Cold-weather range hits aren’t as bad for EVs with heat pumps
Cold-weather range hits aren’t as bad for EVs with heat pumps
arstechnica.com
Cold-weather range hits aren’t as bad for EVs with heat pumps
45 comments
-
-
Actually, I'm surprised they weren't using them long before. It's basically AC with an extra valve. Thought they get priced like they're some sort of new technology.
-
Vapor injection is the new technology. It's why older heat pumps were useless below 32f.
-
Vapor injection becomes an excuse to downsize the compressor and lowers the cost, it seems. You could easily go lower than 32 if you oversized the pump before EVI, but those were only in specific heatpumps.
-
-
I suspect the reason for that was that the pumps used in car ACs are not really very powerful. They were alright for cooling the car down, but for heating heat up in a cold environment you need a fair amount of throughput, they work if you have the throughput, but you need it to be there.
They work by pulling ambient heat out a large part of the outside and dumping it into the small inside. You need many times the contents of the interior to warm up if it's a cold day outside. Thus you need a lot of air and if you want it to happen in a reasonable time frame you need quite a powerful little motor. The ones on houses are fine because they're huge anyway.
-
It uses the same amount of energy to create cold as it does to create heat.
-
They also need to be able to get the cold side colder than the outside air so once it gets too cold they don’t really work. There can also be some problems with condensation but when they do work they’re great.
-
-
I reckon they thought seat heating and steering wheel was enough, and it kinda is for the most part
-
As someone in a rural state, cold weather range is one of my chief concerns. I work from home but on the weekends travel to far away backcountry areas to ski.
I'd like to get a full EV when my current lease expires(2.5 years) but the pool of cars that are affordable, have AWD, and 300 miles of range(aka 180-225 in winter) is quite limited.
-
Chevy Equinox? I guess it depends on what you call affordable and how long the $7500 federal tax credit survives
-
Not a bad option but still below 300 miles with the AWD.
-
45 comments
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.
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?
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.
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
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.
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.
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.