I don't know if they even did that. Last year, if my pack was at 12C, I would be out of limited regen. Short of getting a TM-spy it's difficult for me to confirm or deny this is what's happening. But from a behavior standpoint, nothing has changed. I still have half my regen limited when "warm".
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I don't know if they even did that. Last year, if my pack was at 12C, I would be out of limited regen. Short of getting a TM-spy it's difficult for me to confirm or deny this is what's happening. But from a behavior standpoint, nothing has changed. I still have half my regen limited when "warm".
And add a little indicator icon in the phone app that shows when the battery heater is active.
If you're driving to a supercharger, it's likely your battery is warm enough for full speed charging already.
The battery heater in the S/X takes about 30 minutes to get a cold-soaked pack to 12c according to another post. You're better off racing your car around for 10 or 15 minutes to get the pack up to temperature instead.
See:
Energy to run the heater, HVAC, interior, etc does not charge the battery, so I fully agree with your suggestion that the battery charge gauge only shows actual charging current. With those things operating, if the SpC was not providing power, the number would be negative (and SOC/ range would drop)
If the pack weights 500 kg and is ~1/3 aluminum. Then: specific heat of Al is 921 J/kg/k so a,10 degree rise takes 9.2kJ per kg. 150 kg then takes 1,380 kJ. A kJ is also a kWs so at 10kW, it would take 138 seconds/ 2.5 minutes to heat that portion of the pack.
Overall:
Aluminum (housing): 921
Iron (steel cell cans) is 460 J/kg/s
Water (coolant) is 4,186
Lithium is 3,559
So average is likely >1,000 J/kg/k.
5,000 kJ for 500 kg pack 10 degrees K (C) not including losses to environment.
5,000 kWs with a 10 kW heater rate is 500 sec or a bit over 8 minutes. If pack is colder, or loses heat to environment, it takes even more energy/longer. This also does not include the mass of the motor/ inverter/ heating loop.
There could also be a limit on how fast they want the temperature to change that limits the heating rate.
With the level of control they have, this should not be an issue. Basically, they can add some braking torque/ inefficency by leaving the coils/ phases on longer than optimum. Then counter that with more driving torque.
Any heating power cuts range, thus the low set point for battery temp. Many types of Lithium batteries can be permanently damaged if charged at cell temps below 0C.
The reports from the Model 3 road trip are suggesting that it isn’t charging at full rate after coming off the highway in extreme cold.
I watched the video on hard acceleration and regen to warm the pack, and while that would be fun very few owners would know or be willing to do that on the highway.
I am just suggesting Tesla look at the drivetrain and figure out a way to make some extra waste heat when approaching a SuC and the battery is colder than optimal charging. They will need to check that there is range buffer to arrive with margin.
Getting the peak rate as soon as you plug in (with the lowest state of charge) is important to reducing stop times.
I guess I didn't realize that was the case. Do you have a link to that? Because under normal freeway driving (cruising), it would take about 30 minutes or so to warm up the pack. It would be an incredibly efficient motor if it was unable to provide sufficient heat to the battery pack!
First post in this thread.
I agree with you that it is the energy efficiency that doesn’t provide enough heat in freezing temps. So I am requesting they strategically make it very inefficient.
30 minutes is a odd number to pick, and is clearly quite wrong if it's cold and windy, both in theory and practice, even for Model S.
12C is not nearly enough to get full supercharging speed. Try 40C.
Left both cars out last night and took screen shots before heading out to soccer this morning. Is this showing that there is no battery heater in the 3? Look at interior temps. Neither car was driving from 1pm Saturday. 14F for S and 3F for the 3. Cars were next to each other. I can't think of any other reason for such a difference.
mod edit: removed photos with personal info.
mod edit: removed photos with personal info.
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I don't think the interior temperatures indicate whether or not the Model 3 has a battery heater. The difference could be attributed to morning sunshine on one of the cars or an interior temperature sensor that isn't quite accurate.
One thing I find interesting is that the 3 has blue "trapped" range on its battery meter and the S does not. I'd be interested in seeing the results of preheating both vehicles for 30 minutes. Does the trapped range get restored on the Model 3? Does the Model 3 show a battery heater icon? We know that the 3 does not have a battery heater, but the app may still indicate that the system is heating the battery during preheating (by energizing the motor while standing still and scavenging the waste heat that is created). Be sure that range mode is off on both vehicles before preheating them.
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I disagree. The entire floor of the vehicle is the battery. If the S was keeping the battery temp at 12C (and the 3 is not), it would be the most logical answer to why the interior temps are different.
I would also want to know how much battery drain their was, as it looks like neither was plugged in at the time.
Thanks for sharing @outdoors , but just wanted to keep your post private.
You might want to pull down the pics, or at least blur the address on the screenshots.
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I don't think you really do, do you?
His statement wasn't that the temp difference can't be because of heating in one and not the other. He said it could be for other reasons.
Another possibility could be software triggering heating at different times or frequencies.
Or simply less temperature loss in the S due to a larger battery pack/mass.
I am not saying these are the reasons. I am just saying these are other alternatives. We need more data. Such as what was the overnight temp? Were they plugged in, and if so, how much power did they draw.
I have no doubt at all that the battery hvac system is different. And it very well may not have active heating while parked. But I won't draw that conclusion until I see more data, rather than assumptions.
Hopefully I will get mine so I can do my own tests
stopcrazypp
Well-Known Member
There's a third option. The Model 3 may have different set temperatures for heating than the Model S. We know for a fact that this changed in the Model S. Given the difference in batteries in the 3 and S, we can't assume they have the same set temperature.
If you are basing this conclusion on the S, I don't think it's necessarily applicable to the 3.
On my ~60 min commute to work it can indeed take 30 mins or more for my power/regen limits to be eliminated (i.e. the pack is fully heated). However during this time I have elevated power usage attributable to the pack heater.
If the 3 doesn't have a pack heater, it's not clear that it would behave the same.
And waste heat from the motor/inverter is likely less than most people think. The S has a published average driveline power draw of ~15KW @ 55MPH on flat roads without other loads (wind, etc). I see ~20KW at 70MPH.
The motor and inverter are both pretty darn efficient. You might have a 10% total power loss between the two. That's 1.5-2KW total waste heat. And that will have a thermal transfer efficiency of <100% in to the calls. That's not a lot of energy to heat up 900+ lbs worth of cells in a 1200 lb pack. Especially if there are sub-freezing temps while you are zipping down the highway.
The 3 is even more efficient than the S, so the waste heat (from normal driving... not counting whatever the special heating mechanism may be) alone is not likely sufficient to heat a pack completely in 30 minutes in cold conditions.
Many answers are needed before anyone in a cold climate should buy a 3. This area is under-engineered in the S and X, and seems they went with the cost cutting route with the 3. Someone with a logger should absolutely confirm power draw when heating the pack both when parked and while in drive. Simple data points like these may help people avoid a mistake.
Shock-On-T
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Could just be size.
If you had also killed an elephant and a cat in your garage last night I know which would be warmer this morning. That's why Han put Luke in the Tauntaun.
If you had also killed an elephant and a cat in your garage last night I know which would be warmer this morning. That's why Han put Luke in the Tauntaun.
The BMS doesn’t keep the battery at 12C all the time. It only brings it up to that temperature when you preheat, start charging or start driving. In the example given, the vehicles were parked overnight, so I would expect that the batteries were not being actively heated.
I don't think you really do, do you?
His statement wasn't that the temp difference can't be because of heating in one and not the other. He said it could be for other reasons.
Another possibility could be software triggering heating at different times or frequencies.
Or simply less temperature loss in the S due to a larger battery pack/mass.
I am not saying these are the reasons. I am just saying these are other alternatives. We need more data. Such as what was the overnight temp? Were they plugged in, and if so, how much power did they draw.
I have no doubt at all that the battery hvac system is different. And it very well may not have active heating while parked. But I won't draw that conclusion until I see more data, rather than assumptions.
Hopefully I will get mine so I can do my own tests
I attributed the extra heat in the S interior due to a warmer pack heating the floor (heat rises), considering the vehicles were parked side by side in the same conditions. At what level does the S battery heater kick in during extreme cold?
I appologize for posting my best guesses as fact. I agree we need more 3s on the road in these conditions with better measurements to iron it out.
If Telsa would have shipped my 3 by now, I could have done some great testing in Houston this week.
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