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Recalibrating the battery

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I think the BMS estimate benefits from an occasional long trip where it can go limit to limit and actually measure what is coming and going in back to back continuous sessions.
I don't think it benefits the battery itself.

Another point that I think is getting lost is if range is being reported low due to shallow discharge in the flat part of the voltage curve, those miles are there.
Once you begin to drain it down and you get lowish and voltage isn't falling as fast as the BMS expects it will see that and I believe you will see miles leave the estimate at a slower rate than your energy use.
Maybe put another way 0% and 100% are determined by programmed voltage points, everything in between is a calculation with some influence of measured voltage.
Thank you for this clarification. I have been wondering how the car 'knows' when the battery is at 100%.
 
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I'm not sure how Tesla makes its range prediction, but at least on the energy display it just extrapolates from whr / mile. But clearly the IC display / battery gauge shows either miles or percent charge, so to give a useful guess as to the miles you will get from 100% it must take into account the effects of temperature for example.

Where I see a noticeable difference between Tesla and other Ev's is how they update the indicated total range during long regen periods, say going down a long hill. My Raven S is very reluctant to show a increasing range on the battery indicator. Imagine driving down a 3 mile long hill. You have driven 3 miles, but your battery has gained energy. That information is clearly useless to base longrange prediction on. Assuming your route will return to your starting elevation then you could just ignore any short term effects but then you don't know the actual charge at a given time. Pilots are very familiar with this idea.

I think it has been pretty well established in many tests and posts here over the years that the "IC display" (the battery state of charge indicator, what many people call the Guess-o-Meter or GOM) does indeed adjust for ambient temperature, but for nothing else. Some people confuse the SOC/GOM indication with the Energy app, which does consider other factors.

The Energy app -- as I understand it from reading hundreds of these discussions over the past 6 years -- considers the average rate of past energy use over the distance you chose (5, 15 or 30 miles), outside temperature, and (if you are using the navigation system) the expected elevation changes on your route. It may also consider traffic conditions and expected speeds on your route if you are using the navigation, but I am not sure that is definitely known. (The owner's manual does not tell us what factors the application considers.)

In any case, it makes sense that your Model S is "reluctant" to show any effect from a relatively short period of regenerative braking, especially if you have the average set for 30 miles.
 
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^^^ This

Also, Teslafi confirms by showing reduced energy (SOC in blue) when there is a temp drop, and the estimated range is based on the energy app estimated range settings, or possibly the average of the last trip.

SMT also confirms by showing a reduction or increase in range by a few miles due to temp swings, even at the same SoC, and Nominal capacity.

I have seen some correlation for greater capacity, say 1 KwH, when my cells are more or less in balance, say from my high of 40 mv to a low of 4 mv.

It is a bit scary going up a 4k foot grade, and and using 1500 wh/mi, but fun to gain 20+ miles of range on the way down.

The tesla nav system is excellent as showing what you can do, and is slightly conservative, just like it should be to give some buffer for unexpected short term conditions.

Set to energy to percent, nav to destination, and forget about the range!
 
I think the GOM isn't compensating for low ambient temperatures; I think it's observing that the battery is putting out less voltage than when it is warm, so the GOM is just reflecting what it knows about the battery. Image from battery university.

discharge-voltage-temperature.jpg


I think this is also why the car will warn you that if you don't plug in a low SOC car that's just stopped it may not turn back on; the hot battery has 5% remaining, but if you leave it overnight it'll have ... maybe something in the anti-brick reserve but nothing for you.
 
By coincidence, I ran across a new video from Kim Java, just posted yesterday. She quotes from some recent guidance Tesla has posted on its website support pages. She reports that Tesla's guidance about recalibrating the battery is as follows:

Tesla recommendation when suspecting range miscalculation:

· Charge to 90% nightly

o Leave vehicle plugged in after reaching 90%​

o Range should increase within “several weeks”​

· If unsuccessful, charge to 100%

o Leave plugged in until charging stops​

· Drive down to under 10% and repeat 100% charge 2-3 times until full recalibration occurs

The full video with additional comments from tesla is here:

And for people who wonder if the battery State of Charge indicator or "GOM" reflects your driving style, here is what Tesla says on their support page:
"Displayed range is based on regulating agency certification (EPA) and is not adapted based on driving pattern. Your driving behaviors and environmental conditions can impact your car's efficiency, and therefore its range. To see estimated range based on personalized energy consumption, open the Energy app."​
 
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Also saw same yesterday...great minds think alike, or perhaps we are both subscribed...more enjoyable to watch, shorter and more informative than Ben, Daerik, and even Bjorn of late...

Thanks for posting the Tesla guidance highlights regarding range, will be making a note of that for others.

I would mention her comments and observations concerning charging are best suited to M3, MY, and not necessarily 18650 powered or older MS cars. Clearly, it worked for her and she recovered her range on the M3.

On an older (2015) MS, I have had no problem with calibration even after months of storage under 60%. I have not charged over 90% in 18 months, since anything over 78%, both motors and cooling pumps run at 100%. Saw 266 out of 270 RM today.

One bone I have to pick with Tesla's guidance is the shade cast on 3rd party apps. No way do I think these apps cause problems, except owners can see what the ground truth on the BMS is...
 
Speaking of % age battery display, I use that exclusively and was wondering...

Does it stay accurate regardless of charging habits or does it also need to be recalibrated from time to time?


My thought is that the display type is just that, a type of display. Regardless of whether range or energy is selected, values will be impacted by changes in temperature and/or BMS calibration.
 
By coincidence, I ran across a new video from Kim Java, just posted yesterday. She quotes from some recent guidance Tesla has posted on its website support pages. She reports that Tesla's guidance about recalibrating the battery is as follows:

Tesla recommendation when suspecting range miscalculation:

· Charge to 90% nightly

o Leave vehicle plugged in after reaching 90%​

o Range should increase within “several weeks”​

· If unsuccessful, charge to 100%

o Leave plugged in until charging stops​

· Drive down to under 10% and repeat 100% charge 2-3 times until full recalibration occurs

The full video with additional comments from tesla is here:

And for people who wonder if the battery State of Charge indicator or "GOM" reflects your driving style, here is what Tesla says on their support page:
"Displayed range is based on regulating agency certification (EPA) and is not adapted based on driving pattern. Your driving behaviors and environmental conditions can impact your car's efficiency, and therefore its range. To see estimated range based on personalized energy consumption, open the Energy app."​

Does anyone know where she found this guidance on re-calibrating the battery? I've tried to google it, looked at Tesla's website, and also looked in my model 3 users manual, but can't find any relevant references. I'm sure I'm just being dumb. Thanks in advance!
 
So just to make sure I understand this topic clearly,

calibration or recalibration of the battery from time to time will help the computer get your EPA range display more accurate, but the actual real world real time range of the battery will not be affected. That range is determined by battery health, environmental factors,age, etc.

True or false?

Now, how about the displayed range in the Energy app? That is generally more accurate. But is it affected by calibration, or not?
 
So just to make sure I understand this topic clearly,

calibration or recalibration of the battery from time to time will help the computer get your EPA range display more accurate, but the actual real world real time range of the battery will not be affected. That range is determined by battery health, environmental factors,age, etc.

True or false?

Now, how about the displayed range in the Energy app? That is generally more accurate. But is it affected by calibration, or not?

The actual capacity of the battery is not affected by BMS calibration, true.

If the BMS was severely out if whack it might display 0 miles, or even shut down the car with battery remaining. Due to buffer size, this is unlikely.

The Energy app range display is just Rated or Ideal miles energy remaining divided by current usage, instant, or over 5,15, or 30 miles.

Navigate to a destination to get the most accurate estimate that takes into account temps and elevation.
 
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I feel that the mileage on my long range model three, 2018, has dropped somewhat significantly IMO from the full range. As a result I thought I would try this battery reset/calibration I’ve seen on these posts.

282 mile range on 100% charge before.
Ran down to zero as I parked in the garage and even put on all the heated seats and ran the climate control on high heat after, parking for 5 mins, for good measure. Definitely below/at the posted 0%.
charged to 100%.
Drum roll... Milage following 100% charge, 282 miles.
 
It does not happen overnight. You should do so many times in a row, and it takes weeks for the rated range to increase.
At least it is what I have read before.
Unless I see peer reviewed papers showing this is true, no way am I going to do this.

Tesla guidance has stated for longest life of the pack, keep the SoC mainly between 30-70%, and avoid high pack temps for long periods of time.

This jives with Jeffery Dahn presentations and common practice with li-ion packs.
 
How does Tesla determine the battery degradation on a warranty claim? Do they need to do this recalibration stuff or do they have special insight or tools to check the battery itself?
From what hear, they may charge you for a diagnosis, but will not share results and just tell you the pack is "Fine" and "Working as designed"

They can certainly see the pack voltages and BMS data. You can too, with an app like SMT and a reader adapter cable.
 
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