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Why does Tesla use a Resistance Heater instead of Heat Pump

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ReGas? You mean refill? Actually, if everything is perfect as it should be, no gas will ever leak the system.
Has anybody in the world ever refilled their fridge? No..
Same should be with vehicles. My old BMW has not been refilled with refrigerant for 19 years.
But actually, my dealer added some to Leaf. I'm afraid it might be scam, can't be sure.
They said it lost 75% of the gas. But AFAIK, system will never ever work if so much is lost. So who knows now
did they actually refill or just scammed me.
2014 Leaf.
What I can say that for HVAC to make some heat user HAS to switch on HEAT+AC mode (dehumidified heat)
So if only heating is activated, heat will not be generated as HVAC it tries to heat with HP only.
If HEAT+AC is activated, it tries to use compressor (that doesn't work) to dehumidify and PTC to heat up.

It is possible that refrigerant is low and system tries hard to make some work but is unable. If software is well
made it will not try to do that with low pressure and switch the system off.

Cars are subject to more vibrations that a home refrigerator and frequently the refrigerant will eventually leak out. If a fitting doesn't work loose, a small crack in one of the lines can develop.

My last car was one of the last with Freon (a 1992). I put off retrofitting it for a very long time, but eventually the A/C quit working because the Freon leaked out. I think one of the fittings had worked loose after 20 years.

Seems scam, especially after "inventing " 1234yf gas that practically doesn't have ANY positive sides.
Upgrading all cars in the world from 134a to 1234yf has... welll. no effect.
Being less than 5000 tons of refridgerant on the world per year. That is a drop in the ocean.
Especially considering 134a is pretty ozone-friendly compared to old chemicals.

There was all that hair on fire about Freon being the cause of the ozone hole, but nobody ever explained the mechanism how ozone was making from the surface to the upper atmosphere. Freon is a large, heavy molecule that is also fairly inert. It doesn't react with much and doesn't break down in the environment very quickly. Chlorine, which is the element blamed for breaking down ozone is highly reactive and any Freon breaking down near the surface is going to have the chlorine released react with other things near the surface and get bound up.

PBS used to have a program once a year on underreported stories of the year. At the height of the ozone scare they covered a story that one atmospheric scientist had made a pretty strong case the ozone layer breakdown was caused by the frequent shuttle missions at the time. Most rockets are liquid fueled and the exhaust is mostly water, but the shuttle used solid fuel boosters which produced a lot of chlorine as a by product of combustion and the shuttle flights flew right through the ozone layer with these boosters running.

Chlorine doesn't bond with oxygen when breaking down ozone. Chlorine gas does not bond with oxygen. Instead the gas acts like a catalyst accelerating the breakdown of ozone into oxygen molecules. Ozone is three oxygen atoms bonded together and the oxygen molecule is a pair of oxygen atoms. Left on its own ozone tends to break down into two atom oxygen, but chlorine speeds up this process. Sunlight causes some oxygen in the upper atmosphere to combine into ozone.

Ozone is being created and breaking down all the time, but under normal conditions enough sticks around to add a protective layer to the atmosphere. Chlorine speeds up the breakdown process which reduces the overall amount of ozone.

I haven't seen any follow ups to this story in years, but the ozone layer began to come back when NASA cut back on shuttle flights and they are now talking about it healing completely in our lifetime. The last shuttle flight was in 2011. There may have been some solid fuel rockets leave the atmosphere since 2011, but it's been very few.

I'm pretty sure the profit margins on the gases used now for coolants are much larger (the Freon that was banned was old enough to be public domain), so the chemical companies that make the stuff are probably pretty happy with the switch. The switch from 134a to 1234yf might have been driven by the patent status of 134a. I just did a quick search and it looks like the patent for 134a is due to expire in October 2020. It looks to me like they are doing the same thing pharmaceutical companies do when patents run out on their drugs, they come up with something which is virtually identical they can patent and charge an arm and a leg for.
 
Perhaps that means that the model S interior refresh will come with a heat pump?

Eh, they are really slow to update Model S/X now days, Raven motor aside. Things in various of stagnation/decontenting/etc

For example:

-Model S is still using an external coolant heater instead of it's inverters even though it has the new PM front motor. At this point, Model 3 is basically doubling the coolant/battery heating power of Model S, even though it has a smaller pack. Also it seems their inverter based heating can do constant power regardless of SoC. Low SoC on S/X results in low power from the resistive heater.
-For those people who got the remote windows up/down feature, the Model S is notably excluded. I don't believe it has window controllers that are on the canbus, unlike X, 3, and likely Y.
-Bluetooth phone key doesn't work (Elon tweeted a software update would make it work with S/X I think over a year ago, I suspect it's missing hardware)
-200kW supercharging claimed as of Raven from last June, but it still doesn't work. It doesn't even really work at 150kW either, stays there for a couple seconds/minutes max then drops to something pathetic like 70kW, even on a warm pack at 20-30% SoC. It is notably worse than my old early 90kWh pack - which at least predictably stayed well over 100kW from 5%->~55%. It's not just my car - see "my tesla adventure" on youtube. Tesla support said "it looks normal".
-At some point I believe 12V constant power was supposed to be provided from the HV pack to reduce cycling and phantom drain through the lead acid battery. This doesn't seem to work in my Raven, if it ever existed. The car wakes up every once in a while for 3-4 hours to recharge the lead acid battery. I assume this works right for Model 3.
-High speed home charging was downgraded, max available 48A from what used to be 72/80A.
-They've figured out that they can remove about half the fasteners of stuff all around the car and they can still roll the thing in one piece to the customer - like the washer fluid lines under the hood. Constant rattling from many places because so many are missing.

So - we're a bit behind. I wouldn't count on heat pump being in S any time soon. Unless it lets Elon get to 420 miles range ASAP.

I will now step down from my soapbox.
 
In case my participation on this topic is being referenced, the title of this thread is "Why does Tesla use a Resistance Heater instead of Heat Pump"
So I've approached the topic from that point of view, "what are the reasons (engineering challenges)". I never meant to imply it was impossible, only that there are issues to address and cons that weigh against the pros.

I am excited to see how they addressed those issues.
 
This is a classic example where the term 'fan boy' comes from. Defending a brand and it's decisions for the only reason that they can't possibly be wrong. Everything Tesla does is the best decision and is the right one. Yes Tesla's HVAC system is efficient. But a heat pump is even more efficient in many situations. Not in all, but in many and overall it's making the car more efficient. Case closed.
 
Fan boy here.

Tesla made the right choices for 10 years and now 4 dominant offerings.
Heat pump makes sense, but so does a resistive system.

Very interested to see the real world efficiency of the Model Y.
Won’t be buying one, heat pump or no.

And it won’t matter if the Cybertruck has a heat pump or not to me, I’ve reserved based on very different wants and criteria.

I don’t get the passionate advocacy on either side of this thread.
I have a heat pump in our house, and that makes sense, but so would hydronic or other heating methods.
 
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My English is not native and I still don't understand this. Could somebody enlighten me?

>>when the outside temperature is cold and your vehicle is heating or supercharging.

1. Temp is cold and vehicle is heating
- if there's enough humidity (fogging) in the car, naturally A/C (a.k.a. a sort of heat pump) kicks in and makes noise.

2. Supercharging
- it is necessary to cool the battery while supercharging, so it makes sense to use A/C to cool the battery.

So some people can point out that the word heat pump means both directions to exchange heat, but what about (2) above?

Hmm.
 
My English is not native and I still don't understand this. Could somebody enlighten me?

>>when the outside temperature is cold and your vehicle is heating or supercharging.

1. Temp is cold and vehicle is heating
- if there's enough humidity (fogging) in the car, naturally A/C (a.k.a. a sort of heat pump) kicks in and makes noise.

2. Supercharging
- it is necessary to cool the battery while supercharging, so it makes sense to use A/C to cool the battery.

So some people can point out that the word heat pump means both directions to exchange heat, but what about (2) above?

Hmm.

2) is regarding heating the pack in cold weather, not cooling it in hot weather.
A warm pack can charge faster than a cold pack, and a really cold pack can't charge at all. The pack preconditioning when you have a supercharger waypoint and pack heating when you are at a supercharger in cold weather can both use the heat pump mode to raise the pack temperature.

This behavior is different than the previous cooling mode only cars, so they are calling out the difference.
 
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2) is regarding heating the pack in cold weather, not cooling it in hot weather.
A warm pack can charge faster than a cold pack, and a really cold pack can't charge at all. The pack preconditioning when you have a supercharger waypoint and pack heating when you are at a supercharger in cold weather can both use the heat pump mode to raise the pack temperature.

This behavior is different than the previous cooling mode only cars, so they are calling out the difference.
Thank you! So

>>temperature is cold and your vehicle is heating or supercharging.

This statement should read (temperature is cold and (your vehicle is heating or supercharging)).
 
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@Dr. J thanks for the link.
Patent with images:
US20190070924A1 - Optimal source electric vehicle heat pump with extreme temperature heating capability and efficient thermal preconditioning - Google Patents

There are a lot of different variants, but here are my major take aways from the patent.

Many versions do not have an ambient evaporator. That eliminates all the frost issues. It also means it only harvests energy from the coolant loop. In some, the system operates like a typical heat pump.

The cabin HVAC contains both an evaporator and a condensor which can operate simultaneously (like a dehumidifier).
The system has some variants with only two port valves, others use an 8 way.

The system eliminates the cabin PTC heater by running the cabin fan and or the compressor inefficiently to generate additional heat along with the 3 style drive unit self heat generation.
 
Plot of operating modes.
The pack (if ambient is high enough) and power train can act as evaporators to the ambient to warm the coolant loop, along with harvesting the waste heat.


SmartSelect_20200315-121420_Firefox.jpg
 
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So many fanbois defending Tesla for not having a heat pump are eating their words now.

@AWDtsla is right in that the Model S seriously needs a refresh. Over 8 years with little changing is unacceptable for such an expensive car. Who would buy one over a Model 3 or Y for double the price?

People that want more luxury than the econobox feel of the Model 3 and Y. Many luxury cars go 8 years without a complete overhaul and just incremental improvements.