Getting used to miles/kWh

[Snagglefoot]

We all know what a good mpg rating is and what a crappy one is.

How about miles per kWh ( small k,capital W, small h) in electric vehicles? A gallon container is so much easier to visualize than a kWh.

So what’s a good rating in a miles per kWh? Although it’s highly dependant on acceleration, normal driving in a Tesla 3 might get you about 4 miles per kWh on the highway. On the other hand, driving an electric Silverado might get you 2 miles per kWh. Note sure if the EPA puts out standards on this yet. Feel free to fill in the details and get a discussion going.

 

[Snagglefoot]

I see the EPA has MPGe, which is the miles per gallon equivalent. The equivalent energy in one gallon of gas is 33.7 kWh. However, as people get used to seeing the display on the charger it may come down to simply how many kWh did they purchase, rather than how many gallons equivalent did they buy.

 

[Burt]

The other adjustment is we’re used to getting better mpg on the highway than in town (at least non-hybrid). Not so in EVs.

So a 300 mile quoted range is misleading. Who drives 300 miles in a day and never leaves town?

 

[Number_35]

I think one's perception of good EV mileage will vary with the relative cost of gasoline and electricity.

For example, a car here might average 10 l/100 km (c. 28 MPG Imperial/23 MPG US). At $1.30/litre, fuel cost would be $13 for 100 km.

$13 would buy 130 kWh of electricity (if one charges at home).

So, to break even on fuel cost, the car would have to use no more than 130 kWh/100 km - that is, travel 100 km on 130 kWh. That works out to about 62 miles on 130 kWh, so the breakeven point on fuel cost would be about 0.5 miles/kWh.

So, the fuel cost of running the Silverado EV, at 2 miles/kWh, would be 1/4 that of the ICE car, and the Tesla, twice as good as that, or 1/8 the cost of the ICE car.

So, I would consider 2 miles/kWh to be good.

However, refueling at a charging station would wipe out much, or perhaps all, of the savings.

The numbers work well here in favour of EVs because we have cheap electricity and expensive gasoline. YMMV!

 

[Astro_Guy]

We all know what a good mpg rating is and what a crappy one is.

How about miles per kWh ( small k,capital W, small h) in electric vehicles? A gallon container is so much easier to visualize than a kWh.

So what’s a good rating in a miles per kWh? Although it’s highly dependant on acceleration, normal driving in a Tesla 3 might get you about 4 miles per kWh on the highway. On the other hand, driving an electric Silverado might get you 2 miles per kWh. Note sure if the EPA puts out standards on this yet. Feel free to fill in the details and get a discussion going.

Speaking from personal experience with a small PHEV, a figure north of 3 miles per kWh is easily achievable for normal driving about town. Taking the same vehicle out on the highway at 70 MPH pushes that figure closer to 2 miles per kWh. Earlier this week I managed to deplete a full 7.2 kWh charge within 16 miles of high speed driving.

 

[Snagglefoot]

The other adjustment is we’re used to getting better mpg on the highway than in town (at least non-hybrid). Not so in EVs.

So a 300 mile quoted range is misleading. Who drives 300 miles in a day and never leaves town?

Yes, the fact that it can achieve more miles in the city than the highway is well proven and reproducible in the lab. There are many papers on this. I guess one could drive their route each day and if it’s short enough would only charge up when the energy was way down.

 

[Snagglefoot]

So one other consideration is how large is the “ tank”? A rear wheel powered Tesla 3 can store 57.5 kWh. The Performance model can hold 75 kWh. The Silverado EV can be configured to hold 205 kWh. These are numbers EV owners will get used to.

 

[Cujet]

A beer can. That's what a kWh is, as a general comparison.

About how far 12 ounces of fuel will push a conventional Corolla down the road with me driving it.

 

[macarose]

I'll just leave this here and keep listening to the ignorance brigade about how EVs cost so much money to keep running

Our average cost per kWh here in northwest metro-Atlanta is usually between 6.2 to 7.5 cents. With two hours of free charging nearby, our net cost is really just around a penny a mile

 

[Torrid]

I'll just leave this here and keep listening to the ignorance brigade about how EVs cost so much money to keep running

Our average cost per kWh here in northwest metro-Atlanta is usually between 6.2 to 7.5 cents. With two hours of free charging nearby, our net cost is really just around a penny a mile

View attachment 243318

That's impressive. Ours is about 3 cents a mile for the Model 3 and 8 cents a mile for the GTi.

 

[IndyIan]

I guess with EV's its useful to know the Miles/kWh and 60% of the kWh in the battery, as you probably only want to use the 80% to 20% range for the state of charge regularly.

Our cars average out to about 11-12 cents per km for gas with current prices at $1.4/L CDN.

We pay about 20 cents/kWh at home. 720kWh/month for $140
For us, in our climate I'll guess an average car EV might average 3-4 km/kWh, after charging inefficiency, cold weather battery heating, cold weather car heating, sitting around battery loses, etc, are accounted for.
So I guess we are at about 5-7 cents per km for EV fueling. So we would save about $1200-1300/year per EV.

A 5 year old used model 3 AWD is about $25k, so the fuel savings would save us a little more than the interest on a 5 year car loan. Then I've got a paid for, 10yr old tesla, in rural Ontario... Maybe a PITA to repair? I don't know, nearest dealer is 100km away.

 

[Snagglefoot]

I see the EPA has MPGe, which is the miles per gallon equivalent. The equivalent energy in one gallon of gas is 33.7 kWh. However, as people get used to seeing the display on the charger it may come down to simply how many kWh did they purchase, rather than how many gallons equivalent did they buy.

One US gallon is 128 US oz, so if one gallon of gas has the equivalent energy of 33.7 kWh, one kWh is equivalent to 128/33.7 = 3.8 oz of gasoline, so about 3 kWh in one beer can full of gas.

 

[PandaBear]

There are many ways to visualize energy: gallon of gas, kwh, calories (or kCal), therm (of natural gas?), joules, etc. Reason to use energy unit instead of mile is good because they don't change depending on temperature or how fast you drive, the problem though is you don't know how far you can go.

% of charge is to me good enough, and kwh is good if I need to keep track of how much to pay at the charger but not that big of a deal if I charge at home. I don't see the point of mpge unless you are trying to see whether you want to buy the car or not, or if you have a plug in hybrid and see whether you should go pump gas or plug it in.

The biggest cost of an EV is the battery depreciation over time. You probably should realistically expect 15 years of useful life before you either have to replace the car (sell it to someone driving it only locally), or replace the pack (will you use your EV for 30 years to justify the cost of a new battery?). Once you spread that out over the years and how many miles you drive over the years, it can dramatically tip the scale over to gas car's favor if you don't drive enough miles, or if you drive too much and you have to use the charging network or factor in the time wasted on road trips. My guess is the sweet spot would be 1 EV per family and people driving 20-100 miles a day, and have a hybrid for road trip.

 

[Torrid]

There are many ways to visualize energy: gallon of gas, kwh, calories (or kCal), therm (of natural gas?), joules, etc. Reason to use energy unit instead of mile is good because they don't change depending on temperature or how fast you drive, the problem though is you don't know how far you can go.

% of charge is to me good enough, and kwh is good if I need to keep track of how much to pay at the charger but not that big of a deal if I charge at home. I don't see the point of mpge unless you are trying to see whether you want to buy the car or not, or if you have a plug in hybrid and see whether you should go pump gas or plug it in.

The biggest cost of an EV is the battery depreciation over time. You probably should realistically expect 15 years of useful life before you either have to replace the car (sell it to someone driving it only locally), or replace the pack (will you use your EV for 30 years to justify the cost of a new battery?). Once you spread that out over the years and how many miles you drive over the years, it can dramatically tip the scale over to gas car's favor if you don't drive enough miles, or if you drive too much and you have to use the charging network or factor in the time wasted on road trips. My guess is the sweet spot would be 1 EV per family and people driving 20-100 miles a day, and have a hybrid for road trip.

I really think the MPGe calculation is only there for CAFE standards. Because of that it gets printed on every EV window sticker and it really doesn't mean anything to anyone other than figuring out CAFE. I do like efficiency for the sake of using the least amount of energy possible to get from A to B(when I'm not trying to make a squiggly fun line between those points). I'm not as concerned with it with EVs just because of the cost of electricity, it will be cheaper to operate than any ICE vehicle for me. I'm also not used to it in daily driving yet. When I do buy an EV for my daily drive then it will click and make sense. That said, I do really pay attention to fuel economy when it comes to commuting. I don't have a short drive and it's also a good indication of a mechanical issue if a drastic change happens out of nowhere.

 

[OVERKILL]

I guess with EV's its useful to know the Miles/kWh and 60% of the kWh in the battery, as you probably only want to use the 80% to 20% range for the state of charge regularly.

Our cars average out to about 11-12 cents per km for gas with current prices at $1.4/L CDN.

We pay about 20 cents/kWh at home. 720kWh/month for $140
For us, in our climate I'll guess an average car EV might average 3-4 km/kWh, after charging inefficiency, cold weather battery heating, cold weather car heating, sitting around battery loses, etc, are accounted for.
So I guess we are at about 5-7 cents per km for EV fueling. So we would save about $1200-1300/year per EV.

A 5 year old used model 3 AWD is about $25k, so the fuel savings would save us a little more than the interest on a 5 year car loan. Then I've got a paid for, 10yr old tesla, in rural Ontario... Maybe a PITA to repair? I don't know, nearest dealer is 100km away.

You guys in the country get boned on delivery, I pay ~$0.145/kWh in town and that's all-in, taxes, delivery...etc.