Smaller motors: Could EV trucks trade power for touring range?

[T-Willy]

New and upcoming EV trucks have massive power but poor or marginal range for remote touring. That power may be needed for towing, but it's overkill for touring.

I wonder, for those of us who tour but don't tow, whether smaller motors could trade power for range given same batteries.

Engineers: Is it generally true that smaller, less powerful motors are more efficient, and would yield more range by consuming less electricity? Or, do electric motors consume similar electricity, determined by load, regardless of their size or potential power output?

 

[Bobu]

The number of electric motors and their type are more important for range than their size/power. But all three factors have an influence. With vehicles like the Audi e-tron or Porsche Taycan it‘s easy to compare the numbers for different motor configurations since they are widely published.
The difference between a two motors medium power configuration and a three motors high power configuration is about 25% less range for the high power version (with an identical driving style). If you use the higher power regularly for faster accelerations the difference in range will of course be much higher.

 

[rruff]

I wonder, for those of us who tour but don't tow, whether smaller motors could trade power for range given same batteries.

My impression is that the motors in common use are very efficient already, ~90%. So consumption is mainly dependent on demand. Air resistance, rolling resistance, and weight. And of course on how you drive. With lighter, smaller and more aero vehicles the efficiency (miles/KWhr) can be great. But if you add a load of batteries to also increase range, weight and size necessarily go up as well.

Greater range in mainstream vehicles isn't going to happen unless/until battery energy density improves substantially.

The best application for EV tech is tiny urban vehicles. If we want to drastically reduce CO emissions, energy consumption, and transportation costs, this is a no brainer. Keep ICEs for long range vehicles.

 

[T-Willy]

The difference between a two motors medium power configuration and a three motors high power configuration is about 25% less range for the high power version (with an identical driving style). If you use the higher power regularly for faster accelerations the difference in range will of course be much higher.

Interesting. This is what I’m getting at. Less power, more range. I care about range, not acceleration. Twenty-five percent is significant, and it makes one wonder how much more could be gained if power were optimized for range.

While I agree with the other post above — that the next big leap will necessarily come from battery efficiency (and that’s on its way) — I still worry that manufacturers’ quest for the-most-powerful-motor-bragging-rights may overlook the very practical question of how power can be optimized for (touring) range.

 

[rruff]

With vehicles like the Audi e-tron or Porsche Taycan it‘s easy to compare the numbers for different motor configurations since they are widely published.

If you can link to that data, I'd appreciate it.

 

[Bobu]

If you can link to that data, I'd appreciate it.

For example here:

Audi e-tron

Der Audi e-tron ist das erste vollelektrische Modell der Marke mit den Vier Ringen. Der sportliche SUV kombiniert den Raum und Komfort eines typischen Oberklasse-Automobils mit einer alltagstauglichen Reichweite, der den Fahrer mit dem elektrischen Allradantrieb in ein neues Zeitalter...

www.audi-mediacenter.com

Audi e-tron S

Audi setzt seine Elektro-Offensive konsequent fort – mit dem neuen Audi e-tron S (Stromverbrauch kombiniert in kWh/100 km: 28,4-26,8 (WLTP); 28,2 (NEFZ); CO2-Emissionen kombiniert in g/km: 0) und dem neuen Audi e-tron S Sportback (Stromverbrauch kombiniert in kWh/100 km: 28,1-26,4 (WLTP)...

www.audi-mediacenter.com

I hope to links work since they are leading to the German Audi page.

Here are the numbers for WLPT:
e-tron: 26.1-22.2 kWh/100km and range 369-440km
e-tron s: 28.4-26.1 kWh/100km and range 344-375km
They have the same battery, just the motor configuration is different.

My real world experience of the range difference is a bit higher than the above official numbers, probably due to my driving style being different than WLPT. That’s why I said around 25%.

 

[rruff]

I don't believe that is typical. If the only change was motor size (everything else the same) the difference would be tiny. Tesla Model S for instance... the Plaid high performance version with 1020hp and 3 motors has an EPA of 116 mpge, vs 120 (3%) for the dual motor 670hp version . The big effect on Teslas is if you have 21" wheels vs 19" (this is an option on the S Plaid)... guessing most of that is high speed tires with high rolling resistance, but it is common across all models. MPGe drops from 116 to 101 (-15%) with that change. On the Model 3 the RWD gets 132 mpge, and the 2-motor AWD with more power gets 131. The performance version is still 2-motor but larger ones I guess, but you also get the bigger high-speed tires... drops to 113. So there appears to be a ~15% hit due to tires and wheels, but nothing else makes much difference.

Gas Mileage of 2022 Vehicles by Tesla

Search by Manufacturer. Search by make for fuel efficient new and used cars and trucks

fueleconomy.gov

Electric Cars, Solar & Clean Energy | Tesla

Tesla is accelerating the world's transition to sustainable energy with electric cars, solar and integrated renewable energy solutions for homes and businesses.

www.tesla.com

Tesla randomly will give specs, but I guess it's generally a secret. I've heard that they like to make running changes, so you never know what you will actually get...

The Audi E-trons have ~15% hit from wheels and tires as well. But as you said there is an even bigger hit by going to the sport version.

Gas Mileage of 2022 Vehicles by Audi

Search by Manufacturer. Search by make for fuel efficient new and used cars and trucks

fueleconomy.gov

 

[Bobu]

It’s not only the wheels. I had identical wheels on both e-trons and still got about 25% more range with the non-s modell. But as written above I‘m pretty sure the number of motors is far more relevant than the size of the motor for range. I‘ve no idea why you don‘t see similar range differences with the different Tesla motor configurations.

 

[Porkchopexpress]

As others have posted, smaller electric motors don't really equal more efficiency. Having 4 wheel drive instead of 2, (which frequently correlates to higher power trim levels on EVs) does decrease range along with the wider tires required to put that power down to the pavement.
I think the solution to electric truck range will eventually come down to adding batteries and possibly electric motors to trailers.

 

[rruff]

There is some other factor besides power that isn't being accounted for.... if Tesla can increase power with only tiny reductions in efficiency. The E-tron S even has less power than the Teslas and is much less efficient. Granted it's a bit larger vehicle than anything Tesla makes, but 63 mpge vs 116 mpge for the Tesla S Plaid which has over double the HP! The E-tron S is even worse than the Rivian at 70 mpge.

Gas Mileage of All-Electric Vehicles

Gas Mileage, greenhouse gas emission, air pollutant emissions and of model year All-Electric Vehicles

www.fueleconomy.gov

 

[rruff]

Having 4 wheel drive instead of 2, (which frequently correlates to higher power trim levels on EVs) does decrease range along with the wider tires required to put that power down to the pavement.

On the Tesla 3, AWD vs RWD is <1% different... the AWD even has more power.