Did you know the 3 heats the battery (actively) constantly while DC charging at any speed or temp?

[Gauss Guzzler]

There must be some balance here since charging too fast at low battery temps is not good for the battery as well, but it sure seems like the super-simple logic below is used:

IF (DC_charging AND Battery_temp < active_heating_temp) THEN
heat_pack_100_percent()
ENDIF

Yeah, you're probably right but what difference does it make? Bjorn did the most ridiculous extreme corner case imaginable and still it didn't even make any meaningful difference.

- He took an obsolete car with no octovalve,
- Cold soaked it to arctic temperatures (notice it was -1C *inside* the garage - how cold was the car after being outside?),
- Ran it in track mode out there on the tundra to super-cool the battery,
- Then pulled the ice-covered car into this garage and connected it to the most ridiculous charger anyone has ever attempted to YouTube charge a Tesla with: 15kW DC! He even talked about how silly it was and pointed out the proper outlets on the wall that he would use if he wasn't YouTubing.
- Then he failed to mention that cold charging degrades the battery more than warm charging, even if the difference may be much smaller at 15kW.
- And forgot that he had done an entire video about the proportional battery heating that occurs even under *AC* charging as needed to reduce battery degradation, noting that Tesla's reduced cobalt chemistry is even more sensitive to cold charging than most.
- And also forgot that in that very video, he had discovered that even his iPhone refused to charge in order to protect its battery from cold charging damage.

And after all that absurdity what happened? Well, the car used 7kW to heat the battery for the first 33 minutes, "consuming" a total of 4kWh. So yeah, in the most extreme worst-case contrived scenario, you might find that a full charge uses about 5% more energy ($0.40) to prolong the life of your $16,000 battery. Mmmm, gasp.

Tesla has some of the dumbest software developers in the industry (V11), but there's no indication that any of those morons are on the battery team.

 

[drtimhill]

Tesla has some of the dumbest software developers in the industry (V11), but there's no indication that any of those morons are on the battery team.

These are UX guys, not software developers .. different breed. UX guys are people who cannot tell the difference between "different" and "better".

 

[rrolsbe]

Yeah, you're probably right but what difference does it make? Bjorn did the most ridiculous extreme corner case imaginable and still it didn't even make any meaningful difference.

- He took an obsolete car with no octovalve,
- Cold soaked it to arctic temperatures (notice it was -1C *inside* the garage - how cold was the car after being outside?),
- Ran it in track mode out there on the tundra to super-cool the battery,
- Then pulled the ice-covered car into this garage and connected it to the most ridiculous charger anyone has ever attempted to YouTube charge a Tesla with: 15kW DC! He even talked about how silly it was and pointed out the proper outlets on the wall that he would use if he wasn't YouTubing.
- Then he failed to mention that cold charging degrades the battery more than warm charging, even if the difference may be much smaller at 15kW.
- And forgot that he had done an entire video about the proportional battery heating that occurs even under *AC* charging as needed to reduce battery degradation, noting that Tesla's reduced cobalt chemistry is even more sensitive to cold charging than most.
- And also forgot that in that very video, he had discovered that even his iPhone refused to charge in order to protect its battery from cold charging damage.

And after all that absurdity what happened? Well, the car used 7kW to heat the battery for the first 33 minutes, "consuming" a total of 4kWh. So yeah, in the most extreme worst-case contrived scenario, you might find that a full charge uses about 5% more energy ($0.40) to prolong the life of your $16,000 battery. Mmmm, gasp.

Tesla has some of the dumbest software developers in the industry (V11), but there's no indication that any of those morons are on the battery team.

I do not necessarily disagree with most of your post observations, however, follows are my thoughts. When Tesla Engineers eek out more efficiency while the car is being driven, most people applaud the effort; however, it seems some of those same people poo poo when someone suggests Tesla could also improve the efficiency of the vehicle while is not being driven. If my 2018 Model 3 is not driven often or if the miles driven are low when it is driven, the overhead is a large portion of the energy usage. The energy consumption overhead while not driving or charging might seem insignificant cost/charge time wise but when Tesla has several million cars on the road the better overall efficiency of their vehicles could save a considerable amount of energy/owner time.

I can charge my wife's hybrid ,park it for up to three weeks and the traction battery will not use any energy. I know her hybrid is a radically different beast but parking for an extended period of time is not even a concern. Not sure how other EV's compare to Tesla regarding none driving power usage overhead??

If someone regularly home charges their Tesla at 240V/48A AC and minimal battery heating is required, charging via DC should be able to deliver at least 11kW to the traction battery under the exact same conditions (only elevate the cell temps as needed to allow charging at higher DC power levels). High power DC charging warms the cells much quicker than the 4kW power available from my rear drive Model 3 stator motor windings . Why would Tesla not be concerned about battery longevity when AC charging the battery at lower temps than delivering the equivalent DC power? After all, most owners would most likely be AC charging at home way more often than DC charging. After all, the onboard AC charger delivers rectified DC power to the traction battery the same way the DC sourced path does. Bottom line, I believe there is considerable low hanging efficiency fruit that could be reaped by Tesla outside of the driving mode. As an Engineer, I'am sure improving driving efficiency is more satisfying.

 

[Gauss Guzzler]

Tesla's algorithm always seeks to balance efficiency & convenience with cell degradation, whether it's AC or DC, and it does so in a complex nonlinear manner that is clearly intended to be thoughtfully optimized.

Bjorn's video shows that even when charging from home on a low power *AC* charger, the car diverts some significant portion of the charge current to heat the battery, varies that percentage nonlinearly according to the available charge current, and even pauses the charge multiple times during the session to reheat the battery with full power if needed.

It's strange that Bjorn didn't seem to understand the point of his own video. Even when he had to interrupt himself mid-video to improvise an external battery heater so that he could charge his iPhone for the very same reason. He seemed fully aware, accepting of, and even impressed by his iPhone's intelligent battery management but concluded that the Tesla was doing it unnecessarily and should provide an option for the user to disable the protection.

 

[Rocky_H]

You are entirely missing the point several times. Having to heat the battery to some level when it is too cold to charge is a given in ALL circumstances, regardless of whether it's AC or DC.

You made several irrelevant points about how dumb it was how cold the car had been.

You made this weird and also irrelevant observation:

Then he failed to mention that cold charging degrades the battery more than warm charging, even if the difference may be much smaller at 15kW.

The cars always prevent charging below the harmful temperature threshold, no matter the temperature or charging source. So you're not making a point with that.

And forgot that he had done an entire video about the proportional battery heating that occurs even under *AC* charging as needed to reduce battery degradation, noting that Tesla's reduced cobalt chemistry is even more sensitive to cold charging than most.

Also irrelevant, as mentioned above. It will of course warm as much as needed to do charging.

And also forgot that in that very video, he had discovered that even his iPhone refused to charge in order to protect its battery from cold charging damage.

Of course--so does my Zero motorcycle, which doesn't have any method for battery heating, just like a phone doesn't. What does that have to do with anything?

Tesla's algorithm always seeks to balance efficiency & convenience with cell degradation, whether it's AC or DC, and it does so in a complex nonlinear manner that is clearly intended to be thoughtfully optimized.

We wish.

Bjorn's video shows that even when charging from home on a low power *AC* charger, the car diverts some significant portion of the charge current to heat the battery, varies that percentage nonlinearly according to the available charge current, and even pauses the charge multiple times during the session to reheat the battery with full power if needed.

It's strange that Bjorn didn't seem to understand the point of his own video. Even when he had to interrupt himself mid-video to improvise an external battery heater so that he could charge his iPhone for the very same reason. He seemed fully aware, accepting of, and even impressed by his iPhone's intelligent battery management but concluded that the Tesla was doing it unnecessarily and should provide an option for the user to disable the protection.

*sigh* And all of this is entirely still missing the point. This is about APPROPRIATE heating. The cars are set to do appropriate heating when AC charging. That is not what this thread is about. This thread is about how there is sensible logic when it is using an AC source, and it handles that very intelligently and sensibly and efficiently, heating only as much as is needed to deal with the real temperature conditions.

But this thread is about how it throws its brain out the window when connected to a DC source and just uses:
If source == DC, HEATTHEEVERLOVINGHELLOUTOFTHEBATTERYFOREVER

 

[diamond.g]

You are entirely missing the point several times. Having to heat the battery to some level when it is too cold to charge is a given in ALL circumstances, regardless of whether it's AC or DC.

You made several irrelevant points about how dumb it was how cold the car had been.

You made this weird and also irrelevant observation:

The cars always prevent charging below the harmful temperature threshold, no matter the temperature or charging source. So you're not making a point with that.

Also irrelevant, as mentioned above. It will of course warm as much as needed to do charging.

Of course--so does my Zero motorcycle, which doesn't have any method for battery heating, just like a phone doesn't. What does that have to do with anything?

We wish.

*sigh* And all of this is entirely still missing the point. This is about APPROPRIATE heating. The cars are set to do appropriate heating when AC charging. That is not what this thread is about. This thread is about how there is sensible logic when it is using an AC source, and it handles that very intelligently and sensibly and efficiently, heating only as much as is needed to deal with the real temperature conditions.

But this thread is about how it throws its brain out the window when connected to a DC source and just uses:
If source == DC, HEATTHEEVERLOVINGHELLOUTOFTHEBATTERYFOREVER

It is an interesting catch 22 Tesla has bought on itself. The 3 used to not heat the battery at all when DC charging (we called it permanent range mode) when it was first released. Folks (rightfully) complained about how long fast charging took (in the cold), so they updated the charging system (and added the whole preconditioning feature). They decided that if you are using fast charging you want the charge to be fast and the battery needs to be hot to make the fast charge happen. Internally I don't think Tesla took slower than 72kW chargers into account when doing all this so we get hit with really inefficient low speed DC charging as a result.

I wonder if they could treat under 72kW charging like AC charging and just slooooowly ramp from 11kW to max rate of the charger once the battery is sufficiently warmed, or are people going to complain about how slow the ramp is (still).

 

[SteelClouds]

I enjoy reading all this detailed analysis.. good stuff.. but I temper it with this.. does my battery degrade? why yes, it does every single time I use it. Just like an ICE degrades every time it's used. Does it degrade a lot? not so you would notice until some significant time has passed. Any modern well designed ICE works fine for 100K miles now with the proper care.. and can work pretty well even with willful ignorance.. I know several Tesla owners that do not charge their battery "per spec" and the oldest is a 2015 model S which still thinks it has 95% of its range.. after being run to 0 a few times.. left there for months on end.. charged to 100%.. left there for months ( snow birds between east and west coast).. would I recommend that treatment ? not a chance but I do think our battery packs are significantly more durable than we give them credit for. In the bad old days, we used to have these discussions about Venturi diameters, jet sizing, lobe ramps, timing overlap etc.. I think what is happening now is we have ways to get instrumented data that we couldn't even dream of just 10 years ago from a consumer car onto our phones. And we LOVE it.. we LOVE the data.. we fondle it.. fold it.. multilate it and generally abuse it which is our collective right . And I have to say, I've learned a fair bit just through osmosis and being curious about some of the "facts" that are being presented. Good stuff

 

[FalconFour]

Think of this: DC charging isn't dictated by the station, it's controlled by the car. The car ALREADY limits the max charging current if it thinks the battery isn't warm enough.

If it needed to warm up the battery to "safely" charge, it would be limiting the charging current already. It does not. The car is asking for hundreds of amps; the station is only able to deliver tens; car acts like "gotta get that limit up" anyway.

Pretty evident there's flawed logic here. BTW, I don't think Gauss Guzzler will ever be able to click around to this logic. One of my few happy ignores on this board. Dunno what planet the guy lives on, but no common sense is permeating that head. It'd likely do everyone's sanity a favor to try out that ignore feature.

 

[Gauss Guzzler]

You are entirely missing the point several times. This thread is about how there is sensible logic when it is using an AC source, and it handles that very intelligently and sensibly and efficiently, heating only as much as is needed to deal with the real temperature conditions.

But this thread is about how it throws its brain out the window when connected to a DC source and just uses:
If source == DC, HEATTHEEVERLOVINGHELLOUTOFTHEBATTERYFOREVER

Bjorn's car used a modest 4kWh to heat an extremely cold battery for *DC* charging, not "HEATTHEEVERLOVINGHELLOUTOFTHEBATTERYFOREVER".
His other video showed similar behavior with AC charging. This energy usage appears to be nonlinearly proportional to the available charge current, whether AC or DC.

Battery degradation vs. charge temperature is a continuum so Tesla's algorithm attempts to compromise between charge speed, energy loss, and battery degradation for a wide range of charge states, temperatures, and currents. Here's an example from a cell phone battery to illustrate the concept:

So again, I'll ask the community here (since @FalconFour previously refused to answer). If the world's largest, most advanced, and most successful lithium battery producer has flippantly chosen an incorrect charge temperature profile, tell me what temperature they should have chosen? And show your work.

 

[drtimhill]

So again, I'll ask the community here (since @FalconFour previously refused to answer). If the world's largest, most advanced, and most successful lithium battery producer has flippantly chosen an incorrect charge temperature profile, tell me what temperature they should have chosen? And show your work.

Actually, to be fair, it's you who are saying they are wrong, so its for you to prove it.

 

[Gauss Guzzler]

No, it's the folks on this thread claiming to have vastly more knowledge about battery management than the entire team of Tesla engineers who have spent the last 18 years developing the most advanced battery to ever be mass produced.

Takes some serious cajones to armchair-engineer against a pedigreed team like that, so I think it's fair for me to ask you guys for some specifics to back up your allegations. You say the charge temp is wrong? OK, well by how many degrees? Is that an unfair question?

 

[Rocky_H]

Bjorn's car used a modest 4kWh to heat an extremely cold battery for *DC* charging, not "HEATTHEEVERLOVINGHELLOUTOFTHEBATTERYFOREVER".

This isn't even something that can be called correct or incorrect as it's just gibberish that doesn't make a lick of sense. You are talking about an amount of energy versus a behavioral setting with a target temperature set point. That comparing apples and tractors.
The amount of energy it used during a short time of Bjorn's test is a thing.
The "HEATTHEEVERLOBINGHELLOUTOFTHEBATTERYFOREVER" is also a thing about the behavior that Tesla has enabled for all DC charging. It sets a very high temperature target and continues to go there infinitely. We are on page 6 of this thread, and this is a real documented function of how the cars operate. For you to deny that this is happening is just like denying gravity.

His other video showed similar behavior with AC charging.

No it doesn't.

This energy usage appears to be nonlinearly proportional to the available charge current, whether AC or DC.

No, they do not operate the same way. You must not have read the first several pages of this thread.
When the cars are really cold, it is deceiving you, because they do have a similar behavior. Of course the cars need to warm up to charge, so they will look similar for a while. But their end goals are very different, so as time goes on and temperatures are warmer, they will start to demonstrate the vastly different behavior.

On AC charging, it will slow down the heating, when the battery is warm enough to support whatever charging power it is supposed to use. When DC charging, it really is on "heat endlessly" to very very high temperatures, regardless of what level of charging power it is using. It is so much so, that it overshoots what is a healthy temperature range, so that as soon as the charging connection is disconnected, the car flips over into aggressive active cooling mode to bring the battery temperature back down. It doesn't have to do that with AC charging because it never makes it that high. This was all covered in the first several pages of this thread (suggested reading material).

So again, I'll ask the community here (since @FalconFour previously refused to answer). If the world's largest, most advanced, and most successful lithium battery producer has flippantly chosen an incorrect charge temperature profile, tell me what temperature they should have chosen?

They should choose a temperature. That is the answer. So now we get to ask you why they didn't. If they have 45 kW to charge the battery with, "What temperature should they have chosen?" Tesla didn't. They have two shockingly different temperatures, depending on the irrelevant detail of whether that incoming 45 kW is marked as an AC source or a DC source. It has to match the voltage to the battery to charge it, so the amps are also going to be about the same. But it has this messed up variable where it's going to treat the same 45 kW in amazingly different ways because of something a programmer typed into the code.

And show your work.

I just did. Tesla didn't pick a temperature. This is like doing proofs in logic. The answer is that there should be a temperature for that power level. We have demonstrated that Tesla did not pick one, so therefore they failed.

No, it's the folks on this thread claiming to have vastly more knowledge about battery management than the entire team of Tesla engineers who have spent the last 18 years developing the most advanced battery to ever be mass produced.

Bull $#&*. Stop making hyperbolic nonsensical accusations.

Takes some serious cajones to armchair-engineer against a pedigreed team like that, so I think it's fair for me to ask you guys for some specifics to back up your allegations.

We did.

You say the charge temp is wrong?

Not exactly. We are saying that they are all over the place in this particular area. They are flip flopping back and forth between different temperatures and can't make up their minds.

You say the charge temp is wrong?

No, we are saying Tesla is incapable of picking one.

OK, well by how many degrees? Is that an unfair question?

It's an irrelevant question.

 

[Gauss Guzzler]

the behavior that Tesla has enabled for all DC charging. It sets a very high temperature target and continues to go there infinitely.

Bjorn's video very clearly shows the exact opposite of what you describe.

We are on page 6 of this thread, and this is a real documented function of how the cars operate.

Where is this documented? I only found 6 pages of conjecture.

When DC charging, it really is on "heat endlessly" to very very high temperatures, regardless of what level of charging power it is using.

Except in Bjorn's video, it initially split the DC power in a reasonable manner, half for pack heating and half for charging. Then after 33 minutes it decided the pack was warm enough to accept the full charge current so it stopped heating. Much like it did in his AC video.

it overshoots what is a healthy temperature range, so that as soon as the charging connection is disconnected, the car flips over into aggressive active cooling mode to bring the battery temperature back down.

Battery "health" is best optimized by using a higher temperature for charging than for storage or discharge. It's just how the chemistry works best.

They should choose a temperature. That is the answer. So now we get to ask you why they didn't.

It looks like they did. Have you supplied your findings to Bjorn? Perhaps he could explain the mismatch?

They have two shockingly different temperatures, depending on the irrelevant detail of whether that incoming 45 kW is marked as an AC source or a DC source. But it has this messed up variable where it's going to treat the same 45 kW in amazingly different ways because of something a programmer typed into the code.

I haven't seen that. Bjorn's videos clearly show similar behavior that varies with charge current and temperature as expected, but with no indication that AC and DC sources are treated differently.
BTW, you say you were "shocked" by the two temperatures that your car chose. What two temperatures were they, exactly? And without getting too deep into dendrites and stuff, can you summarize what it was about those temperatures that you found so especially shocking?

there should be a temperature for that power level. We have demonstrated that Tesla did not pick one, so therefore they failed.

What "demonstration" are you referring to? I've only seen Bjorn's demonstration of seemingly reasonable battery temperature management.

 

[cleverscreenam]

Does the S/X exhibit the same battery heating behavior?

Yes it does. I documented it in my thread Is my Model S going to start on fire? ScanMyTesla

Even with my pack already at 115f/46c, navigating to a supercharger engages the battery heater. Start the supercharging session, and if you then navigate to a supercharger again, it'll resume battery heating, even though you're already plugged in.
While supercharging, my pack goes up to 140f/60c with 0kw Thermal Controller usage, dead silent car. I then stop charging out of fear of a fire, unplug and start car in Park, FINALLY the A/C and fans roar to life at full speed until the pack cools down to 100f/38c. This is with a replacement 90 pack in a classic S 85. Today I saw 257f/125c motor temperature and 221f/105c refrigerant temperature.

 

[SigNC]

This doesn't seem abnormal. it heats to 140f and then tries to hold it there while charging.

 

[Phlier]

This doesn't seem abnormal. it heats to 140f and then tries to hold it there while charging.

Darn it, I can't find my source for the following information, so please take it with the proverbial grain of sodium...

I remember reading somewhere that the target pack temperature for the Model S (so may or may not be applicable for the 3) while AC charging is 122F. Coincidentally (maybe?), Track Mode also aims for that same pack temperature.

I'll keep looking for the source of this. Until then, please treat it for what it's worth at this point... nothing.

 

[cleverscreenam]

The stated purpose of heating the battery is to increase charge rate, not to prevent health impacts to the battery.

I managed to stop the battery heating!!!
On my Model S, after supercharging started, battery pumps 100%, 3.15kw Thermal usage with no A/C or heater in cabin, and radiator fans not spinning. Note: I use my phone navigation, not the Tesla screen, to avoid battery preheating.

I then scroll-wheel rebooted the MCU and charging continued unchanged at 72kw (on instrument cluster) while Thermal usage dropped to 0.02kw! Batt pumps 33%, Radiator fans still stationary. After the MCU booted back up, it never restarted battery heating! Seems it only checks during supercharger starting, not continously.

Try rebooting in the model 3's and reclaim your battery lifespan!

 

[Candleflame]

I managed to stop the battery heating!!!
On my Model S, after supercharging started, battery pumps 100%, 3.15kw Thermal usage with no A/C or heater in cabin, and radiator fans not spinning. Note: I use my phone navigation, not the Tesla screen, to avoid battery preheating.

I then scroll-wheel rebooted the MCU and charging continued unchanged at 72kw (on instrument cluster) while Thermal usage dropped to 0.02kw! Batt pumps 33%, Radiator fans still stationary. After the MCU booted back up, it never restarted battery heating! Seems it only checks during supercharger starting, not continously.

Try rebooting in the model 3's and reclaim your battery lifespan!

wow this is a gamechanger for the 43kw chargers in australia!

 

[kylinblue]

I don’t have a reader but I can see it when my AWD MY charging at 38kw on CCS on the dash screen while in my phone app (and on the dispenser) it says 44kw. AC isn’t running. So where did that 6kw go? Must be the heater. The ambient temp is 81F so there’s like no good reason to cook my battery. I tried your reboot tip, couldn’t stop the cooking.

I managed to stop the battery heating!!!
On my Model S, after supercharging started, battery pumps 100%, 3.15kw Thermal usage with no A/C or heater in cabin, and radiator fans not spinning. Note: I use my phone navigation, not the Tesla screen, to avoid battery preheating.

I then scroll-wheel rebooted the MCU and charging continued unchanged at 72kw (on instrument cluster) while Thermal usage dropped to 0.02kw! Batt pumps 33%, Radiator fans still stationary. After the MCU booted back up, it never restarted battery heating! Seems it only checks during supercharger starting, not continously.

Try rebooting in the model 3's and reclaim your battery lifespan!

 

[Candleflame]

someone posted here that apparently you can do a softreset while charging and when the car has rebooted it continues charging but wont enable the heater!