guess is 20-25% (depending on how much you use sentry mode etc) over what the car says your consumption is.

I went crazy over calculating exactly how much the Tesla would cost me compared to my gas car in the beginning before buying it and the first month or two. Now I just drive it and don’t care.

My electric probably went up $120-130 a month on average but I drive 2000 miles a month. It was about $190-200 a month for gas, so, hence a savings.

bjrosen | October 1, 2019

Don't use Sentry mode at home unless you live in a terrible neighborhood, the vampire drain from Sentry mode is awful but if you don't use it then vampire drain is negligible, a mile or two a day which is only 50-100Whs. If you want to know the total power you've used while driving don't ever reset Trip B, that way you will have a complete accounting of your lifetime usage. To get your cost per KW just look at the bottom line of your electric bill and divide by the number of KWhs than add about 10% to account for charging losses.

bpaul | October 1, 2019

Fishev and bjrosen have suggested dividing your bottom-line bill dollars by kWh. That's not ever going to be the right answer for what the OP is asking. OP, you're doing it right, but you might also look for other *per-kWh* charges suggested by others, including taxes and losses, and and them to your $.065/kWh.

On the assumption that everybody here had electricity service before buying their first EV, the fixed charge(s) (aka "customer charges") shouldn't be allocated to your Tesla driving because you would be paying them even if you didn't have your Tesla(s).

andy.connor.e | October 1, 2019

You would be paying them whether you used electricity or not. When i dont use my house AC, half my utility bill is fixed charges for being hooked up to the service, the other half is what i actually used split between being charged for supply and delivery. You also need to account for losses which occur before entering the car which is probably only a few percent. My suggestion is now that you have an electric car, highly consider getting solar panels.

hokiegir1 | October 1, 2019

I use TeslaFi, and we recently installed a meter on our charger, just to see how close the usage estimates were. Over the course of a month, TeslaFi's reported usage that includes loss estimates was +/-2kwh from the meter's report for the month. If you want reasonably accurate data without a lot of work, I suggest giving TeslaFi a shot. They have a free trial period, as well.

Effopec | October 1, 2019

Your simple calculation is close enough for most purposes. The charger is only about 90% efficient, so it would probably be closer to divide your answer by 0.9.

St☰v☰ | October 1, 2019

@Rodo | September 28, 2019
Really! $0.065/kWh, is that Canada? I pay US $0.19/kWh in Southern California.
______________________________________________________________________

Wow, I'm paying $0.12/kwh in South OC. Is that a TOU rate?

Spif | October 1, 2019

I'm at 11 cents/kWh from my bill. That includes all per-kWh charges and taxes, but does not include any fixed costs.

That translates into roughly 3 cents/mile in the summer (220-250 Wh/mile) and 4 cents/mile (About 320-350 Wh/mile) in the very cold months, including a .9 efficiency conversion.

It's a fairly large difference between warm and cold weather, but I end up heating up my cabin 3x per day in winter, for relatively short drives (< 10 miles). At least it overnights in an attached garage (40-50F)

derotam | October 1, 2019

@Taffy, scroll ALL THE WAY to the TOP of the page to where it says TESLA, Model S, Model 3, Model X... and then look just below that.

kevin_rf | October 1, 2019

It all depends on the line items on the bill. Some are fixed, some are proportional to the number of KWh's consumed. Really curious what line items OP has in Canada.

With the exception of "Customer Charge", which is fixed at $4 per meter, all of mine are proportional.

For giggles from my last bill

Car meter:

Customer Charge: $4.00
Energy 586 KWh @$0.012: $7.03
Distribution 586 KWh @$0.0553: $32.41
PPA Charge (An adjustment between predicted and actual KWh cost to Utility): -$2.93
Transmission Charge (Delivery charge between plants and our power company): $8.15
Total: $48.66
So this month, ~8.3 cents a KWh, last time I calculated it, it was 9.5 cents.

House Meter:
Customer Charge: $4.00
Energy 374 KWh @$0.072: $26.93
Distribution 374 KWh @$0.0665: $24.87
PPA Charge (An adjustment between predicted and actual KWh cost to Utility): -$1.87
Transmission Charge (Delivery charge between plants and our power company): $5.20
PASNY Credit (Something to NY generated hydro power offsetting New England costs): -$4.56
Total: $54.57
So this month 14.6 cents a KWh. Again it will vary...
*it was 374 KWh after solar generation is removed for the month.

Notice, everything is actually variable, except the meter cost. I am curious why the car bill lacks a PASNY credit. Might because it has a TOU plan?

You need to figure out, which lines are variable when calculating your true costs. It is possible some of the surcharges and credits are actually based on time of day usage and they do not note it on the bill.

jrweiss98020 | October 1, 2019

Rough, simple back-of-the-envelope calculation for LR-AWD:

310 mi range / 75 KWh battery = 4 mi/KWh.
Local electric rate ~10¢/KWh
Cost = 2.5¢/mi

Making it a bit more complicated for comparison, at a typical $3/gal for gas and 30 mpg on my old 2010 Lexus hybrid, cost was ~10¢/mi.

Now I just found out WA is raising the yearly car tab surcharge for EVs from $150 to $225, and adding a $75 surcharge for hybrids (plug-in or not)...

FISHEV | October 1, 2019

"Fishev and bjrosen have suggested dividing your bottom-line bill dollars by kWh. That's not ever going to be the right answer for what the OP is asking"@bpaul

Actually its the only accurate way to know what you paid per kW into the car. Looking at a single line for rate leaves out a lot of the costs on the bill.

It's nice to know what it costs but it's a bit of a red herring as the reason for EV's is no emissions. if it cost more to charge I'd still do it as the best way to cut travel emissions.

With right wing politicians trying to tax EV's, one could see a scenario where they have the public utility commission require the utilities to charge more for EV charging to the point of trying to recover "lost" gasoline tax revenue. So there's no promise going forward that EV's will be cheaper. I only save $750 a year based on all SC charging vs. $3.50 gasoline. Money for the boat fund but not a game changer or the real reason to buy an EV.

TM3Q | October 1, 2019

I was reading all your comments avout how to calculate your electric fees....

You got a smart car and it even tells you how much you put in.....just do this math:

Voltage shown while charging, example 240V
Amperage going in your car 48A

240V multiply by 48A equals 11.52 kW real comsuption

Now you only need to know how long it charges at that rate and multiply by $/kWh

After reaching a certain % your amperage will start to drop so you need to adjust your calculation.

Don't forget even of you have a 75kW battery it doesn't mean you car will use exactly that wattage to recharge, there's other power comsuption like battery heating, ventilation, etc.

That's why by monitoring your app while it recharge you can easily check your Voltage and Amperage at any moment, don't need to have any fancy sensor :-)

nivS1978 | February 24, 2020

This website do all the calculations for you. Select your care brand/model and what type of socket you connect to and the charge level (e.g. 50-90 %) and it will show you the time it takes.
https://evcompare.io/charging-calculator/

wiboater4 | February 24, 2020

Anyone know how much it costs to keep the battery at the proper Temperature when the car is parked and charging on a Tesla wall connector in cold and hot weather? For example if I'm not using my car for 5 day's and it's 20 degrees during that time it's using electricity for battery heating right.

h2ev | February 24, 2020

@TM3Q

I have a solar system with consumption monitor which provides accurate real time consumption data. I have the Gen1 40A mobile charger. Before I had the solar system in place, I too just assumed 240V x 40A = 9.6kW of draw while charging. In reality, it draws ~7.5kW on my typical charging routine (plug in at ~40% SOC and charge to 85%), which I'm guessing is due to a ~20% efficiency loss. Last week I took the car down to 15% and it was drawing 8kW when I plugged it in and quickly dropped back down to the usual 7.5kW. I've never taken my car below that so I don't know if it can ramp up a higher kW draw, but my guess is no.

It consumes roughly 25kWh when I charge it from ~50% to 85%.

Here's the graph from when I plugged the car in at 15% SOC. It only stayed at 8kW for about 15 minutes.

https://imgur.com/3UZX078