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Cold-weather range hits aren’t as bad for EVs with heat pumps
(arstechnica.com)
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this post was submitted on 07 Jan 2025
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Is this really an article saying heat pumps are more efficient than resistive heaters? Yes, that is why heat pumps exist.
The biggest issue is the battery itself. If it gets cold enough you can have difficulty even charging an EV outdoors. I would be a lot more concerned with whether or not my battery is well insulated and heated. Heat pumps are great and should be the default, but unless you're going really far or have a very low range EV it's not a huge issue.
Yes, resistive heat is expensive, but that's only part of what makes heat pumps in cars more effective. They don't just heat your cabin, they heat your battery so you maintain range while it's cold out. Here's an article with more details and some pretty infographics.
The heat pumps also preheat the battery so it can charge in extreme cold.
You still need resistive heat as heatpumps don't work below about -20C and those temperatures happen to at least some car buyers.
I don't think that's true? There are cold weather models that can work at COPs > 1.5 at -30C. Are we talking about a sizing constraint for the model here, perhaps?
There are, but then I think you'd have problems with the effective rang of the AC in the summer. To my knowledge this is all about at what temperature the coolant is a liquid and when it's a gas (because that's how you exchange heat).
A traditional AC only needs coolant that does this at summer temperatures. A heat pump tries to use one that will work at colder temperatures as well. A cold weather heat pump goes even further but I think there is a sacrifice in AC efficiency in the summer.
Somone please correct me if I'm wrong. But I'm not sure if a do-it-all extreme cold and extreme hot heat pump exists, and as a car manufacturer you want to put in the one that will fit most cases, as opposed to a house which only needs to operate in the range of the climate it is built in.
It would make sense if the two stage heat pumps use different liquids in the different stages. I don't actually know how these are made, so I can't assert that this is how it works, but I would be surprised if it worked any other way.
I’m pretty sure that’s not how refrigerant (not coolant) works.
Extra insulation around the expansion valve and piping may be necessary. Or possibly heating around them. But the main limits are the size and speeds of the compressor and fan(s).
Home heat pumps are getting much better in colder climates. But I’m not sure of the efficiency in vehicle sized units. I’m really interested in them for a camper project I’d like to build though. But might have to wait for more of the cars that feature them to arrive in salvage yards.
Thank you for the correction. I know the properties of the refrigerant are important, but you're correct that the other side of the equation is how much it's compressed. If it's true that compression plays a larger part than the refrigerant at working in lower temperatures, then that does explain why we wouldnt see them in cars. The rise in cost for both the compressor and higher energy usage could make them less appealing to manufacturers.
Im in one of those places but where im at its rare and at this point I will resist leaving the house pretty massively at those temps.
If it is rare enough and you don't have an emergency that is the right thing. Odds are the rest of your city doesn't have the ability to deal with those temperatures and so you going out will make things harder for emergency workers who must get out. If your city deals with this often then everyone will know how to deal with it and expect you to deal with it. You cannot shutdown your life for something that happens every single year, but if it is just a day or two every 5 years it isn't worth being knowing how to deal with it other than the minimum emergency needs (that is make sure your HVAC system at home can handle it)
I mean its more like we can go a winter without below zero F. Its a lot less common in the last decade and usually it does not last to long and that is really for lows. Highes below zero aren't shockers but yeah we can go some years now without them and for most folks they are doing things while the sun is up. My thing is if I grab a metal doorknob with a bare hand and it is actually painful, then its like ef this im staying inside unless someone forces me out. Even back in the early aughts I had a job that was not wfh all the time like now but did it as needed and I could easily email I was wfh do to the weather being extreme. Its actually the wfh policy outside of all the time type one I like the best. wfh anytime there is a reason to and actually that place was like do not come in if you are sick. if you came in and coughed you would get the maybe you should have stayed home today comment.
Yes, they should have both.
I know the resistive heater in my Volt can't compare to the heat put out by the ICE. Often in the winter we'll have to run the ICE to keep the cabin warm enough. It does have heated seats and wheel, but my wife is the type to set the heat to max until it gets too hot rather than just picking a temp and hitting auto to let the car manage it.
If the heat pump can put out more heat for less energy, that would be a boon. That might be the second biggest issue (next to range) that has my wife vetoing an all-electric car. She gets the next vehicle, but I want the one after that to be a full EV.
Fwiw, I’ve never had a lack of heat from my cars heat pump. It even warms up faster than a gasoline engine would. Most importantly, I can turn it on remotely to get warm before I get in the car. I never had that with a gas engine
Yeah and a lot are moving to heat pumps if they don’t already use them.
https://www.recurrentauto.com/questions/which-electric-vehicles-have-heat-pumps
There’s a list of models that have them.
If you have two cars, one EV and one ICE is a great option. I do recommend whoever is more enthusiastic about EVs get the first one, though.
the ICE generates an insane amount of excess waste heat as a byproduct, so you have a virtually unlimited supply. The Volt is a PHEV so resistive heating was probably not considered super important.
There's no if about it, it is ~300% more efficient.
They are the same issue. Less energy used for heating = more range.
It defintely is a huge issue, considering resistive heaters use 3x as much energy. Most EVs have a "low range" and anything you can do increase it without adding more batteries and weight and cost, especially in winter, is a huge advantage.
The lowest range EV in the US is 114 miles. The average commute is 52 miles. Most EVs sold in the US have a range of 250 miles or more. So a resistive heater eating 10% of your range is way less of an issue than your battery not charging properly in cold weather. Again, heat pumps should be available, but they aren't going to save you if cold weather kills your battery.
No one cares about "average commute" when buying an electric car and considering the offered range. They're thinking about long trips.
Who said anything about batteries "not charging properly"? What does that even mean?
We're not talking about killing batteries, we're talking about electric range. Heat pumps extend your electric range and 20 miles can absolutely be the difference between making it to the next charger or not.
Most people aren't road tripping in their electric vehicle every day. If you don't understand how temperature affects battery chemistry, capacity, and charging I don't understand how you can even be in this conversation.
They can't road trip ever if the vehicle doesn't have sufficient range. I don't understand how you can even be in this conversation when you don't understand basic principles like this.
I understand how it affects all of these. It doesn't cause any of it to "not charge properly". EVs are used in the coldest places in the world with no major charging problems.
My wife has a Nissan leaf with 60 mile range for commuting, I have an old gas hatchback we can take for road trips. Before going off about how rich and privileged this setup is, the Leaf was purchased for 6k, 4k after tax rebates. Hatchback was purchased for 6k 9 years ago.
I'm glad that works out for you.
Not sure how you are being downvoted. You’re absolutely right. Everyone I know that wants an EV wants more range.
I've driven from Madison, WI to Chicago in an EV with ~100 mile range in cold weather. Wouldn't be my first choice, but I was in a pinch at the time. It can work, but getting a reliable charger network is the biggest problem. Made three stops to chargers that were broken or inaccessible for various reasons.
That was a couple of years back, and I think it'd go a bit smoother now. The Chicagoland area has reasonably good charger network outlays (much better than Minneapolis, which is a joke). Still wouldn't be my first choice, but it's workable.
Lots of people consider only their commute. They just don't complain about... Making it to work OK? Or don't announce it? The frequency of 200+ mile trips is vastly overestimated by anti-EV people in both terms of how often they do such trips and how many more people live in dense, urban areas. Lots of people already have shitty, dedicated commuter cars they wouldn't want to sit in for more than an hour as it is. A half-dead 2011 Leaf would still cover my 40-mile round trip. Back when I daily'd a Geo Tracker, I'd take my spouse's normal gas sedan if we had a trip. Or my weekend gas car. The average number of vehicles in US households that own cars is 2.3 cars. An EV can be slotted into most households without any real change.
No they don't.
The frequency is irrelevant. Again, if you want to go on a single trip, literally ever, in the entire time you ever own that vehicle, it needs to be able to make that trip, and it needs to be able to do it in a reasonable amount of time.
If you only ever drive back and forth to work, then I feel really really sorry for you, but you are an extreme minority in that sense.
Exactly.
We do a road trip about once/year, and our trips are long enough that renting a car for that specific trip is impractical.
We have two cars, a hybrid commuter (hopefully an EV soon) and an ICE family car (hopefully an EV soon). That family car isn't going to be an EV until it can do >500 miles/charge, especially if refuels take >20 min. We rarely go that far, but when we do, we need the range because our trips are often >800 miles in a single day (usually only one actual stop for food, we pack lunches). Yeah, that trip isn't very frequent, but it does happen and there's no way I'm spending 2 hours of the trip waiting for my battery to recharge.
Our commuter, however, can absolutely be an EV, because the furthest it will ever need to go is about 100 miles in a single day (25 miles to work, 20 miles to the airport, 35 miles back home, and maybe a stop at a store). But it needs to be able to do that in winter as well as summer, and after a few years of ownership, so 150-200 miles is a better range.
You're an excellent case for my point. Most car-owning households in the US have slightly more than 2 cars. An EV covers your needs 335 days of the year and a gas car covers the other 30 days, yet people act like that's why they need a 7 seat suv every day. I plugin hybrid will be my next move when I stop picking up lumber every weekend and put my little trailer back in use for the once a month "haul"
Yes, one EV can work, but only as a second vehicle.
We're actually trying to downsize from a minivan (we have three kids), to a 5-seater SUV for the family car. The minivan is super convenient, but fuel is expensive (and pollutes) and we both hate driving it. Unfortunately, most smaller SUVs have very little towing capacity, so we need to find something just big enough to tow what we need, but not so big that we lose all fuel efficiency.
If you have a garage or place to easily charge the EV when at home or work, the amount of time saved over the life of the car never having to go to a gas station is dramatically more than the amount of time spent charging an EV on a road trip.
Tell us you’ve never driven an EV, especially in cold weather, without telling us you’ve never driven sn EV in cold weather.
Or maybe you should teach Norway how bad EVs are in cold weather, since over 90% of new car sales are EVs there.