Retaining 90% range at -40°C sounds like a game changer, almost too good to be true. I'm definitely going to need to see some third-party real-world range tests to validate those claims before getting too excited.
Note that this article's summary has a significant error compared to the original press release[1]. The article says "90% range", whereas the press release says "90% capacity retention".
This is a big difference because there are all kinds of other factors besides energy capacity that can affect the efficiency of the whole system, and therefore affect range.
Most notably, air is about 28% denser at -40°C than at 25°C, so drag is about 28% higher. So you would expect roughly 28% less range at high speeds even if the battery has no capacity loss whatsoever.
As someone else mentioned, climate control also consumes a lot more power when it has to maintain a larger temperature difference between inside and outside.
> Most notably, air is about 28% denser at -40°C than at 25°C, so drag is about 28% higher. So you would expect roughly 28% less range at high speeds even if the battery has no capacity loss whatsoever.
With my gas car, I haven't noticed 30% worse fuel consumption at –30°C compared to +30°C [0]. To be fair, I haven't closely measured the fuel consumption at different temperatures, but I probably would have noticed such a big difference. This is just anecdotal of course, so your values may actually be correct.
[0]: It does occasionally get down to –40°C here, but my car won't usually start then, so I've slightly shifted your temperature range to the values where I've driven most.
It won't be as noticeable on a gas car because it is probably starting out around 30% efficiency (as compared with ~90% for an EV). This is a major advantage of gasoline, in a sense, because it means we have already engineered the package to account for a lot of wasted fuel.
Ah, so then the air temperature should reduce fuel consumption by 30%×30%=10%, which does seem to roughly match my experience. Thanks for pointing that out!
Internal combustion engines are actually more efficient in cold weather than hot weather. But the other factors like drag outweigh the increased efficiency of the engine. And since gas engines are so inefficient to begin with you don't notice much of a difference. https://physics.stackexchange.com/questions/270072/heated-an...
Gas cars produce more power at lower temperatures - more oxygen gets into the combustion chamber, and the engine also can run more advanced spark timing without as much worry of detonation. This is why turbochargers have intercoolers.
Note that a 28% increase in drag results in a roughly 22% decrease in range, because 1/1.28 ~= 0.78. Also there are other losses (like rolling friction and constant loads like headlights or cabin heat), so range doesn't scale perfectly with drag. Drag is the main source of loss at highway speed, however
I drive long distance weekly on my gas car. Full tank in summer (+20C) gives me 520 km, while in winter (-20C here) I get 430-440 km. I noticed it on my current and previous cars. Maybe it's thicker oil and worse car efficiencies in winter ? And that's despite that full tank of gas has more gas in winter comparing to summer, gasoline is denser in cold temps.
It's the majority, but overwhelming or not surprisingly appears to depend on car model, at least per some calculations someone on reddit ran [1].
I'd add though that rolling resistance tends to be higher, on average, in winter too. When there's often a bit of snow on the roads... Less so on high speed highways admittedly.
For most cars driving through air, at sea level, on planet Earth, at normal speed, the drag force F is proportional to the square of the speed (v^2).
That's not exponential because the speed (v) is not in the exponent. In fact, it's quadratic.
Corollaries: The power required to push the car at speed v will be proportional to Fv ~ v^3. The gas spent over time t ~ energy spent ~ power time ~ v^3 * time.
Define ‘high speeds’. There’s a reason race cars look like they do, to the point of having serious problems driving at speeds just a bit below highway speed limit.
I don't imagine the difference is very significant on long drives. If the car is cold soaked at -30, it uses about 10kW for the first 3km. Then everything is warmed up, and the ~25% difference is increased consumption, not decreased battery capacity.
As long as you have a heat pump harvesting the waste heat to keep the battery up to temp.
But might be significant on short drives, 10kW for the first 3 km is massive.
Yeah, this heat up effect is massive for around-town use. We have had below freezing weather for two weeks, which is very unusual here in Annapolis. That’s had a huge impact on my wife’s use case, which involves a bunch of 5-10 mile trips to drop the kids off at school, go on a grocery run, pick the kids up, take the kids to math tutoring, etc. She ran out of charge the other day during drop-off b/c the “37 miles left” we had the night before was actually a lot less than that accounting for warming the battery up the next day.
And human occupants will still run the heater more in winter. But it sounds like there could be a future where makers offer a sodium battery and heat pump version of their cars for sale in colder climates.
Running a preheater loop for the heat pump from the systems than need to be cooled, inverter and motor that run better cold,and other optimisations could likely supply cabin heat with very little battery draw, solar pv blended into the exterior could zero that out on an average basis,but 40 below is nothing to play with unless you know exactly what you are doing, even if they say it will still work.
IIRC there are some surprising holdouts, at least in the NA market. For example as far as I'm aware the Mustang Mach-E still ships with a resistive heater.
Vehicle ASHP do little in deep cold temperatures, since the evaporator is necessarily so small. They're mostly effective in the 0-15C range. Note that all EVs have PTC heaters, regardless of heat pump. The PTC is what does most of the work for getting the interior to temperature quickly (they're 5-10 kW).
The VW id.3 costs about 30k. It doesn't have a heat pump by default, but it's a 1,200 EUR add-on. Which probably makes sense; in some markets where it's sold it doesn't really get cold enough that one is of significant benefit.
Interestingly, the Hyundai Inster (20k EUR) and Renault 5 (25k EUR) both have heat pumps as standard equipment.
just fyi for the MY23 and older software 3.8/9 should be available for update, which is a pretty significant upgrade compared to 3.2 or the 2.x builds (which I don't think a MY23 should have but idk).
There's one. Go to a Car and Driver article about cars with extreme ranges, namely those over 650 miles, and they will start listing out particular years' models over a 10 year period in order to get to even ~10 models, and most of them are EcoBoost or variants or poor selling hybrid versions of other cars.
Assuming a 1000km range is a very strange thing to do, as it's a fringe feature that almost no one needs or wants! Recall that "almost no one" means that there's still some, an existence of a handful of people on HN is quite consistent with "almost none."
Of course I didn't pick it for range, I looked at price and miles of what the local carmax had and then separately looked up how tall the top of the windshield was.
Which I would expect to typically find something that's, um, fairly typical on characteristics I wasn't selecting on.
my 2010 F-150 with the notoriously terrible 5.4L gas engine seems to manage 1000km range. there's absolutely nothing efficient about it, it's just got a big gas tank.
Comparing range of gasoline cars is idiotic. There are plenty of cars with long range (1000km), and they all have 60L+ fuel tanks and most run on diesel (which gives you ~15% more range per liter). It'd even argue the same for BEVs. More battery is more range.
You mean EVs? Yeah, none that I'm aware of. But petrol/diesel cars? Loads of them. Even my 400bhp Volvo XC60 will easily do 650 miles on one tank of fuel. A diesel one will do 700-800. And a diesel Passat will go over 1000 miles on a tank without trying. Hell, even my basic 1.6dCI Qashqai could do 700 miles on its 55 litre tank
Cool, I guess when I did 700 miles on a single tank of fuel driving Switzerland to Italy and then again driving Italy to Austria and then again Austria to Netherlands this summer I just imagined it. My total for the 3000 miles was 38mpg(imperial).
Also you are quoting a value for the B5, which is not what I have, mine is a T8(and before you ask - no, I didn't have any opportunity to charge it anywhere on the way).
> Fuel economy tests show that, in city driving, a conventional gasoline car's gas mileage is roughly 15% lower at 20°F than it would be at 77°F. It can drop as much as 24% for short (3- to 4-mile) trips.
The temperature difference should in principle increase thermodynamic efficiency. You get loss of MPG from other factors though mentioned in the link, like increased friction of moving parts, idling to warm up (0MPG), defrosters/seat heaters, lower tire pressure, denser air to drive through, winter fuel mixes which may not have as much energy, etc.
Sticking a piece of cardboard over a portion of the radiator was a common sight during the winter when I was growing up in rural Ohio. I didn't think our winters were that cold, but maybe late 70s to early 80s vehicles were more susceptible to running cold.
I had a car that developed a stuck-open thermostat and did the cardboard trick to get by until I could replace the faulty part.
I've had that happen, too, on a [more] regular car. I drove a Mustang 5.0 from Oklahoma to Oregon, and as I went through eastern Colorado the coolant temperature steadily dropped until it was resting at the bottom of the gauge. I don't recall whether the gas mileage suffered noticeably or not during that phase of the drive.
There are a bunch of things going on, and some people's measure of efficiency needs work.
1) winter blend fuels have less energy per volume, that doesn't make your engine any less efficient by energy but it does by volume of gas
2) lots of temporary cold effects: fuel vaporization, thick lubricants, etc. these things become less of a problem as the engine warms up but some energy is still lost on long drives
3) air resistance: all aerodynamic forces are linearly proportional with air density. At a constant pressure there's about a 15% difference in air density between the hottest and coldest places you can drive (and thus 15% less drag on a hot summer day than a cold winter day). aerodynamic forces are proportional to the square of your velocity and they become the largest resistive force around 50mph -- so at highway speeds you're losing efficiency because you have to push more air out of the way
4) energy used to maintain temperature: this is hard to calculate but some engine power is lost because the energy is used heating up the engine block and lost to the environment
5) the Thermodynamics 101 engine efficiency goes UP with increased temperature, but it's got a lot of real world effects to compete with, no spherical cows and all
Assuming you can get the car to start (mine needs an engine warmer at that temperature), it takes at least 15 minutes of driving to reach that temperature. Unless you’re going on a longer trip the engine most likely wont be warm by the time you reach your destination.
I had to drive in -30C once, the engine could not get up to final temperature after 2 hours of highway driving because I had to run cabin heater at full blast on windshield and side windows so they didn't cover with fog inside. But that was in very old low power car.
My tiny diesel car (2008 Toyota) needs its auxiliary heater below around -15 C for highway trips. It's a switch in my dash that burns extra fuel, otherwise the engine won't get up to or stay at temperate.
Pretty normal with diesel as it gives off less heat than petrol. I have a van with an 88kW engine, and even at -5c I can see the coolant temperature drop when I am idling down hill and have the heater on. Any colder and it's worth blocking the radiator with cardboard.
I once had a condo with parking in a cave that was above freezing even when outside was -30 C (or F, close enough at that part of the scale). It was a great winter perk.
Since the Lithium battery prices dropped, there are many Sodium battery companies simply abandoning the research or shuttering. Not a good sign when smart people jump ship.
The Na cells also have lower energy-density, and currently fewer viable charge cycles. One can still buy evaluation samples, but it takes time to figure out if the technology will make economic sense.
This is a big difference because there are all kinds of other factors besides energy capacity that can affect the efficiency of the whole system, and therefore affect range.
Most notably, air is about 28% denser at -40°C than at 25°C, so drag is about 28% higher. So you would expect roughly 28% less range at high speeds even if the battery has no capacity loss whatsoever.
As someone else mentioned, climate control also consumes a lot more power when it has to maintain a larger temperature difference between inside and outside.
[1]: https://www.catl.com/en/news/6720.html