2022.40.4.1 preconditioning changes NOT

[PagodaY]

Got 2022.40.4.1 installed on my MY 2020 last week, just before I left on a trip from NY to Denver and was really hoping the battery preconditioning was fixed (according to the release notes). My real life experience with it, in chilly weather (20-30F), shows me it hasn't improved at all.


The worst case was in Wisconsin when the temps were around 20. The preconditioning notice came on about 60 miles away from the SC. I figured that because it was cold, this was correct. After about 30 miles it went off. I assume that means the battery was up to the proper temp. 10 miles later the notice came back on. I am guessing the temp of the battery cooled down enough that it would require some more heat. 10 miles later it went off. about 5 miles from the SC it came back on.


According to the new energy graphs, of the 50% battery used, 40% was for driving and 10% was for battery conditioning! That's crazy.


So my take away is that the battery preconditioning has not been improved. Using the preconditioning uses up so much energy that any time savings gained at the SC having the battery at temp is negated by the increased amount of energy needed to "fill the tank" back to where it would have been filled had I not used the juice up preconditioning.


The automatic preconditioning should be smart enough to only heat the battery once, based on outside temp, battery temp and time/distance to the SC. Not waste energy heating the battery so soon that it requires additional heating sessions to make sure you arrive at the SC with the battery all warm and cozy.


How about this - give us the ability to manually control the preconditioning, showing us the current temp of the battery and the desired temp of the battery. We shouldn't have to trick the car into doing it properly by navigating to a location that is close to the SC and at some point guess when it would be best to switch navigation to the SC.


Anybody else experiencing this, or is it some quirk on my car?

 

[Operator64]

Just for conversation sake……….if the precondition alert had stayed on the whole 60 miles and used 15% of battery that would have been better? 10% of the 50% used (2.8-3.6 kWh ) would take approximately 3-4 minutes to replenish , depending on many different conditions.
Did driving conditions change in the 60 miles? Pulling less energy from the battery could have caused it to cool slightly, or pulling more May have caused it to warm quicker than expected, road conditions will also have an affect different road surfaces cool / warm at different rates, maybe one notification saying the car will precondition and never turn on again until after the next charge would be easier so people don’t overthink it.

 

[derotam]

Is your complaint just that you think the car should be smart enough to do what it needs to do in one shot, or that it uses a bunch of power? I agree with the former, though it is an interesting problem. Would have to create the windchill curves for the battery, coolant and motor systems and have all the models for what happens with different windspeeds from different directions...etc. As far as using too much power and whether this is all worth it...

Lets try this thought experiment, worst case(?)...

Main assumption, based on past supercharger routed preconditioning data and the fact that standstill supercharger routed preconditioning data is the same currently(I have current test data IRT 2018 LR RWD), max energy (at standstill) for each motor is about 3.5-4kW for preconditioning heat generation. At speed, based on my current tests, there is a considerable amount of that available while driving at highway speeds.

Ok so moving on...60 miles at 60mph. 8kw total energy added to front and rear motors for additional heating for the battery. That is 8kWh used. Lets say 20 minute estimated charge time at the supercharger. So to break even with the additional power used to warm up the battery, the additional battery temperature needs to allow for 24kW additional supercharger power averaged over those 20 minutes. That break even point improves the longer you charge.

Now is that in the realm of possibility? I don't really have an educated guess at this point. 3 years ago I would say absolutely no, but with the new way the supercharger routed preconditioning works, my gut says it could be possible. The data required to figure this out is full graphs of supercharger charge rate vs battery temperature all referenced to starting and ending SOC. I don't use superchargers enough nor have the willpower/time to force myself to attempt to start getting this data. Maybe someone else can.

 

[PagodaY]

Well, my reaction to this preconditioning may be a result of driving long hours and having nothing else to do but think on the long stretches of I80. I may have had unreasonable expectations of the software update benefits.

My "complaint" is that the car should be smarter. It knows the weather conditions (it warned me the day before of "Gusty winds ahead"), it knows the distance, it knows my driving speeds and the type of driving between the current location and the SC and it knows the battery status. The power consumption vs recouping the power at the SC and the time it takes seems minuscule, though I do recognize that fast charging a warm battery is probably better for the health of the pack.

The conditions of that particular drive did not change appreciably. Temps were in the 20s the whole time. Light snow squalls, gusty winds. All superhighway driving, keeping steady at 70 or less.

The road is calling. I'll try my "manual" precondition method today in Nebraska.Thanks for all the input. When I get home I'll try to digest it more

 

[derotam]

Hey I agree that it should be smarter, but it is WAY smarter than it was 4 years ago! 4 years ago, it couldn't precondition AT ALL while in motion(over ~30mph) on a RWD vehicle.

I am still up in the air(since I don't have appropriate data) as to whether any supercharger routed preconditioning actually is worth it from a time/energy use standpoint....health of the battery sure, but time/energy not so sure.

 

[Operator64]

Well if you are traveling on I80 not much entertainment however I80 does not go through Wisconsin maybe you were off course creating the issue?

 

[GtiMart]

I believe your complaint is unjustified. I've checked battery conditioning using ScanMyTesla on my latest trip. I wasn't in 2022.40 so this behavior was there before. The car starts preconditioning far away as you mention when the battery is very cold. After a while it does stop before arrival, but at that point the battery is not yet at the proper temperature (say 110F). The car just starts early to make sure it will be able to get it hot enough. After it stops generating heat actively, it continues to circulate the residual heat from the stators into the battery so it continues to warm up without spending any additional energy. As you get close to the SC, it starts heating actively again to make sure it reaches the SC at the right temp. I don't see any wasted energy.

 

[MP3Mike]

One of the main changes with the battery heating in this version is to not heat the battery while charging at a low power DC site, unless it is really necessary for the battery health. (Before it would use 7kW to heat the battery while charging at a 15kW DC site, waisting 50% of the energy, while AC charging at 15kW wouldn't heat the battery at all because it wasn't necessary)

 

[derotam]

One of the main changes with the battery heating in this version is to not heat the battery while charging at a low power DC site, unless it is really necessary for the battery health. (Before it would use 7kW to heat the battery while charging at a 15kW DC site, waisting 50% of the energy, while AC charging at 15kW wouldn't heat the battery at all because it wasn't necessary)

And yet, the car still heats the battery on AC charging. Just took that data yesterday. Now it all revolves around what temperature vs charge rate causes unacceptable damage to the battery. According to my test yesterday, battery temperature below 7C mandates battery heating which in the case of the 2018 LR RWD means 3.5kW going to the rear stator with the balance for charging. I was using 24A/240V.

 

[GtiMart]

Yes, they adjusted heating for DC, they didn't remove heating Still required to protect the battery, with different temperatures depending on the input power now.

 

[derotam]

Yes, they adjusted heating for DC, they didn't remove heating Still required to protect the battery, with different temperatures depending on the input power now.

Strictly speaking from a damage perspective, you cannot change the temperature for protecting the battery based on input power, you can only change the allowable input power based on the temperature damage threshold.

This is a hard issue because it starts getting into the difference of what people perceive as unnecessary heating vs the acceptable level of damage/degradation to the battery that Tesla wants to allow. Things have drastically changed over the years and I don't think anyone knows for sure(except Tesla) whether these changes are primarily to increase charging efficiency or decrease battery damage/degradation.

 

[DrChaos]

Strictly speaking from a damage perspective, you cannot change the temperature for protecting the battery based on input power, you can only change the allowable input power based on the temperature damage threshold.

This is a hard issue because it starts getting into the difference of what people perceive as unnecessary heating vs the acceptable level of damage/degradation to the battery that Tesla wants to allow. Things have drastically changed over the years and I don't think anyone knows for sure(except Tesla) whether these changes are primarily to increase charging efficiency or decrease battery damage/degradation.

Lowering degradation at the cost of requiring more frequent charging is probably the right choice.

 

[DrChaos]

Got 2022.40.4.1 installed on my MY 2020 last week, just before I left on a trip from NY to Denver and was really hoping the battery preconditioning was fixed (according to the release notes). My real life experience with it, in chilly weather (20-30F), shows me it hasn't improved at all.


The worst case was in Wisconsin when the temps were around 20. The preconditioning notice came on about 60 miles away from the SC. I figured that because it was cold, this was correct. After about 30 miles it went off. I assume that means the battery was up to the proper temp. 10 miles later the notice came back on. I am guessing the temp of the battery cooled down enough that it would require some more heat. 10 miles later it went off. about 5 miles from the SC it came back on.


According to the new energy graphs, of the 50% battery used, 40% was for driving and 10% was for battery conditioning! That's crazy.


So my take away is that the battery preconditioning has not been improved. Using the preconditioning uses up so much energy that any time savings gained at the SC having the battery at temp is negated by the increased amount of energy needed to "fill the tank" back to where it would have been filled had I not used the juice up preconditioning.

The fact that the battery was warmer earlier during the drive also meant that it operated more efficiently than if it were cold, so you got more miles out of the kWh available from that effect.

My theory is that there is a set point temperature needed for efficient driving and comfortable cabin heat, but that temperature is lower than what's needed for quickest supercharging. So you saw the first go into effect, and then the second.

It's not an easy choice to make for the algorithm, but generally people would be more motivated to charge as quickly as possible at the supercharger, particularly if the weather is poor. Tesla is not prioritizing minimum kWh from the supercharger.

 

[Park2670]

Ive seen the preconditioning take charge stops in the cold from 55+ minutes (back in 2018 before preconditioning), to 15 minutes with the battery warmed up. So I am just fine with it taking energy to heat up the battery on the way to the supercharger.

Interesting note that it took so much to heat yours up. Just did a long drive in my car at 20 degrees F. Only used 2% for battery preconditioning when going from 100% to 9%. Wonder if yours started much colder than mine?

 

[derotam]

The fact that the battery was warmer earlier during the drive also meant that it operated more efficiently than if it were cold, so you got more miles out of the kWh available from that effect.

Are you suggesting that efficiency is based on the temperature of the battery and that a colder battery would result in the motor drawing MORE energy out of the battery to go the same number of miles as it would if the battery was warm?

Or perhaps I am misinterpreting that statement and you could rephrase it.

 

[Operator64]

Are you suggesting that efficiency is based on the temperature of the battery and that a colder battery would result in the motor drawing MORE energy out of the battery to go the same number of miles as it would if the battery was warm?

Or perhaps I am misinterpreting that statement and you could rephrase it.

A batteries efficiency is relative to its optimal temperature, in the regular automotive industry a 12v battery is rated by CCA, cold cranking amps, (the amount of power it will release at a specified temperature). All batteries work in a similar manner extreme temps will create ineffencies

 

[DrChaos]

Are you suggesting that efficiency is based on the temperature of the battery and that a colder battery would result in the motor drawing MORE energy out of the battery to go the same number of miles as it would if the battery was warm?

Or perhaps I am misinterpreting that statement and you could rephrase it.

Yes, I think that's correct. I believe the internal resistance of a battery is worse and the efficiency of transfer between chemical potential energy (ion separation) and electrical energy (accelerating electrons) is lower with a colder battery.

The lowering of range is not entirely due to the car's efficiency going down in cold (aero, rain, cabin heat, tires).

Furthermore regeneration is limited the colder it is, in order to protect the battery from significant damage, and that lowers efficiency in non-constant speed driving.

There's another consideration. Depending on the external temperature, a heat pump equipped car would find it more efficient to use that heat to warm the battery than to rely on the battery's internal resistance, which is of course resistive heating, as there is a greater yield of heat energy out of the chemical energy with a heat pump.

 

[PagodaY]

Wow! All the responses to my original observation have been really helpful in furthering my understanding of what's going on with the preconditioning process. Bottom line is I'm withdrawing my thought that Tesla should provide an option to manually precondition the battery. The car is smart enough.

GtiMart's data from scanmytesla clarifys what's going on with the battery heating. It makes sense. The indicator that is presented to the driver is not the whole story, just the fact that the car is actively heating the fluids, not the battery. Those warm (hot?) fluids continue to circulate and continue to heat the battery after the indicator goes out. The second heating makes sense if the first heating is not bringing the battery up to the needed temp for faster charging. So, yes, my "complaint" was unjustified and I withdraw it.

DrChaos's point that the warmed battery, though not at the optimal temp for charging, does improve the efficiancy of the battery is another data point that needs to be considered.

And, my own observation of the app while charging at a charger after NOT preconditioning tells me that there is some battery warming going on during the charge (the heating icon comes on next to the battery icon), so I'm spending the energy to warm the battery anyway, so why not get it done before arriving at the charger!

Last but not least, Operator64 noted that I80 does not go through Wisconsin. He's correct, I was on a detour up to Milwalkee to visit a neice. I rejoined I80 outside of Davenport.

Thanks everyone for the responses, TMC comes through again!

 

[Operator64]

Wow! All the responses to my original observation have been really helpful in furthering my understanding of what's going on with the preconditioning process. Bottom line is I'm withdrawing my thought that Tesla should provide an option to manually precondition the battery. The car is smart enough.

GtiMart's data from scanmytesla clarifys what's going on with the battery heating. It makes sense. The indicator that is presented to the driver is not the whole story, just the fact that the car is actively heating the fluids, not the battery. Those warm (hot?) fluids continue to circulate and continue to heat the battery after the indicator goes out. The second heating makes sense if the first heating is not bringing the battery up to the needed temp for faster charging. So, yes, my "complaint" was unjustified and I withdraw it.

DrChaos's point that the warmed battery, though not at the optimal temp for charging, does improve the efficiancy of the battery is another data point that needs to be considered.

And, my own observation of the app while charging at a charger after NOT preconditioning tells me that there is some battery warming going on during the charge (the heating icon comes on next to the battery icon), so I'm spending the energy to warm the battery anyway, so why not get it done before arriving at the charger!

Last but not least, Operator64 noted that I80 does not go through Wisconsin. He's correct, I was on a detour up to Milwalkee to visit a neice. I rejoined I80 outside of Davenport.

Thanks everyone for the responses, TMC comes through again!

I’m glad you got everything figured out to your satisfaction and seem to be happier with its performance now. Have a great thanksgiving and be safe on the roads

 

[Jedisparky]

Just chiming in to say, this is still a very good a relevant thread. I'm a new Tesla LRMY owner and I've had all the same questions listed here. Thanks for all the input, we're still watching and reading.