*Coolness* Anybody else pre-conditioning the cabin to stay cool?

[Saguarojoe]

I think it’s super awesome. It’s also available for some ICE cars. A friend of mine has a Kia SUV that he can remotely start the engine and the AC from his cell phone.

The Tesla’s really awesome unique feature for me is the automatic cabin cooling to prevent the interior to heat up excessively. Even if I forget to use my app to precondition the cabin, the seats are never scorching.

I used to live in Maryland. Illegal to leave your car engine on. Got a ticket to prove it. Wonder how the cops will react to a Tesla with the A/C running

 

[birjman]

I do this in central FL so that I can get the mandatory vinegar smell flush out of way before I get into the car. 7/10 times it still smells like feet anyways for my entire drive home from work. (Yes, I make sure to to have re-circulate turned off.)

 

[darth_vad3r]

I'm in Atlanta, the car cools down so quickly with the electric AC that I don't worry about it.

Preconditioning is a great way to avoid sitting on hot seats that stay hot with your body on them even as the cabin does quickly cool.

You should try it.

Definitely one of my favourite features of an EV (pretty sure they can all/mostly do this since there’s no ICE engine to fire up to wastefully cool down the cabin while burning dead dinosaurs)

 

[darth_vad3r]

I was able to dig in a little more info from the API. First, I looked up the historic temperature and 8/17/18 had a high temperature of 88° so obviously the "Outside Temp" is affected by being parked under the sun.

Right before conditioning started, the API showed 1.33 hours for "time to full charge." Once conditioning started, the time left jumped to 16 hours, settled down to about 5-7 hours remaining while cooling and went down to 2-2½ hours once car reached set temperature of 70°.

With the AC off, the car was charging around 5.2 kW. While cooling, it looks like the A/C was consuming 4-5 kW and reduced to about 2 kW once reached set temperature.

The numbers look a little high but the car was parked under the sun in 88° weather so car would be working harder to keep the inside temp at 70°.

If you are looking at the API, look at charge_state.charge_rate which shows the rate of charge being added in mi/hr. You can see what that is with no A/C, then compare to max A/C and maintaining A/C to calculate rough kW draw of A/C.

I’ve never seen it anywhere near 5 kW for A/C. Heat? No problem. I think maybe you have an error in your calculation or methodology.

 

[StealthP3D]

Wonder how the cops will react to a Tesla with the A/C running

I would assume they wouldn't think twice about it. Because the car would not have a running engine!

The National Safety Council says, on average, 38 children die in hot cars every year in the US:

Hot Car Deaths - Injury Facts

Texas and Florida are the biggest contributors.

 

[LJ32]

I have to admit, living in California I never had a use for pre-conditioning but after multiple trips to desert SW with temps during the day of 115+ and evening temps 95+, I learned to love Tesla's climate control options. I have taken both my M3P+ and MX 100D on several desert trips. First feature I turned on was "cabin overheat protection" which is a great feature. I also used the app to activate normal climate settings 10mins before coming back to the vehicle. During full day travel with a cooler in the back hatch of the MX, I also left climate on and set to 81. Best test was return trip home which was 10-hours, multiple stops, and temperatures exceeding 110 with full sun the whole trip. After getting home, cooler only had about a 5% ice melt. True EV advantage and with Tesla long range batteries, a true competitive advantage. I saw no noticeable impact on mileage range for any of these trips.

 

[AlanSubie4Life]

I was just wondering about that yesterday. I wonder at what point it becomes more efficient to turn it off and just pre-cool for three minutes before arriving back to your car?

I would guess that for all intents and purposes, it is always more efficient to turn it off when you are not in the car. Leaving it on is virtually guaranteed to be more energy intensive. Heat loss to the environment increases with the difference in temperature. In addition, the system is likely more efficient when it is operating at maximum speed.

 

[StealthP3D]

I would guess that for all intents and purposes, it is always more efficient to turn it off when you are not in the car. Leaving it on is virtually guaranteed to be more energy intensive. Heat loss to the environment increases with the difference in temperature. In addition, the system is likely more efficient when it is operating at maximum speed.

Minisplit heat pumps are very similar to the Model 3 A/C and they typically reach peak efficiency around 1/3 of full capacity. The common wisdom is it might not be worth it to shut them off at night if they are going to have to work harder to reach their set temperature the next day.

 

[AlanSubie4Life]

Minisplit heat pumps are very similar to the Model 3 A/C and they typically reach peak efficiency around 1/3 of full capacity. The common wisdom is it might not be worth it to shut them off at night if they are going to have to work harder to reach their set temperature the next day.

Maybe for mini-split. I seriously doubt any of this common wisdom though TBH (not on efficiency grounds but on energy savings grounds). You’d have to see what the efficiency curve of the the Model 3 is obviously. But in any case for the temps of interest here where you’d want to leave the AC running, my guess is that the AC would be running at greater than 1/3 capacity. And obviously the efficiency is only part of the issue - just keeping the car cool when it doesn’t need to be (kind of like keeping your house cool) is going to be pretty wasteful of energy (0% efficient).

But if I were trying to minimize my energy use I’d just turn it off.

 

[StealthP3D]

Maybe for mini-split. I seriously doubt any of this common wisdom though TBH (not on efficiency grounds but on energy savings grounds). You’d have to see what the efficiency curve of the the Model 3 is obviously. But in any case for the temps of interest here where you’d want to leave the AC running, my guess is that the AC would be running at greater than 1/3 capacity. And obviously the efficiency is only part of the issue - just keeping the car cool when it doesn’t need to be (kind of like keeping your house cool) is going to be pretty wasteful of energy (0% efficient).

But if I were trying to minimize my energy use I’d just turn it off.

Obviously, when it's off it's not using any energy at all. But we are discussing those times when you will only be gone a short while. It may not pay to let the system depressurize and for the system temperatures to equalize only to come back and crank it on high to get back to where you were three minutes ago. It would likely be more efficient to just let it continue to loaf along for those few minutes. One reason why this system is so much more efficient than a traditional auto A/C using an electromagnetic clutch to cycle on/off is precisely because it doesn't need to cycle on/off -- it just goes into a very gentle "loaf" state.

Of course, there is not one absolute answer as to the exact amount of time where it is better to just leave it on since it will vary with things like the inside/outside temperature differential, the set fan speed, recirculate setting, sun or shade, etc.

 

[AlanSubie4Life]

Obviously, when it's off it's not using any energy at all. But we are discussing those times when you will only be gone a short while. It may not pay to let the system depressurize and for the system temperatures to equalize only to come back and crank it on high to get back to where you were three minutes ago. It would likely be more efficient to just let it continue to loaf along for those few minutes. One reason why this system is so much more efficient than a traditional auto A/C using an electromagnetic clutch to cycle on/off is precisely because it doesn't need to cycle on/off -- it just goes into a very gentle "loaf" state.

Of course, there is not one absolute answer as to the exact amount of time where it is better to just leave it on since it will vary with things like the inside/outside temperature differential, the set fan speed, recirculate setting, sun or shade, etc.

Sure. In the end, if you want to know the answer, it is relatively easy to emulate a couple situations and measure. (You have to stay in drive.) Just do a 10-minute period with start point and end point at the same temp, and then another 10-minute period where you start at same temp, turn off the AC for three minutes and then end at the same temp. Or whatever.

Anyway, for the situations where it might result in some savings, the savings would be small enough that I am not sure it matters, though.

In any case, coming back to a cool car is great. Used it last week when it was oppressively warm here in SD.

 

[XLR82XS]

I used to live in Maryland. Illegal to leave your car engine on. Got a ticket to prove it. Wonder how the cops will react to a Tesla with the A/C running

Probably not do anything since there is no ICE running. I would assume most cops/first responders are now well aware of the vast amounts of Teslas/electric vehicles out there. I'm sure there will be some that will be stumped if coming across one "idling".

 

[StealthP3D]

Sure. In the end, if you want to know the answer, it is relatively easy to emulate a couple situations and measure. (You have to stay in drive.) Just do a 10-minute period with start point and end point at the same temp, and then another 10-minute period where you start at same temp, turn off the AC for three minutes and then end at the same temp. Or whatever.

Anyway, for the situations where it might result in some savings, the savings would be small enough that I am not sure it matters, though.

In any case, coming back to a cool car is great. Used it last week when it was oppressively warm here in SD.

You can say that again! Sitting in the nice cool Model 3 is making me consider a mini-split heat pump for my den where we spend most of our time. It's an extension off the south side of the house so it gets hit by the sun on three walls throughout the day and is pretty warm by 6 pm with the way the weather has been. The common wisdom here in the Pacific Northwest was that air conditioning was not needed with the cool air coming off the ocean but I think global warming is changing that!

I think I'll go sit in my Model 3 with the A/C running for some relief. It's got to be more efficient to cool the car's cabin than an entire room!