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How much am I paying to charge my car? Is this accurate?

Singhman

Member
Jan 18, 2021
28
14
Vancouver
I am new to the whole electric charging world, and was hoping someone could answer a simple question. When I look at the usage information on my car (swipe left from the tire pressure tab) , it says I drove 1,400km and used 227kw..

Now, my electricity provider charges around $0.10/kw...so to calculate how much I paid to charge my car for the first 1400km would be 227km x 0.10 = $22.70 for 1400km...

Is this accurate? Anything I'm missing here? Thanks in advance.
 

Sidekick

Member
Feb 26, 2021
12
14
Victoria, BC
Most/all of that will be at step 2, which is at a higher rate (0.14/kwh). 30% sounds too high to me (but I'm new to this as well)...maybe 10% for charging losses and pre-heat.

227kWh x 1.1 x 0.14 = $35.

BC Hydro has partial rebates for energy monitors which could help you track this more easily, or, you could get a gadget to measure the power draw from the circuit powering your charger.
 

Watts_Up

Active Member
Mar 4, 2019
3,120
2,076
In a galaxy far, far away
I am new to the whole electric charging world, and was hoping someone could answer a simple question. When I look at the usage information on my car (swipe left from the tire pressure tab) , it says I drove 1,400km and used 227kw..

Now, my electricity provider charges around $0.10/kw...so to calculate how much I paid to charge my car for the first 1400km would be 227km x 0.10 = $22.70 for 1400km...

Is this accurate? Anything I'm missing here? Thanks in advance.
About your electricity bill, do you have a ToU (Time of Use) with discount rate during Off Peak hours?
If so, your electricity bill should provide consumption for Peak and Off Peak.
Also, some electricity companies might provide a month/day/hour graph consumption on your account web site.

I would also recommend adding a Wattmeter connected to your charging plug at home, so you could monitor your usage
and know exactly how many kWh you used to charge your car.

I noticed a loss of about 8 to 10% when charging at home between the Wattmeter delivery value and the Tesla charging added value.
 

drtimhill

Active Member
Apr 25, 2019
1,616
1,937
Seattle
What do you mean?

You said your usage was 227kW, but that cannot be correct, since "kW" (kilowatt) is a measure of power, not energy. Power is defined as energy consumption per unit of time, where 1 watt of power equals one joule of energy consumed per second. So an 60W light bulb uses 60 joules of energy for each second its turned on.

The (rather odd) unit called "kWh" or "kilowatt-hour", is actually a measure of energy not power, and is defined as the amount of energy you use when consuming 1 kW of power for one hour. It is thus equal to 1000 x 60 x 60 joules of energy, or 3.6 MJ (mega joules). For some reason, power companies bill you in kWh units of energy instead of joules (the official SI unit of energy), and EVs have picked up on this.
 

jcanoe

Active Member
Oct 2, 2020
1,579
1,603
Maryland
I am new to the whole electric charging world, and was hoping someone could answer a simple question. When I look at the usage information on my car (swipe left from the tire pressure tab) , it says I drove 1,400km and used 227kw..

Now, my electricity provider charges around $0.10/kw...so to calculate how much I paid to charge my car for the first 1400km would be 227km x 0.10 = $22.70 for 1400km...

Is this accurate? Anything I'm missing here? Thanks in advance.
The usage tab information is useful for gauging your driving efficiency. It shows you used 227kWh to drive 1400km. It does not consider cost since this will vary whether you charge at peak times, off peak times , at work, at a free public charger or using a solar array.

The usage display does not factor in any kWh used for preconditioning before driving or if you leave the climate control running while you are parked and run a quick errand.

If you are charging at 240V then a good estimate of the overhead losses due to heating of the wiring, the battery and the onboard charger losses is ~10%. I.e., you will use 11kWh of electricity for every 10kWh that actually goes into the battery.

To determine your actual usage, cost of home charging you would need at home charging equipment that tracks usage or a smart meter. Straight up your Wh/km number is 227kWh/1400km or 162Wh/km. (I think in terms of Wh/mile; this is 259Wh/mi, a very respectable efficiency number especially in late winter.)

Without know whether you regularly precondition your Tesla vehicle before driving it is impossible to know your total kWh usage for charging and preconditioning and just sitting in the Tesla with the climate control running. I would conservatively add 40% additional kWh usage to account for overhead losses and for these activities. Even accounting for the additional 40% for preconditioning, your cost is approximately $0.0225/km ($0.036/mile.)
 
  • Informative
Reactions: srlawren

mark95476

Member
Jun 21, 2020
918
484
Bay Area CA
Just a comment:

I used to spent at least $150/month on gas just getting around. I've had my Tesla for ~8 months and it's been almost 2 months since my last out-of-pocket charging expense. $3.84 is equivalent to a gallon gas in the Bay Area right now. :cool:

LG_Supercharger.jpg
 

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