Rated Range MP3 - Low mileage?

[sonic88]

As long as it isn't inconvenient for you and you don't mind fiddling with it, there's really no downside, I don't think. As @KenC says, feel free to change it up, see what happens.

At the moment, neither charging earlier or delayed charges would cause me any inconvenience whatsoever. I can easily adopt either approach. If one is going to show better results in more accurate estimates (and by chance result in slight increased range back), then i'm happy to continue those habits?

I would just caution that if you actually want to see what happens, you should not update your software for the duration of your experiment. There is a fair amount of circumstantial evidence that software updates can sometimes impact BMS estimate algorithms (though sometimes it may just be a coincidence).

Unfortunately, I've not keep the software versions consistent during the tests. It simply takes me a good week or more to do a single cycle i.e. 90% down to a lower soc. So only managed perhaps a cycle or two before updates appear. Will bare this in mind thou.

Also note that if it gets colder during your experiment, and your car is not garaged in a warm location, that's also going to throw off your results (BMS estimates go down when the battery is cold, because there is actually less energy available from a cold battery).

Yes agree, its not ideal as Summer is over and into Fall....so temps are declining now.
We are located in Scotland, so not exactly associated with warm and sunny weather climates.
Still double digit temps in the region of 14-11C. The car is garaged around temps of 14C or higher.

I assume before charging, it would help if the car battery is warmed up i.e. turning on HVAC for a period (30mins?) That would help with estimates, and is better for the battery when charging whilst it up to temp?
This in comparison to charging from cold. Would there be any sense in doing this?
As i have heard that turning HVAC on for short period (20-30min) before going out on a journey is good practice especially in colder climates assuming that the car is plugged in ofcourse.

 

[sonic88]

in fact, in equatorial summer (35 degrees+) it might actually be slightly harmful to keep the battery at 90% all the time due to increased voltage and the heat itself might accelerate the degeneration process. And Tesla doesnt run the coolant pumps until the battery is above 35 degrees I think. I would find a 35C battery temperature while at 90% (or 85% true SOC) unacceptable for the car to sit at. 80 -85% is probably a better compromise.

In the past few 90% charge sessions, carried out in my garage. I have left the car plugged in and sit overnight for at least a good number of hours sleeping/idling (~13hrs). Then running it down for 10-15%.
We don't get 35C temps in Scotland ? During such charging sessions its probably been around 19-21C
and sleeping/idling around 15-18C.
So i would assume those temps are not going to cause any real issue when keeping the battery at 90% for good number of hours sitting before bring the soc down the next day or two?

edit: Also I find that such high SOC arent necessary anyway in our summers. People are spoiled because you always get EPA range due to the heat and a lack of HVAC use. 75% daily charge at 35C gets you probably the same distance as 90% at 10C.

Perhaps our lower temp climates is one of the main factors for lower range? Compared to similar owners in say sunny California which have higher temps more ideal for the battery for max range.

 

[Candleflame]

In the past few 90% charge sessions, carried out in my garage. I have left the car plugged in and sit overnight for at least a good number of hours sleeping/idling (~13hrs). Then running it down for 10-15%.
We don't get 35C temps in Scotland ? During such charging sessions its probably been around 19-21C
and sleeping/idling around 15-18C.
So i would assume those temps are not going to cause any real issue when keeping the battery at 90% for good number of hours sitting before bring the soc down the next day or two?



Perhaps our lower temp climates is one of the main factors for lower range? Compared to similar owners in say sunny California which have higher temps more ideal for the battery for max range.

If you live in scotland you can leave the car at 90% no issues. In fact, being there is actually protective for the battery. Even Elon tweeted before that if you dont live in a hot climate the batteries essentially last forever because your i.e. 5-15 degrees all year round preserves the battery.
I wouldn't run your car down, just plug in every day.


The low range is caused by EVs being more efficient in hot climate (as opposed to ICE, which are more efficient when its cold). When I leave my battery is already 25C warm - so I can extract more energy from it, whereas a cold battery isnt as reactive.

AC doesnt use anywhere near as much as heating.
Even when it's piping hot here at 45 degrees, AC is probably only using around 1.5kw or so whereas when you drive around at 8 degrees in Scotland you probably easily pull 2-3kw to heat the car, nevermind that you need to have AC on to dehumidify.
The seat heaters arent as efficient as always advertised with multiple people in the cabin - they use 160W per seat on lv 3 so that adds further power draw.

Last but not least in warm climates you can drive around with summertires all year round. Even with my old gas car when I drove from the UK to Germany I'd use like 0.5-1L/100km more fuel with winter tires.

Also bear in mind that in Europe people generally drive faster than in countries with a warm climate. I.e. its not unusual to drive 85-90mph in the UK but i.e. in Australia you have to be careful because penalties for speeding are high and the speed limits low.

 

[Candleflame]

I assume before charging, it would help if the car battery is warmed up i.e. turning on HVAC for a period (30mins?) That would help with estimates, and is better for the battery when charging whilst it up to temp?
This in comparison to charging from cold. Would there be any sense in doing this?
As i have heard that turning HVAC on for short period (20-30min) before going out on a journey is good practice especially in colder climates assuming that the car is plugged in ofcourse.

I don't know for sure but I would imagine that if its i.e. 12 degrees outside its not worth to let the HVAC run with the sole purpose of heating the battery as the heating cost offset the gains in km made.
I'd turn the heating on i.e. 5-10min before you leave so its reasonably warm inside and then just drive which will warm the battery anyway.

If you go on a roadtrip its maybe a different matter, particularly if your electricity is cheap.

 

[AlanSubie4Life]

I assume before charging, it would help if the car battery is warmed up i.e. turning on HVAC for a period (30mins?) That would help with estimates, and is better for the battery when charging whilst it up to temp?

Simply won’t be enough. The car will of course warm the battery if it needs to, but it takes an *enormous* amount of energy to get the battery warm enough to maximize the energy that can be extracted. It’s nearly impossible to get the car up to to “summer time” temp - as evidenced by pre warming approaching a supercharger, even after a long stretch of driving at 80mph.

Probably the only way to reasonably assess capacity in winter is:
1) go for a long fast drive to a 250kW Supercharger
2) make sure the car pre-heats going to the Supercharger.
3) Charge from 5-10%, make sure you hit 250kW (for you with an SR+ you need to hit about 168-170kW)
4) finish the charge to 90%.
5) Assess capacity while the battery is warm. If you don’t hit 168kW at low SoC, the data is invalid and can be safely ignored.

That’s the only way I can think of to get close to correct, and I would guess that if it is below or close to freezing you will still have inaccuracy.

 

[KenC]

...Perhaps our lower temp climates is one of the main factors for lower range? Compared to similar owners in say sunny California which have higher temps more ideal for the battery for max range.

I live in one of the most northern colder states in the US, where our Summers are warmer and our Winters colder than Edinburgh. Your temp swings are relatively moderate thanks to the Gulf Stream. My car sits outside all the time. While the cold temps affect actual range, they shouldn't affect the rated range estimate too much, except on blue snow flake days, when my rated range estimates can drop as much as 30 miles! TeslaFi and other 3rd party apps do use the temp-dependent SOC api. Why? Dunno, since the car doesn't use it.

Here's my 3rd-party rated range data(in blue) downloaded into a spreadsheet, with ambient temps(in red) added, then a moving average line put in, to show how rated range estimates move in sync with temps:

 

[AlanSubie4Life]

I live in one of the most northern colder states in the US, where our Summers are warmer and our Winters colder than Edinburgh. Your temp swings are relatively moderate thanks to the Gulf Stream. My car sits outside all the time. While the cold temps affect actual range, they shouldn't affect the rated range estimate too much, except on blue snow flake days, when my rated range estimates can drop as much as 30 miles! TeslaFi and other 3rd party apps do use the temp-dependent SOC api. Why? Dunno, since the car doesn't use it.

Here's my 3rd-party rated range data(in blue) downloaded into a spreadsheet, with ambient temps(in red) added, then a moving average line put in, to show how rated range estimates move in sync with temps:
View attachment 597202

Very nice plot. Your car is doing great on range for being 20 months old. Is the latest data still showing close to 308-310 rated miles?

 

[KenC]

Very nice plot. Your car is doing great on range for being 20 months old. Is the latest data still showing close to 308-310 rated miles?

Pretty much. Would be better if Stats gave me more datapoints. Presumably, WFH has meant fewer datapoints recorded.

 

[AlanSubie4Life]

Pretty much. Would be better if Stats gave me more datapoints. Presumably, WFH has meant fewer datapoints recorded.
View attachment 597326

Last I will say since sort of off-topic, but seems like one of the best AWD I have seen. Wonder if it is the cool Maine weather or what. How many miles on the vehicle?

I’m curious whether you will finally see the drop this winter...you might have started with 80kWh or something, which would also explain things (partly explain, anyway). Who knows.

 

[KenC]

Last I will say since sort of off-topic, but seems like one of the best AWD I have seen. Wonder if it is the cool Maine weather or what. How many miles on the vehicle?

I’m curious whether you will finally see the drop this winter...you might have started with 80kWh or something, which would also explain things (partly explain, anyway). Who knows.

12,700miles, so less than normal. Normally, I'd have driven 50% more.

 

[sonic88]

Even Elon tweeted before that if you dont live in a hot climate the batteries essentially last forever because your i.e. 5-15 degrees all year round preserves the battery.
I wouldn't run your car down, just plug in every day.

What did he mean that the battery will last forever? Do you mean less capacity lost over a similar period of time compared to the same car in a hotter climate. Would be nice if that's the case?

I'm only running it down so i can try this experiment out, of letting the car see different soc's over a discharge cycle. Hoping this might help increase my range and confirm that my lost in capacity has been due to bms rather than real lost.
If this shows positive results, would it not be better to run it down as a natural habit in order to keep the range more accurate. As my driving habits is very low mileage. Hence the discharge amounts will be very small i.e 10-15% per day. I'm assume the bms would very quickly start drifting if i was to charge every day.
Dont you think?

 

[sonic88]

Simply won’t be enough. The car will of course warm the battery if it needs to, but it takes an *enormous* amount of energy to get the battery warm enough to maximize the energy that can be extracted. It’s nearly impossible to get the car up to to “summer time” temp - as evidenced by pre warming approaching a supercharger, even after a long stretch of driving at 80mph.

Probably the only way to reasonably assess capacity in winter is:
1) go for a long fast drive to a 250kW Supercharger
2) make sure the car pre-heats going to the Supercharger.
3) Charge from 5-10%, make sure you hit 250kW (for you with an SR+ you need to hit about 168-170kW)
4) finish the charge to 90%.
5) Assess capacity while the battery is warm. If you don’t hit 168kW at low SoC, the data is invalid and can be safely ignored.

That’s the only way I can think of to get close to correct, and I would guess that if it is below or close to freezing you will still have inaccuracy.

Interesting, the majority of time when i charge my car has been overnight when the car is cold.
Or has been sitting for quite sometime in the garage.
So obviously during the charge my battery is obviously not up to temperature. However, I thought during the charging process (7kw at home), that the battery would be brought up to the relevant temperature once the charge is complete (i.e. 20 - 90% soc taking over 7hrs). Hence, the completed est rated range would be fairly accurate at the end. Would this not be a fair assessment during the winter?

I very rarely supercharge and have only done so for about 5 times. Without no more free credits i tend not SuC at all. However, for public charging stations i would occasionally utilise the free Charge Place Scotland charging units instead (i.e. 50kW stations). But for the most part, i'd utilise my home 7kw charger unit when required.

 

[sonic88]

I live in one of the most northern colder states in the US, where our Summers are warmer and our Winters colder than Edinburgh. Your temp swings are relatively moderate thanks to the Gulf Stream. My car sits outside all the time. While the cold temps affect actual range, they shouldn't affect the rated range estimate too much, except on blue snow flake days, when my rated range estimates can drop as much as 30 miles! TeslaFi and other 3rd party apps do use the temp-dependent SOC api. Why? Dunno, since the car doesn't use it.

Here's my 3rd-party rated range data(in blue) downloaded into a spreadsheet, with ambient temps(in red) added, then a moving average line put in, to show how rated range estimates move in sync with temps:
View attachment 597202

Ken your car stats look amazing
What is your car usage like, and charging habits?

 

[KenC]

Ken your car stats look amazing
What is your car usage like, and charging habits?

My usage is probably what most would not recommend; which is why I say there's no real rhyme or reason to what works. I drive between 20 to 30 miles, normally, pre-WFH, and plug-in immediately. I started in Dec 2018 charging to 90%, because Winter in Maine is cold, especially with a car kept outside. In Spring, I lowered it to 80%, as that is the level I expected to keep it at, normally. I supercharged about once a month, when making regular trips to Boston. I go as low as 7%, and have been as high as 100%, twice, by accident. The Stats app makes it too easy to accidentally tap the charge limit slider, and it goes over to 100%.

In the Summer 2019, a thread started, which I linked at the bottom, a scientific discussion about battery, etc., that's when I thought I'd try charging to 60% SOC. The idea being that the key point for cathode cracking was 3,.92V or about 63%, so I wanted to keep it under that point. Anyway, it was initially a short-term experiment, and since my usage has dropped, and there have been no negative side effects, I've kept using 60%.

So, the result has been I cycle between 60 and 50%, and plug in all the time. There has been no cell imbalance issues that I can see. I suppose I can change my SOC to 85+% for a few days to fix any issues, if necessary.

ABRP also shows minimal deg. They have some way of getting info when you supercharge that gives some indication of deg that they put in their app:

As you can see in the first red box, ABRP shows I have 75.9kWh, and zero deg. The other interesting thing you can do, is calibrate your efficiency at 65mph. My AWD 3 seems to have done particularly well at 235Wh/mile. At my normal highway speeds of 75 to 80mph, I get ~265Wh/mile.

As I noted early in the thread, I think it was this thread, I'd highly recommend reading that scientific discussion of battery deg as it has lots of good info.

Battery Degradation Scientifically Explained

 

[KenC]

View attachment 597326

Here's what the same chart looks like in Stats. The data is flattened and without the temperature overlay shows no indication that the slight variation is actually temp-related. The outlier drops around 280 miles are blue snowflake days. Seeing that is when you absolutely know the Stats data is temp-dependent:

The Stats developer recently came up with a new chart:

What's interesting is that since Efficiency generally goes up with temps, you get enough of a correlation that this serves as a bit of a proxy for Temp vs Odometer. Yes, my efficiency is high because I drive almost exclusively on backcountry roads where the speed limits are 40 or 45mph, so my average speeds are 45 to 50mph, the sweet spot for efficiency. No, I don't drive like my grandmother, I like to accelerate quickly, but otherwise, I stay within 10mph of the speed limits. I've been using Vredestein Quatrac5 for the last 11 months, at about 39psi. No aero covers, so nothing particularly fuelish. The car is just efficient.

 

[AlanSubie4Life]

However, I thought during the charging process (7kw at home), that the battery would be brought up to the relevant temperature once the charge is complete (i.e. 20 - 90% soc taking over 7hrs). Hence, the completed est rated range would be fairly accurate at the end. Would this not be a fair assessment during the winter?

No. Warming the battery is wasteful. They only warm it enough to accommodate the very slow 7-10kW charging rate without damage to the battery. And no more.

So the battery will not be up to temperature just because of charging. Is this a better place to be than a cold battery, for mileage estimates? Yes. It might be within a few miles, based on @KenC’s data. But it won’t be equivalent to a mid summer battery temp. Can you use cabin heating and stator heating to warm further? Yes, but it still has limits. And it is expensive (inefficient).

1000 pounds of battery sheathed in steel/aluminum takes a LOT of power to warm up. 3-6kW is not really enough, and in any case it will stop heating when the battery is warm enough to give you some regen. Any more would be wasteful!

That temp for the pack is going to be something like 50-60F, probably. Can watch some videos with SMT to see how warm it actually gets steady state. Probably depends on the SoC.

I don’t know the exact temperatures, but anyway you can see the tradeoff they have to make here. It is an optimization problem.

That is why I recommend the supercharger at max rate to eliminate doubt - prewarming can occur even on a summer drive. So quite a high temp is needed to get a good charge rate. A higher temp is required than for regen and way higher than for home charging.