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.
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.
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.
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
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.