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

I cold soaked her last night, unplugged. Plugged her in this morning and this is what is being reported by Statsapp.
View attachment 486052
eventually it should ramp the charge rate
We're specifically talking about DC charging here. It's well known and expected that it'll warm up a cold battery. It's not so well established that it'll bake a warm battery, though, as we're discovering.
 
I have never seen specific battery heating while charging at the same rate, even down to 30F... And I am watching the OBDII data.

Allow me to walk back my comment as I am known to be wrong on occasion. I did not have OBDII data until recently so I don't have data for cold temps yet. I did just see heating with a pack temp of 7C and the heating stayed on for a bit, but I need to get more data before trying to determine how the system fully behaves.
 
This is obviously not true. The battery is heated to prevent health impacts, so that the charge rate can be increased.

You could put in 250kW to a model 3 battery at any time but it would be ruined, and even more so when it's cold.

Re-contextualise what I said though. The heating isn't necessary because it's already allowed to charge fast enough without additional heating. It of course won't let you "put in 250kW" at any time for various reasons, but specifically in regards to temperature it's already limiting you from doing so if it would be detrimental. Right?

If I actually was able to get a faster charging rate with a hotter pack, sure, I might appreciate the intentional heating if speed of charging is my goal.

Just found this thread and noticed weird heating behavior yesterday too. Was charging up to 80% and the car kept heating the battery (generating heat with stator and i saw increasing stator and battery inlet temps) ALL THE WAY to 80%, even when the car "knew" it would be finished charging in a few minutes.

Now you might say "well it needed to be warm for the charginging" but that's actually not true. Scan My Tesla shows the max allowable charge rate for any given moment (based on temps and SoC) and i could see that the battery was able to charge at a much higher rate than i was getting (was paired with another car) so clearly at the kW rate i was using, i didn't need the batteries quite as hot as Tesla wanted.

I have no concern about wasting energy, but i then drove around for the next 20-30 minutes with my pack temp around 110F which seems a bit high. Also for track days this means that you really want to finish supercharging and start track mode ASAP to get that pack temp down before hitting the track.

Also - be nice to each other lol

Though I've been very vocal about not liking their current heating scheme (mostly in regards to slower charge speeds), this might be a more defensible case. It might be readying itself for when you become the only vehicle on that Supercharger pair so that it can accept more power, which I think is a noble if unrealistic pursuit depending on the situation.

However, I'm skeptical that helps much since above 70% you're starting to get very limited in charge rate (less than 70kW if I recall correctly) and like you said, it's showing you can theoretically take more power.

I found that funny, there is never "too fast" if you're on a long trip and wanna get going...

Like another pointed out (thanks @FalconFour), you missed the very important following three words: "for that case". Where that case was grabbing dinner.

Even on a long trip I find myself in this situation especially around dinner time. A longer break is sometimes appreciated, certainly longer than a Supercharger would give considering I need to park, walk somewhere, and eventually walk back before charging is done. We can hardly grab a nearby coffee at some Superchargers and make it back in time because the walking alone takes time. This is especially useful if you want to get more charge at the top end where charging is slower.

However if there are no services and I'm truly just stopping to charge (rare, honestly) then yes, charge me up as fast as possible!


So this is AC charging and outside of most of the point of this thread, but I find it hard to believe it ramped up significantly within just 10 minutes? Implying it heated the pack in less than 10 minutes? That said I'm sure the target temp for AC charging is much different and there could even be other factors to what the Stats app was displaying.
 
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diamond.g

Active Member
Nov 5, 2015
2,520
1,469
Moyock, NC
Re-contextualise what I said though. The heating isn't necessary because it's already allowed to charge fast enough without additional heating. It of course won't let you "put in 250kW" at any time for various reasons, but specifically in regards to temperature it's already limiting you from doing so if it would be detrimental. Right?

If I actually was able to get a faster charging rate with a hotter pack, sure, I might appreciate the intentional heating if speed of charging is my goal.



Though I've been very vocal about not liking their current heating scheme (mostly in regards to slower charge speeds), this might be a more defensible case. It might be readying itself for when you become the only vehicle on that Supercharger pair so that it can accept more power, which I think is a noble if unrealistic pursuit depending on the situation.

However, I'm skeptical that helps much since above 70% you're starting to get very limited in charge rate (less than 70kW if I recall correctly) and like you said, it's showing you can theoretically take more power.



Like another pointed out (thanks @FalconFour), you missed the very important following three words: "for that case". Where that case was grabbing dinner.

Even on a long trip I find myself in this situation especially around dinner time. A longer break is sometimes appreciated, certainly longer than a Supercharger would give considering I need to park, walk somewhere, and eventually walk back before charging is done. We can hardly grab a nearby coffee at some Superchargers and make it back in time because the walking alone takes time. This is especially useful if you want to get more charge at the top end where charging is slower.

However if there are no services and I'm truly just stopping to charge (rare, honestly) then yes, charge me up as fast as possible!



So this is AC charging and outside of most of the point of this thread, but I find it hard to believe it ramped up significantly within just 10 minutes? Implying it heated the pack in less than 10 minutes? That said I'm sure the target temp for AC charging is much different and there could even be other factors to what the Stats app was displaying.
Yeah not sure what possessed me to post AC charging stuff. IIRC Stats isn’t inferring any charging data, it is coming from the API.

Does the S/X exhibit the same battery heating behavior?
 
This is obviously not true. The battery is heated to prevent health impacts, so that the charge rate can be increased.

You could put in 250kW to a model 3 battery at any time but it would be ruined, and even more so when it's cold.

You seem to be arguing with yourself. The purpose is to charge faster. Of course it will be done in a way to not damage the battery. That's a given. But the purpose remains to charge the battery faster. The BMS won't let you charge fast enough to damage the battery, so no point in even talking about that.
 
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This is true.
We have a 15kW DC charger at a local supermarket. Charging our ioniq works great there, it sends the full 15kW to the battery.

The TM3 however, takes a full 7kW to heat the battery! Which takes approximately half an hour to an hour before it slowly throttles down. That leaves us with a 8kW "fast" charge, and a pointlessly warm battery.

Due to this, it is much faster to use the 11kW onboard charger, as then the battery isn't heated.
 
This is true.
We have a 15kW DC charger at a local supermarket. Charging our ioniq works great there, it sends the full 15kW to the battery.

The TM3 however, takes a full 7kW to heat the battery! Which takes approximately half an hour to an hour before it slowly throttles down. That leaves us with a 8kW "fast" charge, and a pointlessly warm battery.

Due to this, it is much faster to use the 11kW onboard charger, as then the battery isn't heated.
If you are paying close to fifty cents a minute, that could run you over three dollars to heat the battery; likewise, if it's not cold enough to need any cabin heat with a heat pump model or you have a model with resistive heating that warm battery will equalize with the ambient temperature in a several hours. One plus, the hot traction battery could help keep your cold garage somewhat warmer in the winter like an ICE car. In this example, it cost you around twice as much to charge your Model 3 over your Ioniq if your charge session was one hour! Ignoring the cost seems like a real waste of time and energy. When Tesla first starting preconditioning, the target arrival temp at a Supercharger was 100F+ now it seems to be 120+ (Cell temps from SMT).
 

Big Dog

Active Member
Mar 7, 2016
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Irvine, CA
I bet you didn't. I'll bet you're thinking right now, "no, that's nonsense, that can't be right, let me get in this thread and tell this idiot off". Or maybe "what makes you think that, where'd you get that data?". Perhaps "no, that's just because DC charging causes the battery to heat up"? Maybe even "Tesla knows best, you're thinking too hard about this". Finally, "what's it matter?". Well, those are all reasonable thoughts from reasonable people that once tread here.
Yes, you are correct, I did not know.

But you left out the "thinking" that the vast majority of owners: "I don't" [think about it].
 
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I do wish it was more intelligent about 3rd party DCFC. In theory it should read how fast the charger is and figure out how much it needs to heat the battery to get the fastest charge, not just blindingly heat the battery up to the limit.
It is not even more intelligent when you navigate to a Tesla DCFC. You typically arrive with a very warm battery and traction battery is max heated for most, if not all, of the charging session! I see no SMT differences between arriving at a 72KW urban charger versus a 250KW Supercharger. Efficiency and owner charging costs appear to not be a priority while getting you out of the charging slot is a high priority.
 
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SigNC

Active Member
Aug 23, 2017
1,631
1,546
NC
It is not even more intelligent when you navigate to a Tesla DCFC. You typically arrive with a very warm battery and traction battery is max heated for most, if not all, of the charging session! I see no SMT differences between arriving at a 72KW urban charger versus a 250KW Supercharger. Efficiency and owner charging costs appear to not be a priority while getting you out of the charging slot is a high priority.
True but at those faster spots, even urban ones, it's not that big a deal. But at the 40kW and under it makes a big difference. Ideally they are smarter about both though.
 
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The intelligence is definitely sorely lacking. At a 50kW CHAdeMO station, it'll pump heat in constantly, effectively penalizing you by 10%-20% on speed and cost. Even worse if you find yourself at a 22kW station! And yet, at a 250kW V3 station, it still heats... but only for about a minute, then it reaches the temp target (by the battery self-heating by charge rate), then it's like -- Oh crap! I need to COOL! -- and it switches to intensive cooling (AC compressor whirrs up... radiator fan starts roaring, etc).

So why? I have no idea. The logic for battery heating is still just as flawed now 2 years later. I still observe it whenever I charge on CHAdeMO.

FWIW, there's a switch in Service Mode to disable battery heating (amusingly, the only switch on that main page), but I don't think it sticks when you exit Service Mode. Given the trouble of accessing that mode (it's geofenced, in particular), it's not a practical solution.

1641013396234.png


I have heard there's some CAN command you can send to manually disable or enable heating on demand, so maybe Scan My Tesla or tes-LAX could add the ability to nerf the battery heating? 🤔
 

MP3Mike

Well-Known Member
Feb 1, 2016
18,793
46,758
Oregon
@FalconFour someone is reporting behavior that looks like Tesla might have changed the battery pre-heating parameters:

My car was preconditioned (and garage kept where the temp was 55F over night). Vehicle had 45 minutes to precondition (had navigation set to supercharger near me). And it doesn't explain why chademo charged faster and the kW were more closely matched. I tested the chademo between switching from a 350kW to a 150kW stall.

So it went this way.

350kW gave me 37kW
Switched to chademo which gave me ~45kW in car and the 47kW on screen
Switched 150kW and it gave me the same 37kW as reported by the car. (this was the exact same stall as the chademo as the stall had the 150kW CCS1 and the chademo)

Showing significant heating on CCS but not on CHAdeMO. Any chance you can test again to see if you see similar results? (In-between all of your CCS retrofit testing...)
 
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Any chance you can test again to see if you see similar results?
Haven't had any updates since December (FSD Beta blues 😑). It still has all the same behavior today, even with CCS (eats 4kW with single motor, trying to constantly heat the battery).

Wasteful or not, it's how the car is made.
Tesla glues a literal dildo to the front of the car, and if you remove it, your whole car warranty is void. Don't question it. It's aerodynamics. You don't meet my standard for an aerodynamicsicisit. Tesla did it for a reason. Their engineers are gods that can never do anything wrong, and their decisions shall not be questioned.
 

Dave EV

Active Member
Jun 23, 2009
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Earth
Ouch. That is some really unfortunate programming. I hesitate to call it "logic".
Yeah, haven't watched the video yet, but Tesla definitely needs some better logic in heating the pack.

If you're headed to an urban or V2 SC, you probably don't need to preheat the pack as much as if you are headed to a V3.

And the heating logic needs to take into account other factors. Cutting charging speeds in half to improve charging speeds 15% only slows things down.

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
 

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