Tesla AC -> cool?

JBee

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Very true that using the AC system in reverse to heat the vehicle is one difference between the new Teslas and other cars. But to the point of this discussion, the other main difference is that in ICE vehicles, the pump is powered by the main engine. The power the pump takes from the engine is typically inconsequential compared to ICE’s inherent losses. Where on a BEV, the power used by the pump matters and can noticeably affect range. Tesla most likely does a very careful balancing act to size the pump to give the best cooling performance while minimizing losses.

In college I drove an ‘86 Buick Regal that had a V8 engine. If I left the AC on “Max” for to long I could turn that car into a meat locker. On a particularly hot humid day, I started it and left it running with the AC on to cool it off. Condensation started to form on the outside of the side windows. I still remember the chill I felt getting into that car that day. (Yes I realize the multiple layers of wastefulness in this story. But god, did I love that about that car.)
Purely hypothetical conjecture.

First law of thermodynamics is that energy cannot be created nor destroyed. You did nothing wrong by leaving the V8 running the A/C, except bring about some premature entropy....thx Bill! :eek::ROFLMAO:

Even with the octovalve setup and heat pump Teslas still rely on resistive heating when COP falls under 1 with low external temperatures.
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Challeco

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Very true that using the AC system in reverse to heat the vehicle is one difference between the new Teslas and other cars. But to the point of this discussion, the other main difference is that in ICE vehicles, the pump is powered by the main engine. The power the pump takes from the engine is typically inconsequential compared to ICE’s inherent losses. Where on a BEV, the power used by the pump matters and can noticeably affect range. Tesla most likely does a very careful balancing act to size the pump to give the best cooling performance while minimizing losses.

In college I drove an ‘86 Buick Regal that had a V8 engine. If I left the AC on “Max” for to long I could turn that car into a meat locker. On a particularly hot humid day, I started it and left it running with the AC on to cool it off. Condensation started to form on the outside of the side windows. I still remember the chill I felt getting into that car that day. (Yes I realize the multiple layers of wastefulness in this story. But god, did I love that about that car.)
Ah, I remember them good ol' days where R12 reigned supreme but was bad for the ozone layer. The ability to take bigger bites of heat each cycle were so good though! R134a is still good but just can't take as much energy so it takes more cycles. I love the upgrade of the octovalve from the traditional heat pump design. I will say that the Tesla app doesn't allow me to set the temp below 59F/15.5C without just going to "LO". So, I cannot reliably store refrigerated goods. But, less than 60F from 140F (cabin overheat protection) is still amazing.
I tested the app just now. It took less than 5 minutes to drop from 33C to 19C before I turned off the active cooling. So, I would call this a good system.
 

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Purely hypothetical conjecture.

First law of thermodynamics is that energy cannot be created nor destroyed. You did nothing wrong by leaving the V8 running the A/C, except bring about some premature entropy....thx Bill! :eek::ROFLMAO:

Even with the octovalve setup and heat pump Teslas still rely on resistive heating when COP falls under 1 with low external temperatures.
Unless I am mistaken, my model 3 only has the octovalve. No resistive heater. These last two winters have been reached lows of -21F and our model 3 had no trouble driving long distances across the blue mountains to Pendleton and beyond. I've driven my 1971 F250 across the same mountain range and the weather and wind chill kept the engine from reaching operating temperature. I know because I tried to use the heat from the engine to warm my ass in the cabin. It could not compensate even with 400 cubic inches of 1400 degrees explosion at 3000 RPM.
I was tempted to have my best friend crawl into my lap while I was driving it was so damn cold!!!! But, the Tesla has never left me cold like that... So, whatever the teams at Tesla designed it works really well!!
 

JBee

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Unless I am mistaken, my model 3 only has the octovalve. No resistive heater. These last two winters have been reached lows of -21F and our model 3 had no trouble driving long distances across the blue mountains to Pendleton and beyond. I've driven my 1971 F250 across the same mountain range and the weather and wind chill kept the engine from reaching operating temperature. I know because I tried to use the heat from the engine to warm my ass in the cabin. It could not compensate even with 400 cubic inches of 1400 degrees explosion at 3000 RPM.
I was tempted to have my best friend crawl into my lap while I was driving it was so damn cold!!!! But, the Tesla has never left me cold like that... So, whatever the teams at Tesla designed it works really well!!
Even with the octovalve setup if the COP goes under 1 because of low external temperature the motor electrical coils are used to heat the cooling circuit. Like a resistive circuit, by intentionally pulsing current in an inefficient manner through the coils to create the necessary heat to warm the vehicle.

As for your F150, a peice of cardboard or plastic sheet in front of the radiator would have helped.

Really, Tesla should offer a cold package for colder climates that includes a passenger and battery insulation package. You only need to consume energy to create enough heat to replace what you lose to the environment, so reducing thermal losses means greater range. Good thing about insulation is it is very light weight and cheap, and reduces road noise etc as well.
 


Bill906

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Like a resistive circuit, by intentionally pulsing current in an inefficient manner through the coils to create the necessary heat to warm the vehicle.
I know a person on this forum suggested that might be how Tesla does it. It was never proven or confirmed, and I doubt they do that.

As for your F150, a peice of cardboard or plastic sheet in front of the radiator would have helped.
Beat me too it. Was going to suggest the same thing. Although rare, some vehicles, on very cold days, need to do this. School buses in my home town had black fabric "bras" on the front of them with snaps to open or close the openings. On cold days they'd have the fabric completely close off the air inlet to the radiator.

This isn't exactly what I was thinking of... but you get the idea.

Tesla Cybertruck Tesla AC -> cool? 1658765371933
 

JBee

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I know a person on this forum suggested that might be how Tesla does it. It was never proven or confirmed, and I doubt they do that.



Beat me too it. Was going to suggest the same thing. Although rare, some vehicles, on very cold days, need to do this. School buses in my home town had black fabric "bras" on the front of them with snaps to open or close the openings. On cold days they'd have the fabric completely close off the air inlet to the radiator.

This isn't exactly what I was thinking of... but you get the idea.

1658765371933.jpeg
There's a whole thread and a utube video about it. No reason to do it any different, changing the switching timing to make the motor into a heater only requires some switching offset that can all be done in software without damaging or causing wear on anything. Not the only ones that do it eithe, and seeing the motors have heat exchangers with enough capacity to do so makes it a no extra hardware feature. Just like Tesla likes it.
 
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The Tesla AC is ludicrously powerful and cold. I've measured its actually energy at about 6kW, which is half a ton. A typical small house AC is 2-3 tons, midsize houses 3-4. I have a five minute timer set on my "start HVAC" Siri shortcut, even here in AZ in summer the car is cooled then. It lives outside in full sun. In relation, I've had other ICE with remote start and they never cool that well in the sun without moving.
 


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Are Tesla's air conditioners as cold as ice vehicles air conditioners ?
My only gripe with the A/C in Teslas is that as a passenger if one wanted to turn off the passenger side A/C vents there’s currently no option to do so. I get cold easily and my S.O. is always hot, so the best option I have as a passenger is to aim the direction of the air either all the way to the left or all the way up and even then it’s not good enough. In non-Tesla vehicles, since like forever, the option to just block airflow on the passenger side has been available way before I was born.

Apparently Teslas are capable of blocking airflow to the passenger side but it only happens automatically when the vehicle doesn’t sense someone in the passenger side due to the weight sensor on the seat but that’s it. Which is really damn annoying.
 

JBee

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Some other Tesla forum (TMC?), but around here somewhere too on a not relevantly labelled thread. Tesla patent even mentions using the cabin blower motor and compressor motor in "lossy" mode to create heat. Same effect of using some software controlled waveform manipulation in the motor controllers.
 

SwampNut

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My only gripe with the A/C in Teslas is that as a passenger if one wanted to turn off the passenger side A/C vents there’s currently no option to do so. I get cold easily and my S.O. is always hot, so the best option I have as a passenger is to aim the direction of the air either all the way to the left or all the way up and even then it’s not good enough. In non-Tesla vehicles, since like forever, the option to just block airflow on the passenger side has been available way before I was born.

Apparently Teslas are capable of blocking airflow to the passenger side but it only happens automatically when the vehicle doesn’t sense someone in the passenger side due to the weight sensor on the seat but that’s it. Which is really damn annoying.
There's a temp setting for each side. Literally exactly what you are looking for. It's right on the screen unless someone changed it to remove it (and I don't even think you can).
 

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Some other Tesla forum (TMC?), but around here somewhere too on a not relevantly labelled thread. Tesla patent even mentions using the cabin blower motor and compressor motor in "lossy" mode to create heat. Same effect of using some software controlled waveform manipulation in the motor controllers.
I remember someone on this forum someone brought up the idea. I disagreed with their theory. Or, more correctly doubted that was the route Tesla took. I'm more curious about more factual based content that suggests Tesla changes the transistor firing pattern to make the inverter/motor run inefficient to make heat. You mentioned a utube?
 

JBee

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Its in the patent as well.




Theres a few parts, can't remember which one it was in.
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