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# Am I calculating my total cost correctly?

porkisking 11 months ago updated by Pstreicher 10 months ago

So I'm trying to calculate how much my model Y is costing in electricity and my math is telling me it's much more than advertised. So here in NJ, according to my last PSE&G bill, my electric supply costs is .13 per kWh and my electric delivery costs is .05 per kWh. So total is .18 kWh. My odometer is now 5483 miles. According to TeslaFi, which I've been using since the beginning, I've used 2389 kWh which costed me \$431. Comparing to a fossil car,  \$431 would buy me about 172 gallons of gas @ \$2.50/gal. 5483 miles / 172 gallons gives me only 31 miles per gallon. Even if I assume perfect 100% charge efficiency and use 1970 kWh for the math, it would have cost \$355 instead. That buys me 142 gallons and still gives me only 38 mpg.

Why is my Model Y as efficient as a gas powered Toyota Corolla? Is my math wrong somewhere?  I would check in the settings here at TeslaFi and make sure the power cost is set correctly at .18 per kwh to start.

Dividing \$260.54 by 5348.18 = .0487. To me that don't look right. It should equal .18 in my book.

I am a newbie too and have been trying to understand my electric costs also. I did buy an energy meter on eBay and it shows almost exactly what TeslaFi is showing for energy used per charge. Every time I look at this it is confusing. You have to do several different calculations various ways in order to understand what is what. Do this enough times and then it will come to you. I now have figured out that my old '99 Nissan Pathfinder at 16.5mpg was costing me four times as much in gas cost vs. electricity. Figuring it on my wife's 2010 Rav4 at 24mpg, that thing is costing three times as much. So, what I have come up with now is a fill up of electricity costs me around \$7.25 and the Rav4 would cost me around \$22. This amount to get me around 100 miles of driving. That was using the cost of gasoline at \$2.29 at the time. I hope I have shed some light on this for you.  Also if I look at my total drives it shows I've used 1423 kWh. Why this is so different than the 1970kWh above? Where did that additional 547kWh get used?

But even using 1423 kWh with a total cost of ~ \$260, that \$260 buys me 104 gallons of gas @ 2.50/gal. 5348 miles driven with 104 gallons of gas gives me 51 mpg but nowhere near the EPA 120 MPGe. Looking over your post again, Used is different than Added. Don't let this confuse you in your calculations. Added means just that. The charge added and used means, well, you have driven it. That's the way I understand it.