Comment by porphyra
19 hours ago
I explained this in my other comment but I'll paste it here:
The thing is that ICE vehicles are so inefficient to begin with, but a towed trailer needs the same amount of energy regardless of what is towing it. Imagine a trailer takes 1 unit of energy to move, and ICE truck takes 5 units to move itself, and EV truck takes 1 unit to move itself.
The ICE truck towing it would go from 5 units to 6 units, reducing the range by 16%.
The EV truck would now go from 1 unit to 2 units, reducing the range by 50%.
So the better your efficiency, the worse you are at towing. Ideally EV trucks would have such a huge battery that even when the range is reduced by 50%, it is still as long as a gas truck's range, but modern battery technology is still too sucky to achieve this.
This analysis doesn't make sense to me.
An ICE vehicle isn't less efficient because the frame itself takes more energy to move, it's less efficient because the engine burns off a high percentage of its energy as waste heat.
But that will be true regardless of what the load is. If the ICE truck takes 5 units of energy to pull itself compared with 1 unit for the electric truck, that implies that the the truck chassis only actually requires 1 unit to move, but the ICE engine burns off 80% of its energy as waste heat. The engine is only 20% efficient.
Now if you start pulling a trailer, you have (in total) 2 units of energy worth of load. But if the ICE engine is still only 20% efficient, then it will take 10 units to pull both, rather than 6.
I can believe that this effect is real (electric cars suffering more range loss when towing), but it seems to require an explanation beyond this one.
It is more complicated with ICE though because the efficiency changes with load amount, and what power output an ICE is most efficient in can be designed with towing in mind. Ive seen 90s trucks that got 18 MPG empty on a good day, but then when loaded with twice or more the vehicle's curb weight on a trailer merely drop to 17 MPG.
Generally this is only true for ICE with an abundance of extra power to start with, but that is basically every truck and most other cars for the last 25 years.
It's the effeciency curve. ICEs are more efficient with heavier loads - more fuel goes to useful work.
There's also that electric cars have a marginally better drag coefficients for a few reasons - ICE vehicles have a bot less incentive and they need to use more air for cooling - so the drag from a trailer will be worse, as a percentage extra, on the average electric vehicle.
Why would an ICE be more efficient with a heavier load?
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The range on my diesel truck drops in half when I pull my trailer. Roughly similar to an EV towing. It also happens in winter (not quite as big a drop). Thats what most folks care about. But people like to overstate it as a dramatic downside of EVs.
But the range on the Cybertruck is starting much lower, so that halving is a lot more painful.
I frequently tow between Washington and Montana, and I only have to fill up the F-350 once or twice when loaded. You would need to recharge a loaded Cybertruck 5+ times on that same route. My 11 hour drive just turned into a 15 hour drive in ideal conditions. And I don't think there are the latest superchargers available on most of the route, so the time spent charging is likely much higher.
Don't get me wrong, I like EVs and have a Model 3 as my daily driver. But I would never get rid of the gasser given today's battery tech with the number of roadtrips we take.
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The problem is charging stations are few and far between in rural areas already.
> This analysis doesn't make sense to me.
Because the numbers are a bit off. I've towed a lot, gas trucks do not lose 15% when towing. My old F150 went from 18mpg to 10mpg. My super duty went from 16mpg to 8mpg.
The advantage is that gas is so energy dense we just routinely equip trucks with 35+ gallon fuel tanks. There's no battery option equivalent yet.
I think what it actually says is that EV has short ranges.
If a car held gas worth of 750mi of driving and towing would reduce it to 500mi, and your actual driving distance was significantly less than both, the difference would be unnoticed.
If a car held gas worth of just 500mi with extremely well optimized aero and driveline loss minimization and highly efficient regen, and a towed trailer would absolutely ruin that, and your driving distance was too close to the diminished range, you will notice that.
If your EV held like 12500kWh of charge for like 3000 miles of range, and it was mostly for Costco runs, towing range penalties will not be among your top concerns.
It’s also the part that if you go from 400 miles to 200 miles between 5 minute gas fill ups, eh. But doubling 20-30 minute charges? Super annoying.
But boy does my model Y tow tiny trailers well.
The EV trucks usually do more like 30-40 minute charges due to the large battery. But also, gas vehicles don't do 5 minute fillups either, AAA says average is about 15 min.
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That's part of the answer, but the other part is that towing is going to reduce range significantly regardless of your fuel. With a gas or diesel vehicle that's not a big deal, because you can fill back up in 5 minutes or less. With an EV, it takes 20+, and the fast charging locations are less plentiful than gas stations. If you're not towing, that doesn't matter too much, but when you have to charge 2-3 times as often due to towing, it becomes a real issue.
Fast charger stations also rarely make allowances for cars with trailers. You often have to detach the trailer in order to get into the charging bay or park across multiple.
Not to mention you can't really charge while having a trailer.
This would only make sense if the EV efficiency gain were due to lightness of the vehicle or better aerodynamics. It's definitely not the first, and don't imagine the second is a big factor but maybe I'm wrong. I'd even expect EV to help here because a heavy trailer takes more energy to get moving that can be partially recouped when regen-braking.
Is it just that these EV trucks don't have multiple gears to tune themselves for towing? Like how many EV cars are geared for city speeds but suffer on the highway. I know dual-motor ones have different ratios, but that's still 2 speeds vs 6-10. Edit: Could also be about engine tuning.
The second is in fact a big factor. The vast majority of a car's drag is aerodynamic drag since it grows quadratically with speed; rolling resistance and stuff are much smaller at highway speeds. In order to compensate for the tiny capacity of batteries, EVs try really hard to squeeze out better efficiency in aerodynamics and other sources. That's why EVs have flush door handles and stuff.
That would explain it if it's large. But if this matters so much, why don't the diesel trucks make all the same resistance/aerodynamics improvements? The only EV-specific advantage there is not needing air intake... again I have to say, intake drag doesn't sound huge but maybe I'm wrong.
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A large amount of the energy of an ICE is wasted as heat and noise. Some of that is a constant factor that isn't sensitive to load. So when increase load, it doesn't make as much of a difference to energy used.
By contract in EVs, much more of the energy is going towards moving the vehicle and therefore both weight and air resistance greatly affect the amount of energy use.
The heat and noise do scale with how much gasoline you burn. That's part of the whole ICE being less efficient than battery in terms of input chemical energy vs output mechanical energy. It cancels out when you're calculating regular vs towing range. The engine is the same efficiency either way.
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You can’t recoup the braking energy when the trailers have their own brakes.
True that
I'm confused by where efficiency comes into this.
The efficiency is usually defined as the energy the car can use to move itself over the energy going in (electrical, or chemical for gas). If an ICE is 20% efficient then using 5 units means you get one unit out. Towing a trailer that doubles the load means you need 2 units out, which means you need 10 units in. So you get half the range either way.
The engine doesn't get more efficient just because you hook a trailer to it: it's still 20% efficient regardless.
ICE engine efficiency is not a flat figure, it varies by RPM and load.
“20% efficient” is like an EVs “270km range” - how far you can actually drive an EV depends on temperature, speed, etc.
I think you're missing the cost of ownership in your efficiency calculation. EV's without incentives cost a lot compared to ICE so much so that the savings don't equate usually until I hear year 4 of ownership. Now that's getting better I mean look at the new Bolt or Ford Fathom 30k Retail usually (which I think is where there's a lot of room in small midsize trucks and EV's)
> EV's without incentives cost a lot compared to ICE
This is highly variable. My Lightning was cheaper than the ICE version I had been shopping for. It has been better for my wallet from day 1. And it has depreciated less. The credits did distort the market for a while, though, that is for certain.
>So the better your efficiency, the worse you are at towing
The fuck?
best explanation of towing I've heard great job.
Once I discovered that the entire EV battery holds only 2 gallons-of-gas-worth of energy (roughly about 65kwh) , all of the range issues made a lot more sense.
Half the range for 1/20 the energy is a win no matter how hard you spin it.
Not when you are towing
Drivers care about range and cost per mile. The EV is better for one and worse for the other, not strictly better.
I don’t think this is true at all. If towing the trailer doubles the energy required at the wheels (and both engines maintained the same efficiency under the additional load) then both ranges would be halved.
In practice, diesel engines can become more efficient under additional load, and it obviously varies between models but it’s not a 16% vs 50% difference like your example.
The reason EVs don’t tow well is they don’t have a high enough range to begin with. Diesels have nearly double the starting range of an equivalent EV, and storing additional fuel on board is an option.
Getting some downvotes on the above. I’d appreciate if those who disagree explain why they disagree.
The anti-EV crowd is dominated by people with very strong political ideology, I wouldn't take the downvotes personally.
So the EV still beats the ICE vehicle threefold (2 units vs 6 units), it just _feels_ worse (half as efficient as without a trailer) so you declare it _is_ worse.
With that type of reasoning, let me guess, the competitor you work for is General Motors?
EV beats ICE in isolation but without just as much charging stations as petrol stations the advantage is theoretical. Also you need faster charging too (I heard BYD latest tech can do this, can Tesla just license?)
A federal law could easily fix this though, but you would need an administration that cares about climate change or at least about EV
I think the whole thing about climate is kind of disingenuous but that's another topic. Mining the minerals for EV's is utter strip mining and terrible. China is selling it's future away. Look at the story of Mountain Pass Mine in California and do 20-50x that in China at less efficiency.
Efficiency was brought up to explain the real problem, range. I didn't fill up between Reno and SF in my F350 towing a massive trailer and still had plenty of fuel to spare. A cybertruck would've barely made it past Sacramento with a much lighter load and would've taken much longer to fill up.
Actually from Tahoe to Sac is probably one of the better stretches to pull that off, it’s all downhill.
That doesn’t change the gist of your comment however - which is correct. (I’m a happy Bay Area Rivian owner who’s made that trip often)
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IMO it is worse. And I thought I said where i worked in my original comment. You just can't get the range to work on EV's and towing (my personal opinion) large pickups have big gas tanks and it's quick and easy to fill up. It's all about ergonomics. Yes an EV with a full battery vs a ICE with a full tank EV will always be more 'efficient' but day to day it doesn't add up.
Ergonomics and ease of use are why people get cars. Ergnomics right now to me are reason why EV's in America don't sell well. Infrastructure. If every apartment complex and shopping mall had chargers or we had a novel way to charge a battery like an ICE engine then yeah it will take off. Culturally though I think we just love gas stations, emissions and pollusion.
> Ergonomics and ease of use are why people get cars.
It's why I got my EVs, for certain. It would be hard to convince me to go back to the inconvenience of a gas vehicle at this point. I'm hooked.
They put the competitor they work for in their comment, it was not edited, it was there when you posted this reply.
Excellent sleuthing, either way.
Yes, it was a dig at GM.
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Dude, your comment does not compute.
Care to clarify with actual math? We are a technical audience here.