Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register
  • Tesla AI Day watch party is live right now. You can watch the stream on YouTube.

Battery heating when Supercharging

Leeroy

2021 SR+
May 26, 2021
376
226
Victoria
Charged yesterday at the Mornington supercharger, didn’t take long to navigate there so minimal preheating. When I arrived the battery bacon icon displayed on the app after I plugged in. Charge Speed varied, 80kw to max 94kw from 20% soc.
What I’m wondering was the 5kw variation (96kw vs 91kw) from the car vs the app in the pics below. It would make sense to have a difference if the battery heater was running but for the ENTIRE session I didn’t hear the stators AT ALL. So it begs the question, what is heating the battery if the stators aren’t?
Im hoping 5kw isn’t the loss from the supercharger metering to what goes into the battery! That gets expensive.
12E0B082-B03C-4F50-93D4-9BD8256B7A7F.jpeg 823F32E0-52BB-488D-A6D5-6222CCE83840.png
 
My only comment would be "don't sweat the small stuff".

EV's provide more car related data than ever before, and getting hung up on it can lead to "paralysis by analysis".

For example, for many tesla owners, it's the first car they've owned that provides realtime tyre pressures, and as a result we see so many queries online from owners like "OMG my left rear tyre is 1 psi lower than the others, what to do?".

WIth their previous car, they wouldn't have had a clue.

If the car and app wasn't showing you the data of 96kw vs 91kw, you wouldn't even have anything to worry about.
 
Interesting! I charged at a new JOLT yesterday and the charger said 22.8kW while the car said 12kW. I checked and 5.8kW was going into stator heating. No climate control. Just the screen (~300W) and the coolant/heating circulating pump. So, 5kW LOST somewhere. Seems similar!
Scan my Tesla and car both said (and I calculated too) 12kW (voltage x current).
 

Leeroy

2021 SR+
May 26, 2021
376
226
Victoria
Interesting! I charged at a new JOLT yesterday and the charger said 22.8kW while the car said 12kW. I checked and 5.8kW was going into stator heating. No climate control. Just the screen (~300W) and the coolant/heating circulating pump. So, 5kW LOST somewhere. Seems similar!
Scan my Tesla and car both said (and I calculated too) 12kW (voltage x current).
Where you getting the howl from the motor? I could hear the fans running up front but nothing from the back at all.
 
Where you getting the howl from the motor?
I don't know what that sounds like. Not sure I have heard it or I have not known what it is. I could hear a quiet motor noise which sounded like coolant pump/s. But there was nothing noisy at all. 5kW is a lot of juice to "go missing". I saw on a video that in Norway, the DC chargers use the power going to the car, not into the charger. So there, the provider incurs the cost of inefficiency.

I have charged around 6 other times at JOLTs and this is the first time I have seen energy go missing. But then, it is a different looking charger to the earlier ones and on top of that, my car has had about 5 software updates since the previous JOLT use.

I was mainly struck by the fact that we each have "lost" about 5kW on two different chargers.
 
I didn’t hear the stators AT ALL.
Keep in mind. You have a heat pump car, the stators don't have to be active when heating. In my experience the stators only kick in when it needs max heat quickly. The stators stop heating after the battery coolant inlet temp gets about ~130F and then it will kick to heat pump heating only to maintain the inlet temp until the battery get all the way up to temp. The heat pump alone can take ~4.5kw and about 500watts for computers and coolant pumps. Stators take 3.5kw (rear) and 2.5kw (front). So when max heating its about 10kw "phantom" losses.
 
In my experience the stators only kick in when it needs max heat quickly.
Interesting, I did not know that. In my JOLT case, the temperatures definitely were lower than previous times (winter is coming, early morning, short trip....) and I was losing 10kW in total. 22kW DC charging is definitely way less efficient than 100+kW charging. I think I'll stick with AC around town unless the battery is over 40degC,
 
22kW DC charging
Yeah lower wattage DC kinda sucks. I only get like 33-34kw on a 50kw (125amp) DCFC, while the charger says its outputting 43-44kw. But yeah heat pumps are great. Even though they are only drawing ~4kw they are "producing"/pumping more like 8-9kw of heat plus the ~6-7kw from the stators. Quite a lot of heat. But thats why the stators kick out when the packs almost warmed up, as the heat pump can "produce" more heat than the ~99% efficiency of the stators, thus more energy going into the pack.

Tesla also treat pack heating the same for all DCFC charging. IMHO the pack doesn't need to be 50c+ to do <50kw charging. 40c is probably plenty. Hopefully they'll update things in the future or give us more control over pack heating as it only preconditions automatically when navigating to a Supercharger.
 
5kw variation (96kw vs 91kw)
As you correctly said it is the “Charge Speed” - the rate at which electrons are travelling from charger to car. But it is not the total electrons added to the car which is in kWh not kW

Charge speed will vary according to various factors - battery voltage, temperature is another.
You ultimately only get charged for Charge added which is the “+14kWh”. (Though EV users can be billed for the privilege of using a higher charge speed in some cases)

So to confirm you pay for kWh not kW.
Some do pay for high kW charging rate as opposed to slow kW charging (time is money)

From what I’m reading in these forums, Instead of range anxiety, the anxiety is morphed into kWh anxiety, psi anxiety, battery longevity anxiety etc etc😀
 
I don't know what that sounds like. Not sure I have heard it or I have not known what it is. I could hear a quiet motor noise which sounded like coolant pump/s. But there was nothing noisy at all. 5kW is a lot of juice to "go missing". I saw on a video that in Norway, the DC chargers use the power going to the car, not into the charger. So there, the provider incurs the cost of inefficiency.

I have charged around 6 other times at JOLTs and this is the first time I have seen energy go missing. But then, it is a different looking charger to the earlier ones and on top of that, my car has had about 5 software updates since the previous JOLT use.

I was mainly struck by the fact that we each have "lost" about 5kW on two different chargers.
I had some stator heating this morning so took a vid for you. It’s quite loud standing next to the car!

Stator heating
 

moa999

2020 3 SR+ MSM
Mar 4, 2020
2,144
2,179
Sydney, AUS
Some discussion in the Jolt thread about heating on DC in various models.

Can be up to 11kW
3kW rear motor
3kW front motor (only LR/P)
5kW heat pump (only 2021+)

That said the more recent cars are seemingly at temperature much quicker, so the total energy used is probably the same (maybe lower given efficiency of heat pump using air temp)

And if you've preheated to a supercharger, yes you get a higher charging rate, but you've also arrived at a lower SoC
 
Last edited:
  • Like
  • Informative
Reactions: Ted H and Leeroy
My SR is definitely favouring the heat pump over the stator compared to this time last year. I didn’t even know it could do just the heat pump until this thread.
Previously I’d get the stator for a solid 30 mins until climate switched itself off, now only up to about 15 mins.
 

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top