Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[RichieB]

@mrgoogle Stop thinking in miles, start thinking in percentage SoC. Miles = range = dependent on usage and BMS calculations. Percentage is calculated from your maximum usable battery capacity by a simple devision. Charge to 100% and note the ScanMyTesla figures. The SR+ should have a 54 kWh pack. If you can't charge your SR+ close to that figure something is wrong with it.

Read https://electrek.co/2017/08/24/tesla-model-3-exclusive-battery-pack-architecture/ and Model S Battery Voltage? and Sudden Loss Of Range With 2019.16.x Software to understand the tech behind the battery.

 

[Twiglett]

The earlier post from @TwoK4drSi is almost word for word what the Support Advisor told me when I took mine in to have the battery checked. He said this is a really common question from Model 3 owners.
Now I use percentage display instead of miles, then use the energy page on the odd times that I want to see what's happening.

 

[AlanSubie4Life]

44.9kWh useable and 2.1kWh buffer remaining...

my theoretical 100% is 213miles “best case” or 340-344km

4.9kWh usable remaining 4month old car

I have a 4 month old SR+ which basically never was above ~206 of the 240miles..

These numbers don't quite all add up (though they aren't that far off). What is your actual extrapolated 100% charge, from an SoC of 90%, with the battery warm? Is it 206rmi (332km) or 340km or what? Can you provide the km at 90% charge right after you finish charging?

Can you provide the capture of the SMT data? That data also does not quite add up.

Also is it a 2020 or a 2019? It sounds like a 2019?

I can only use about 41.6kWh in a fullt charged pack

You'd expect to be able to use about ~0.955*~0.98*44.9kWh = ~42kWh or so on the trip meter, for a 100% to 0% discharge. So that seems about right given your reduced 100% capacity.

If you can't charge your SR+ close to that figure something is wrong with it.

He said it charges to 44.9kWh according to SMT. That is very low for an SR+; full range would be 52.5kWh and it can probably be as high as 54kWh as you say. The good news is he is halfway to 30% four months into ownership.

 

[mrgoogle]

@mrgoogle Stop thinking in miles, start thinking in percentage SoC. Miles = range = dependent on usage and BMS calculations. Percentage is calculated from your maximum usable battery capacity by a simple devision. Charge to 100% and note the ScanMyTesla figures. The SR+ should have a 54 kWh pack. If you can't charge your SR+ close to that figure something is wrong with it.

Read Tesla Model 3: Exclusive first look at Tesla's new battery pack architecture - Electrek and Model S Battery Voltage? and Sudden Loss Of Range With 2019.16.x Software to understand the tech behind the battery.

I can’t and I am also telling I have been to Tesla and said it seems like I can only use about 41.5kWh (before I had SMT) extrapolated “kwh used” to 100%

These numbers don't quite all add up (though they aren't that far off). What is your actual extrapolated 100% charge, from an SoC of 90%, with the battery warm? Is it 206rmi (332km) or 340km or what? Can you provide the km at 90% charge right after you finish charging?

Can you provide the capture of the SMT data? That data also does not quite add up.

Also is it a 2020 or a 2019? It sounds like a 2019?



You'd expect to be able to use about ~0.955*~0.98*44.9kWh = ~42kWh or so on the trip meter, for a 100% to 0% discharge. So that seems about right given your reduced 100% capacity.




He said it charges to 44.9kWh according to SMT. That is very low for an SR+; full range would be 52.5kWh and it can probably be as high as 54kWh as you say. The good news is he is halfway to 30% four months into ownership.

I have Display on km: best case and warm battery is hovering a little bit 336-344km

Nominal full pack: 46.6kWh energy buffer 2.1kWh.. After owning the car for a few weeks I’ve planned service, had to wait 1.5monh for service, then Tesla sec told me capacity is secret, never disclosed AND check website for battery warranty (-30%). While simultaneously asking me to pay for a battery check of which they can’t share results (even though after saying this I didn’t have to pay)

So absolute best case with battery hot is 343.5 km or 213miles at 100% but usually it’s lower (still talking about warm batteries)

Battery has little to no imbalance and expected and ideal capacity is all 46.7kWh nominal and buffer of 2.1....

SeC still tells me all is fine, no errors, energy usage tips (for EV driving...).

Meanwhile I noticed the very noticeable lower useable capacity... It’s pretty much less range then a SR non plus

 

[AlanSubie4Life]

it seems like I can only use about 41.5kWh (before I had SMT) extrapolated “kwh used” to 100%

Yeah that is all normal as explained above. Multiply nominal full pack by 95.5% and then by about 98% to arrive at this number. (Should be about 43.6kWh.). Easy to arrive at a lower value because it does not count energy when parked.

Nominal full pack: 46.6kWh energy buffer 2.1kWh

Ok. Makes sense. All your numbers work out - 213 rated miles at 100% with 4.5% buffer. I would just stick to the Nominal full pack and not worry about the usable capacity. Your nominal full pack is very low of course. Pretty sure usable value is just the temperature effect which is expected. But 213 out of 240 is pretty poor!

Nothing you can do about it. I would just not worry about it and drive the car and see what happens. You have less than 30% loss which is all that matters. Definitely you are on the very low end of the distribution and it seems likely you’ll lose additional capacity over the next year. Probably not enough to get to 30% though, is my guess.

When you drove the car off the Tesla lot with 0 miles, how many rated miles at 100% did you have?

 

[lanbo]

I can’t and I am also telling I have been to Tesla and said it seems like I can only use about 41.5kWh (before I had SMT) extrapolated “kwh used” to 100%



I have Display on km: best case and warm battery is hovering a little bit 336-344km

Nominal full pack: 46.6kWh energy buffer 2.1kWh.. After owning the car for a few weeks I’ve planned service, had to wait 1.5monh for service, then Tesla sec told me capacity is secret, never disclosed AND check website for battery warranty (-30%). While simultaneously asking me to pay for a battery check of which they can’t share results (even though after saying this I didn’t have to pay)

So absolute best case with battery hot is 343.5 km or 213miles at 100% but usually it’s lower (still talking about warm batteries)

Battery has little to no imbalance and expected and ideal capacity is all 46.7kWh nominal and buffer of 2.1....

SeC still tells me all is fine, no errors, energy usage tips (for EV driving...).

Meanwhile I noticed the very noticeable lower useable capacity... It’s pretty much less range then a SR non plus

11% loss is a shame. I'm sorry man. How many kms do you drive daily? What are your charging habits? In any case, I don't think you did anything wrong. It's the f*cking battery lottery.

 

[insaneoctane]

Get yourself a CAN bus adapter, ODB2 connector with Bluetooth, and Scan My Tesla app for Android.
Then you’ll be able to read your battery pack’s capacity as reported by the BMS.

This should tell you if you’re “within specs” or whether your pack has degraded more than 30% (highly doubtful though).
Only then can you make warranty claims as Tesla guarantees 70% remaining capacity within 8 years/100,000 miles.

You should be able to use @AlanSubie4Life's constants to calculate the pack capacity without needing the CAN bus adapter....but the CAN bus adapter is pretty cool.

 

[insaneoctane]

So I spent some time to automate a battery health graph from my API data collection so that I can pull a chart automatically to track my battery health going forward. I have 2 near identical graphs with different x-axis (date and odometer) with firmware and degradation overlays. I manually adjusted the degradation calculation to be relative to 310 until the 325 firmware came out (on 3/11 for me) and then it calculates degradation relative to 325. It shows that after 45K miles and almost 2 years, that I'm sitting a little above 4% degradation.

 

[mrgoogle]

Yeah that is all normal as explained above. Multiply nominal full pack by 95.5% and then by about 98% to arrive at this number. (Should be about 43.6kWh.). Easy to arrive at a lower value because it does not count energy when parked.



Ok. Makes sense. All your numbers work out - 213 rated miles at 100% with 4.5% buffer. I would just stick to the Nominal full pack and not worry about the usable capacity. Your nominal full pack is very low of course. Pretty sure usable value is just the temperature effect which is expected. But 213 out of 240 is pretty poor!

Nothing you can do about it. I would just not worry about it and drive the car and see what happens. You have less than 30% loss which is all that matters. Definitely you are on the very low end of the distribution and it seems likely you’ll lose additional capacity over the next year. Probably not enough to get to 30% though, is my guess.

When you drove the car off the Tesla lot with 0 miles, how many rated miles at 100% did you have?

Thanks alot, how do you know this all? I still have to read this a few times before I fully understand I guess.
(Why I can only seem to use under 42kWh extrapolated, and how do I read the nominal capacity?)

I am not so sure about original 100% full, because I didn’t pay as much attention to it. Might look back at early pictures of me being happy in the car, maybe I have some with the range numbers.

Is there a guide to understanding that useable capacity better?

11% loss is a shame. I'm sorry man. How many kms do you drive daily? What are your charging habits? In any case, I don't think you did anything wrong. It's the f*cking battery lottery.

The pack has been between 90 and 40% 99% of the time, only charged to 100% shortly before a drive (in order to try “balance” )
When I drove it of the lot (it was kind of low on charge..) and it had probably around 330km at 90% (late September is when I recieved car, planned service for low capacity already through app in October)

sometimes I drive 3x 20km a day, during weekends family visit it’s more like 135km one way and back home (after AC charge) 135km again. Rarely supercharged, still have original free referral kilometers left and at home it has always been preheated on original Tesla wall charger.

Before this I drove a Renault Zoe with 41kWh useable capacity which got me better range during some mild winter circumstances (unfortunately), also that Renault batterypack still had 98.x % SoH after I sold it 3y later.

thanks for not flaming me, hoping for it either to get worse degradation soon (?) or never degrade further.. I never really had the “plus” range so in winter my range (going speedlimit) is pretty low. My estimation is -14% useable capacity (might be software related still, even though tesla checked and inly could share “no errors”

 

[AlanSubie4Life]

Thanks alot, how do you know this all? I still have to read this a few times before I fully understand I guess.
(Why I can only seem to use under 42kWh extrapolated, and how do I read the nominal capacity?)

I am not so sure about original 100% full, because I didn’t pay as much attention to it. Might look back at early pictures of me being happy in the car, maybe I have some with the range numbers.

I don't "know" anything. I'm just kind of triangulating based on data gathered from various sources:
1) EPA documents which provide exact data on DC and AC efficiency and battery capacity.
2) peoples' reports from tools like ScanMyTesla which have confirmed and refined my understanding of how things work.
3) my own experience of how the trip meter work, how the rated miles work, etc.
4) Screen captures of the Energy screen in various vehicles which allows calculation of the charging constant.

It was really confusing for me at first, but in the end it is fantastically simple.

Pack capacity is: Rated Miles @ 100% * Charging constant for your vehicle.

Note 1: You cannot use this formula to calculate kWh remaining, except at 100%.
Note 2: This formula may underestimate pack capacity for brand-new vehicles. It is only accurate for sure once loss of capacity is visible.

Charging constant info: 2020, 2019, 2018 Model 3 Battery Capacities & Charging Constants

Note: The SR line (not the SR+) is incorrect. I had incomplete data. I will correct this soon.

Note the charging constant is important, but frankly it is confusing. The main (and only) value of it, is that it can be directly calculated for any vehicle from a picture of the Energy -> Consumption screen. And then everything else flows from it. For your vehicle it is ~219Wh/rmi. So your full pack is 213rmi*219Wh/rmi = 46.6kWh.

I prefer to refer to the discharge constant, since that's what really matters:

The discharge constant is 4.5% less than the Charging constant. That's because 4.5% of the full pack energy is below 0 (the unusable (bad things can happen) buffer)! So that full rated range displayed is only 95.5% of your full capacity. Each rated mile displayed contains a certain amount of energy, equal to this discharge constant numerical value.

The trip meter constant is subtly different than the discharge constant - it is about 2% less, because for unknown reasons, the trip meter seems to fail to account for about 2% of energy usage.

So that is where the factors of 0.955 and 0.98 come from. So if you want to see what the maximum value you could see on the trip meter was, assuming you stop at 0 rated miles and don't go into the buffer, you would take your full pack capacity and multiply by 0.955, then by 0.98:

213rmi*219Wh(BMS)/rmiEPA*0.955rmi/rmiEPA*0.98Wh(trip)/Wh(BMS) = 43.7kWh (trip)

 

[Platini]

My July 2018 3LR charges to 300-302 @ 100%. Tesla service center says there are no issues.

My July 2018 3LR also charges to around 300 now. It used to be 310 miles when it was new. Tesla service tech says this is normal and there are no issues. I never experienced any "range increase" after the updates :-(

 

[ran349]

@mrgoogle- Are you sure you have a SR+, not an SR? Is there any way to confirm what you have for sure?
Do you get 4.2 volts at 100% charge? Or at least 4.1 volts at 90% charge.

 

[G26okie]

My July 2018 3LR also charges to around 300 now. It used to be 310 miles when it was new. Tesla service tech says this is normal and there are no issues. I never experienced any "range increase" after the updates :-(

The updates only affected 2020 model years so your starting point is still 310.

 

[mrgoogle]

@mrgoogle- Are you sure you have a SR+, not an SR? Is there any way to confirm what you have for sure?
Do you get 4.2 volts at 100% charge? Or at least 4.1 volts at 90% charge.

Well, I can see “plus” when I click my tesla logo, in my tesla account, and also asked SeC to check.

All the SeC could say was “how do you know all these things” Tesla never stated official pack capacity and it’s secret..

Unfortunately I have the Standard Plus model 3, but in reality it got less the. standard range capacity.

Tried 100% and drove away immediatel, also when I got to 100% ScanMyTesla said 4.184v (there is very little imbalance in pack also)

I assume it would have settled to 4.2V if I gave it some more time. (But everywhere you read that is bad so I never let it rest at 100%, nor do I frequently charge above 90)

 

[AlanSubie4Life]

Tesla never stated official pack capacity and it’s secret..

As you know, this is just false. Tesla has provided the information on pack capacity in their EPA submissions. I guess next time you are at the service center maybe you can help them with their knowledge.

 

[mrgoogle]

As you know, this is just false. Tesla has provided the information on pack capacity in their EPA submissions. I guess next time you are at the service center maybe you can help them with their knowledge.

I will try to find those EPA docs, I kind of used that information already, but they then say “we use WLTP” not EPA (even though in kilomters the cars shows 240miles x1.609 = 386km! Which is based of the EPA range.

 

[AlanSubie4Life]

I will try to find those EPA docs, I kind of used that information already, but they then say “we use WLTP” not EPA (even though in kilomters the cars shows 240miles x1.609 = 386km! Which is based of the EPA range.

https://iaspub.epa.gov/otaqpub/publist1.jsp?page=2

 

[12jdlovins]

I have a question for you as the resident battery expert I have a 2020 P3D- Stealth (19" rims) for reference. Telsa rolled out that FSD update and i lost 10 miles due to having different rims. Teslafi also has a new fleet battery graph where you can compare your battery to others. Seemingly I am the only one who lost those 10 miles... I'm wondering if you may have any ideas.

The last charge i decided to set my rims to 18" on my car and charge to 90% which is why there is that spike at the end bringing me up past the fleets average. The highest miles rated i saw prior to this was.. 310.04 and after this latest charge im at 311.7. I'm guessing thats the "power boost" they gave during that update?

All in all I'm just curious why im like the only one who seems to have had that dip. I know it's not like i lost the miles, i never had them in the first place but it just does feel... weird.

 

[MP3Mike]

The highest miles rated i saw prior to this was.. 310.04 and after this latest charge im at 311.7. I'm guessing thats the "power boost" they gave during that update?

The "power boost" was not an "energy boost". (i.e. it increased performance not range.)

 

[12jdlovins]

The "power boost" was not an "energy boost". (i.e. it increased performance not range.)

Gotcha, wrong term them. Energy boost that they put down on the FSD preview update.


On a side ish note:

My wh/mi avg is 295. Projected is 229 and with 19's my rated is 264, and with 18's its 280.

How the hell do i accurately tell how much my battery has degraded, if at all with these numbers?

average * projected = 67555 @ 90%. so at 100% its 75.061kWh. I guess thats right about where it should be at then?