Does Chill mode increase efficiency? Surprisingly, Tesla says yes

Does Chill mode increase efficiency?

This question seems to come up in Tesla circles every so often, and the conventional answer is "no, if you drive exactly the same speeds then acceleration mode does not impact efficiency".

But Tesla has some interesting notes in the manual:

If your vehicle is equipped with a heat pump (to determine if your vehicle has a heat pump, touch Controls > Software > Additional Vehicle Information), you can improve the efficiency of the cabin heating by reducing your selected acceleration mode. This allows the heat pump system to take more heat from the Battery to efficiently heat the cabin, instead of maintaining the Battery's ability to provide peak acceleration performance.

So in weather cold enough to use cabin heating apparently yes it can improve efficiency.

Link to the section for Model 3 (it also exists for S and presumably any heat bump vehicle).

"Tesla Model 3 | E-Cannonball 2018" by JayUny is licensed under CC BY-SA 2.0.
Admin note: Image added for Blog Feed thumbnail

 

[DrGriz]

That is completely irrelevant to the discussion of how chill mode or sport mode behave.

If at temperatures below 10°C (my car has not been driven in higher temperatures for the last 4.5 months) chill mode takes less energy from the battery to heat the cabin (not sure it's necessary to heat the cabin in that way above that point, especially on a sunny day) then it has everything to do with range and efficiency.

Seriously, I might not have to pull energy from the battery to heat the cabin at outside temperatures above 50° F. Which is what we are talking about.

In that case, of course chill mode is more efficient.

 

[voldar]

10°C is not cold. If you think so, "you haven't driven very far."

He was talking about battery temperature, not outside temperature. And yes, when the car is plugged in, the battery is kept at around 10C.

And I agree with you, I never used Chill mode in cold temperature (below freezing temperature). When I used it, it was less efficient than using Standard mode in my 2023 M3 LR AWD.

 

[sleepydoc]

That is completely irrelevant to the discussion of how chill mode or sport mode behave.

Hardly - ambient temperatures affect battery temperature and 10º is not cold enough to require significant warming of the battery. @DrGriz 's comment is spot on.

 

[David99]

The discussion is about if we can see a difference in battery temperature depending on weather the car is driven in chill or sport mode. This is the claim the manual makes. I have access to the battery temperature though CAN bus data and shared my experiences from actual driving in both modes and monitoring battery temperature. I don't see a difference in the scenarios I was able to test. Commenting that 10 C isn't "cold" is just random and doesn't contradict nor conform any of the findings, nor does it add a data point. It's just a random comment about what someone thinks "cold" is or not.

 

[DrGriz]

The discussion is about if we can see a difference in battery temperature depending on weather the car is driven in chill or sport mode. This is the claim the manual makes. I have access to the battery temperature though CAN bus data and shared my experiences from actual driving in both modes and monitoring battery temperature. I don't see a difference in the scenarios I was able to test. Commenting that 10 C isn't "cold" is just random and doesn't contradict nor conform any of the findings, nor does it add a data point. It's just a random comment about what someone thinks "cold" is or not.

You tested at one "random" temperature. Let's see your repeated results at 100 different battery temperatures. Either that, or I will accept what the Tesla engineers have to say over your isolated anecdotal observation.

 

[David99]

You tested at one "random" temperature. Let's see your results at 100 different battery temperatures. Either that, or I will accept what the Tesla engineers have to say over your isolated report.

I never said my tests are conclusive. Let me see what you have contributed so far from your tests, please. I still don't understand what "10 C isn't cold" and "if you believe that you haven't driven far" has added to finding an answer to the discussion.

 

[DrGriz]

I never said my tests are conclusive. Let me see what you have contributed so far from your tests, please. I still don't understand what "10 C isn't cold" and "if you believe that you haven't driven far" has added to finding an answer to the discussion.

Just about as much as your random "test" adds.

 

[David99]

Just about as much as your random "test" adds.

Show me your tests that are more helpful, please.

 

[DrGriz]

Show me your tests that are more helpful, please.

I think you are confused. I made no "tests." Nor did I make any claims. That was you.

It's perfectly logical to me that there may be conditions where it takes energy to maintain battery temperature to allow for faster acceleration which ultimately results in range loss and therefore efficiency loss. That's the topic of the thread.

If you do your test when the heat pump isn't scavenging heat from the battery to warm the cabin, then it stands to reason you won't see any difference in temperature of the battery or efficiency. The manual is talking about the situation when the heat pump is pulling heat to heat the cabin.

I don't know why you think your observation negates that. It means nothing. So we are left with debating the definition of "cold" which you brought up.

 

[Spinkick]

At a certain point when its cold enough the heat pump cant pull heat from ambient air. I'm guessing 10C is probably still warm enough where the car doesnt have to spend time heating the battery. I wonder what the temperature cut off is for that? It would be cool to get that scanner in a colder environment, or even cold soak the battery and see what temp the battery gets conditioned to depending on the two different drive modes (sport or chill)

 

[voldar]

At a certain point when its cold enough the heat pump cant pull heat from ambient air.

The Tesla heat-pump gets the heat from 14 places, not only from the ambient air. It's not "I can't provide the heat from the air, I'll try to get it from the rotors".
From my experience, when driving in cold weather, the battery is always kept at around 7-11C when using the Standard mode. I once drove in Chill mode and the temperature of the battery was around 5C-9C. This tells me to never drive in Chill mode in cold weather. Why ? Because although the heat-pump will scavenge heat from the battery (thus less electrons used from the battery), it does makes it perform worse, keeping it colder. So, in the end, what you gain from driving in Chill mode, you lose in the battery efficiency. Don't forget, the heat-pump scavenge the battery heat also in Standard mode, just not that much.

Chill mode for a Tesla with a heat-pump isn't good in cold weather, IMO. It is good in above freezing temperatures.

 

[DrGriz]

The Tesla heat-pump gets the heat from 14 places, not only from the ambient air. It's not "I can't provide the heat from the air, I'll try to get it from the rotors".
From my experience, when driving in cold weather, the battery is always kept at around 7-11C when using the Standard mode. I once drove in Chill mode and the temperature of the battery was around 5C-9C. This tells me to never drive in Chill mode in cold weather. Why ? Because although the heat-pump will scavenge heat from the battery (thus less electrons used from the battery), it does makes it perform worse, keeping it colder. So, in the end, what you gain from driving in Chill mode, you lose in the battery efficiency. Don't forget, the heat-pump scavenge the battery heat also in Standard mode, just not that much.

Chill mode for a Tesla with a heat-pump isn't good in cold weather, IMO. It is good in above freezing temperatures.

Very useful information. It would be awesome to have more data points.

And, the manual says chill improves "heating" efficiency, not "driving efficiency," so your observation is in line with what they are saying. It may also be that the net efficiency is better with chill. That's how I read the manual's statement.

 

[sleepydoc]

The Tesla heat-pump gets the heat from 14 places, not only from the ambient air. It's not "I can't provide the heat from the air, I'll try to get it from the rotors".
From my experience, when driving in cold weather, the battery is always kept at around 7-11C when using the Standard mode. I once drove in Chill mode and the temperature of the battery was around 5C-9C. This tells me to never drive in Chill mode in cold weather. Why ? Because although the heat-pump will scavenge heat from the battery (thus less electrons used from the battery), it does makes it perform worse, keeping it colder. So, in the end, what you gain from driving in Chill mode, you lose in the battery efficiency. Don't forget, the heat-pump scavenge the battery heat also in Standard mode, just not that much.

Chill mode for a Tesla with a heat-pump isn't good in cold weather, IMO. It is good in above freezing temperatures.

That’s not totally accurate. The heat pump can take heat from and deliver it to multiple places including the ambient air, the battery, the motors and the cabin. At colder temperatures it has to work harder to get heat from the ambient air, but 0-10° c is well within its capabilities.

At colder temps it doesn’t ’take electrons’ from the battery per se and you don’t lose battery efficiency or capacity. The energy stored in the battery is the same at 0° as it is at 60°. What changes is how rapidly you can access that energy. Current is produced via a chemical reaction and that reaction happens slower at lower temperatures. Similarly, the battery must charge slower at lower temperatures. That is why the car must condition the battery to supercharge and also why regenerative braking is limited when the battery is too cold.

By design, chill mode limits acceleration and thus limits the maximum current draw from the battery meaning there are different temperature requirements for the battery. What this means in terms of overall performance and efficiency depends on a lot of factors (ambient temp, cabin heating, cooling, etc)

 

[voldar]

0-10° c is well within its capabilities.

Not sure from where you guys got the 10C temperature ? I imagine you are talking about the message from @David99 who was talking about the battery temperature. Which has nothing to do with outside temperature.
I also said in another post that no matter the temperature outside the car, while plugged, is keeping the battery temperature at around 10C (even when preconditioning is active). It doesn't heat the battery above 10C. Only when you started the process of preconditioning of the battery to charge, the battery is heated to about 36C and it takes about 1% of the battery every 5 minutes of preconditioning.

While driving in above freezing weather (3C) for about 70 km, the battery kept a temperature, as registered in the Service mode once I arrived home, of :
- Min : 12.5 C
- Max : 17.5 C
When driving in bellow freezing temperatures (-10C) for about 45 km, the battery temperature went down :
- Min : 2.25 C
- Max : 10.25 C
In this test I didn't use the Chill mode. When I used the Chill mode, the Max temperature was 7C.

So, IMO, driving in Chill mode in temperatures above the freezing point, it is ok. Driving in Chill mode in temperatures below freezing, I wouldn't recommend, if you want to have the best efficiency.

I posted here the info I got myself when I tested the preconditioning to charge. Unfortunately the site ****ed up the pictures (just realized today).

 

[voldar]

It may also be that the net efficiency is better with chill. That's how I read the manual's statement.

When I drove in Chill, I always got a worse efficiency than when I was driving in Standard mode. Maybe because I wasn't used to the sluggish Chill mode and was pushing more the acceleration pedal. Either way, it is not a problem, you may be right. I don't like Chill mode. In my Bolt EV I had standard mode and Sport mode. I am used to the acceleration of an EV and I can feather it to have a smooth like butter take off, don't need Chill mode to stop jerking the car.

 

[sleepydoc]

When I drove in Chill, I always got a worse efficiency than when I was driving in Standard mode. Maybe because I wasn't used to the sluggish Chill mode and was pushing more the acceleration pedal. Either way, it is not a problem, you may be right. I don't like Chill mode. In my Bolt EV I had standard mode and Sport mode. I am used to the acceleration of an EV and I can feather it to have a smooth like butter take off, don't need Chill mode to stop jerking the car.

If you’re accelerating hard enough that you notice the difference between chill and standard modes then efficiency isn’t your primary concern.

 

[sleepydoc]

Not sure from where you guys got the 10C temperature ? I imagine you are talking about the message from @David99 who was talking about the battery temperature. Which has nothing to do with outside temperature.

Everyone seems focused on 5-10º temps so that's what I referenced.

So, IMO, driving in Chill mode in temperatures above the freezing point, it is ok. Driving in Chill mode in temperatures below freezing, I wouldn't recommend, if you want to have the best efficiency.

How do you arrive at that conclusion? You've already posted that it takes significant energy to heat the battery. Why would you want to heat it more than necessary?

 

[stopcrazypp]

That’s not totally accurate. The heat pump can take heat from and deliver it to multiple places including the ambient air, the battery, the motors and the cabin. At colder temperatures it has to work harder to get heat from the ambient air, but 0-10° c is well within its capabilities.

At colder temps it doesn’t ’take electrons’ from the battery per se and you don’t lose battery efficiency or capacity.

Actually you do. Pretty much all lithium-ion battery cells have higher internal resistance at lower temperatures, which means there is a real resistive efficiency loss when the battery is operating in colder weather.

So you really have to balance the energy consumption from heating/maintaining a battery temp, versus the losses from higher internal resistance.

The energy stored in the battery is the same at 0° as it is at 60°. What changes is how rapidly you can access that energy. Current is produced via a chemical reaction and that reaction happens slower at lower temperatures. Similarly, the battery must charge slower at lower temperatures. That is why the car must condition the battery to supercharge and also why regenerative braking is limited when the battery is too cold.

By design, chill mode limits acceleration and thus limits the maximum current draw from the battery meaning there are different temperature requirements for the battery. What this means in terms of overall performance and efficiency depends on a lot of factors (ambient temp, cabin heating, cooling, etc)

 

[voldar]

How do you arrive at that conclusion? You've already posted that it takes significant energy to heat the battery. Why would you want to heat it more than necessary?

Because the battery is only heated to 36C when preparing to charge.
For the rest of the time, the battery, while driving, is kept to a very low temperature in cold weather (5C to 10C battery temperature, sometimes even lower, but above 0C). And let me tell you, when your battery is at 2C (Chill mode) and you want to bring it to 36C for an optimal charge, you spend a lot more energy than bringing it from 10C to 36C. But you are free to do whatever you like.

 

[Spinkick]

The Tesla heat-pump gets the heat from 14 places, not only from the ambient air. It's not "I can't provide the heat from the air, I'll try to get it from the rotors".
From my experience, when driving in cold weather, the battery is always kept at around 7-11C when using the Standard mode. I once drove in Chill mode and the temperature of the battery was around 5C-9C. This tells me to never drive in Chill mode in cold weather. Why ? Because although the heat-pump will scavenge heat from the battery (thus less electrons used from the battery), it does makes it perform worse, keeping it colder. So, in the end, what you gain from driving in Chill mode, you lose in the battery efficiency. Don't forget, the heat-pump scavenge the battery heat also in Standard mode, just not that much.

Chill mode for a Tesla with a heat-pump isn't good in cold weather, IMO. It is good in above freezing temperatures.

I'd be interested to understand why the Engineers designed it that way. It seems like if it was net less efficient to drive in chill mode in very cold temps, at the very least the energy app would say so. Then again, the energy app is also not saying to use chill mode when its very cold.