The main reason why the US ID.4s don't come with heat pumps.
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I'm betting the real reason is simple cost savings. Those in cold climates really need the heat pumps, while those who live as far south as latitude 30 like I do wouldn't use it that much if we had one, so we'd probably rather have the lower price
Don
Don
They still have on-board A/C units so I am not sure what the connection of refrigerants has to do with having an on-board heat pump.
Heat pumps do not work so well below 32F when pulling heat from the surroundings and if the VW system is not able to collect enough heat from the motor and/or the battery the system would not work so well in the areas with very cold winters.
Heat pumps do not work so well below 32F when pulling heat from the surroundings and if the VW system is not able to collect enough heat from the motor and/or the battery the system would not work so well in the areas with very cold winters.
"Money money money,
it's so funny,
in a rich man's world"
Totally agree it comes down to money and wanting to keep the ID.4 cost competitive in the US auto market. The CO2 system VW have opted for is relatively expensive to implement. Our electricity is relatively cheap compared to Euro nations. The trade off seems fair.
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The US uses R1234yf vs R744 (VW, & EU?). So, it's straightforward for VW to equip the ID.4 with heat pumps for countries that have approved the use of R744 in Automotive. It'll require re-engineering the AC system and be expensive to have two types of AC refrigerant systems.
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For the sake of our planet, R722 has lower GWP = 1 vs R1234yf GWP = 4. Even, Tesla is in the process of switching to R744 from R1234yf.
iD4 Pro Performance Max - Ordered July 2021 - Delivery December 2021 (hopefully)
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In Canada and Europe iD4s come with a heat pump. The US iD4s have a lot of features stripped out, heat pump is but one.
That's kind of the key - there is a sort of sweet spot in terms of temperature where the heat pump could be a win. Below that the heat pump is ineffective, and you have to use resistive heating. And there is sort of an upper limit which is going to be the spot at which preconditioning, seat heaters, sunlight blasting in through the roof window, and heated steering wheel are adequate to keep you warm enough.
That is no doubt true. Given the choice of an R1234tf equipped EV vs an R1234af equipped fossil fuel car I'd want the former. EV prices have to be competitive in order to dislodge fossil cars, even if that means a slightly less than optimal A/C refrigerant. It is a compromise unfortunately. The alternative of R152a has a GWP of 124, which is also way better than R134a with a GWP of over 1,300. 4 times as bad sounds real bad, but in the perspective of where we have to come from, we are much better off with either R722 or R1234yf.
Transitioning away from fossil fuels to electric drive is job #1. Job #2 (among others) will be to optimize the A/C refrigerant on EV's. Let's win the war not the battle.
Another factor is that at higher temperatures like the southern half of the US, R744 systems have lower efficiency. This leads to 2 things, people complaining about not enough AC, and a higher power draw on the batteries to get the same amount of cooling, which lowers range. This means overall a lower climate effect of R1234af systems in those areas. Especially when the refrigerants are collected and recycled as is the law in most areas, the main release of them would only be in accidents. We could get some canadians with their ID.4 to come to Arizona when its hot and do some comparison tests, and VW probably has already done those tests.
And the fact that the R744 compressor has to operate at 6-10x the pressure could lead to a shorter life of components, or reliability problems that won't show up for a while (such as leakage of the refrigerant and having to recharge more often, and may be real expensive for a while since few have the special equipment and training to work with R744 yet.)
Edit: the critical point is 88F (31C) where the efficiency of the transcritical R744 system quickly drops. And if you like thermodynamics like me there are great AC design resources showing this.
And the fact that the R744 compressor has to operate at 6-10x the pressure could lead to a shorter life of components, or reliability problems that won't show up for a while (such as leakage of the refrigerant and having to recharge more often, and may be real expensive for a while since few have the special equipment and training to work with R744 yet.)
Edit: the critical point is 88F (31C) where the efficiency of the transcritical R744 system quickly drops. And if you like thermodynamics like me there are great AC design resources showing this.
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The heat pump in the ID.4 doesn't work well after you pass like -5 degree F as I recall (might be a little lower) without scavaging heat from other places to supplement it. That's why the Tesla system has the 8 different operating modes, to try and recapture heat from the other components to augment the heat.
It's also why my home heat pump has heat strip backup (pure electric), even here in Florida. Most of the time it runs just fine for our weather, and I can't recall the last time I had to use the emergency heat. But it's there in the event that I need it. We are in the market for new systems for our house, and it's been a journey as heat pumps take up a lot more space for efficiency in both compressor and air handler/coil.
My thermo is really rusty. 1991 was my undergrad freshman year in engineering. LOL But from what I can gather, r744 because of its low critical point, etc. requires multiple steps to get roughly the same output as a r1234 or r134 system, where the critical point is way over 200 degrees ambient.
It's also why my home heat pump has heat strip backup (pure electric), even here in Florida. Most of the time it runs just fine for our weather, and I can't recall the last time I had to use the emergency heat. But it's there in the event that I need it. We are in the market for new systems for our house, and it's been a journey as heat pumps take up a lot more space for efficiency in both compressor and air handler/coil.
My thermo is really rusty. 1991 was my undergrad freshman year in engineering. LOL But from what I can gather, r744 because of its low critical point, etc. requires multiple steps to get roughly the same output as a r1234 or r134 system, where the critical point is way over 200 degrees ambient.
Heat pump technology is definitely there for 0-32ºF usage, it's just expensive. Tesla does not have backup resistive heat, which I think is a mistake, but they do scavenge it from all over the car which is smart and allows the system to work pretty seamlessly even when it's very frigid out. People do have trouble getting good heat in Canada with the Model Y when it's sometimes -20ºF out, though. That's a situation that proves Tesla should've kept a small resistance heater installed, but they didn't.
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Next revision will have 800 watts heater for heat pump fluid to help with extreme cold weather conditions operation A/C as heat pump. Not sure if Tesla will use 60 amp fuse and 12V supply or HV DC for this heater ( that will heat A/C fluid )
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It will still suffer with Tesla with design on the market now...next revision will have heat strip.
Especially if you camping in very cold weather and there is nothing left to scavenge from Tesla.
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