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

[Candleflame]

The bricks are balanced by BMS bleed resistors. It’s very important in series packs, as your link above suggests. That’s the point of balancing otherwise cells will eventually (actually quite rapidly) be overdischarged. Potentially imbalance can result in overcharging as well. And actually the BMS can only tolerate relatively small differences in brick capacity, even with the mechanisms it uses to balance.

So anyway the point is that overdischarge is not a problem for the end user. It absolutely is an issue but it’s not important for the owner (with the obvious caveats of course).

The car actually doesnt even limit power that much <5%. It does make me wonder whether its still possible to undervolt cells. I usually put my car in chill mode <10% because of that.

On a different note it is possible to overvolt the pack by repeatedly supercharging the car to 100% without letting it rest and BMS take OVC readings so it gets confused what the actual SOC is and may well charge to 105% true SOC etc. Thats how those fleet Model X ruined their batteries.

 

[AAKEE]

The car actually doesnt even limit power that much <5%. It does make me wonder whether its still possible to undervolt cells. I usually put my car in chill mode <10% because of that.

I have been down to -1.8% two times, by purpose to reset the BMS from overestimating the capacity.

Under thorough supervision of cell voltage of course. The car wont let you use that much power at low SOC and the lowest reading I saw was 2.7XX Volts in cell min voltage. After parking, with AC/heat off etc I read 2.9XX Volts.
I do not remember if I floored it completely but it was power limited anyway and from what I saw it did not look like you could get any cell below 2.5v or even really close.
After those low SOC runs I’m not wurried at all.

 

[Macb00kemdanno]

My 2021 SR+ is showing 5.4% battery degradation (usable capacity 50.7 kWh, NCA) after 16,000 miles, according to Tessie. Seems a bit disappointing to me at least. I used to get the rated 263 miles per charge, now I'm down to 247 to 249-ish.

 

[AAKEE]

My 2021 SR+ is showing 5.4% battery degradation (usable capacity 50.7 kWh, NCA) after 16,000 miles, according to Tessie. Seems a bit disappointing to me at least. I used to get the rated 263 miles per charge, now I'm down to 247 to 249-ish.

It is expected to loose about 5% the first year. Actually more if you live in a hot climate. This will happen regardless of if the car is driven or not. Calendar aging takes a bite from the battery the first year.

Standard range cars often use higher SOC (because of the smaller battery). This causes more wear due to higher average SOC and bigger cycles.

I guess NC is not that hot (?) and I guess you could have 50% higher degradation if you lived in hot environment.

5% is ecpected after one year. (Dont know exact age of the car but around oneyear I guess). Calendar aging reduces with time.
Also means that you’ll hit 10% after a total of 4 years and 20% will take 16 years to hit.

 

[Macb00kemdanno]

It is expected to loose about 5% the first year. Actually more if you live in a hot climate. This will happen regardless of if the car is driven or not. Calendar aging takes a bite from the battery the first year.

Standard range cars often use higher SOC (because of the smaller battery). This causes more wear due to higher average SOC and bigger cycles.

I guess NC is not that hot (?) and I guess you could have 50% higher degradation if you lived in hot environment.

5% is ecpected after one year. (Dont know exact age of the car but around oneyear I guess). Calendar aging reduces with time.
Also means that you’ll hit 10% after a total of 4 years and 20% will take 16 years to hit.

Average summer temperatures are in the mid-90s (around 35C) here in NC. But based on what you're saying, my degradation seems within spec. I typically charge to about 85 percent at the beginning of the week and drive until I'm down to about 25 to 30 percent. Rinse and repeat. I Supercharge made once or twice a month. 95% of the time, I charge at home in my garage.

 

[AlanSubie4Life]

typically charge to about 85 percent at the beginning of the week and drive until I'm down to about 25 to 30 percent. Rinse and repeat. I Supercharge made once or twice a month. 95% of the time, I charge at home in my garage.

Just follow Tesla’s advice and charge every day, if there is no inconvenience in doing so. And pick a much lower target level, again, only if there is no inconvenience.

May marginally improve the results. Lower cycle depth is also good.

But mostly wouldn’t worry about it. It will slow down.

 

[AAKEE]

Average summer temperatures are in the mid-90s (around 35C) here in NC. But based on what you're saying, my degradation seems within spec. I typically charge to about 85 percent at the beginning of the week and drive until I'm down to about 25 to 30 percent. Rinse and repeat. I Supercharge made once or twice a month. 95% of the time, I charge at home in my garage.

As Alansubie says, charge every day instead and use as low as possible charging level if you like to minimize the degradation.
For NCA, 55% or lower when the car is not used will redice the degradation with about 50%. You can not regain what you already did loose but you can minimize the future losses.
Also, if possible you can set the charging to be finished not that long before the next days drive. It will reduce the time at higher SOC.

Down below, a chart showing how NCA degrades from time x SOC x temperature.

We can see that low SOC is good, contrary to most forum rumors about ”minimum 20%”.
We also see that 100% is not that bad as the rumor days compared to 80-90%.

-When the cars is not in use, Low SOC preserves the battery. Its good to stay low and charge just before a drive, specially if going above 55% SOC.
-Smaller cycles cause much less wear (even per miles driven). Charge often makes one use small cycles*.
-Low SOC causes less wear during cycles also, so this is another incitament to use low SOC*.

*) Can not be seen in the chart above but the research/science is conclusibe about this statements.

 

[hermes01]

Not sure if this is related to the latest software update but I have noticed a huge variation in the projected range to the point it is unreliable as an estimate. For instance, driving around town, have seen the projected range as high as 999 miles and as low as 70 miles. The rated miles is displayed on the screen is 140 miles or so. Basically using the estimate from the last 30 miles. Any thoughts on what could be causing this issue? Thanks.

 

[JetSpeed]

Took delivery 5/19, 20k total mileage. I always charge to 80%. These days that equates to 156mi range. How are others with similar age/specs doing?

(Vehicle is still an SR+, never downgraded to SR)

 

[AlanSubie4Life]

Not sure if this is related to the latest software update but I have noticed a huge variation in the projected range to the point it is unreliable as an estimate. For instance, driving around town, have seen the projected range as high as 999 miles and as low as 70 miles. The rated miles is displayed on the screen is 140 miles or so. Basically using the estimate from the last 30 miles. Any thoughts on what could be causing this issue? Thanks.

This is normal (in averaging mode). The answer is always just:

(Remaining rmi * Vehicle Charging Constant in Wh/rmi ) / Recent average efficiency in Wh/mi. And is then capped at 999mi of course.

Note the position of the rated line is 5Wh/mi higher than the rated constant (Charging constant), always.

Just make sure it is in average mode and is set to last 30 miles but this screen is essentially useless anyway. Use the Trip Planner (which does have recent changes).

 

[AlanSubie4Life]

Took delivery 5/19, 20k total mileage. I always charge to 80%. These days that equates to 156mi range. How are others with similar age/specs doing?

(Vehicle is still an SR+, never downgraded to SR)

Higher capacity losses are not uncommon for that vehicle, so your ~19% loss is not unusual though probably on the high side.

 

[Bobo818]

I have a 2022 model c. I don’t drive very far most of the week. Should I keep it charged to a certain percentage to keep the battery healthy? Drain it to 15% then charge to 90%?

 

[MCSV916]

Hello all!

I just picked up a used 2019 Model 3 Standard Range +. It has about 40k miles. I also have the 19 inch rims. I want to know for those that own a similar year and model, what range are you currently getting per charge? I’ve been charging at at about 75-80% and haven’t gotten anywhere close to 200 miles. I understand the battery degrades over time but, I’m getting about 166 and highest was 179. This seems really low to me considering it’s suppose to be 240.

Its only been a couple of days since I’ve had the car, so I’m still learning about it and trying to understand everything. I’ve read plenty about the car but wanted to get an idea on what everyone is getting. I know, we all drive different but I want to know if I’m in the right area in terms of miles per percentage charge. I will try the 100% charge when i take it out of town this weekend because I understand, we’re not suppose to charge that high. Thanks in advance!

 

[AlanSubie4Life]

I’ve been charging at at about 75-80% and haven’t gotten anywhere close to 200 miles. I understand the battery degrades over time but, I’m getting about 166 and highest was 179. This seems really low to me considering it’s suppose to be 240.

It's hard to know without an exact datapoint, but this suggests you'll be around 220 miles at 100% (179/0.8, 166/0.75).

This is actually really good for this particular vehicle. It's pretty common to see 200-210 miles on those at this point.

The rims don't matter at all for these numbers.

They're a direct reflection of how much energy the BMS thinks remains. It started at 240rmi, 52.5kWh or so, and so 220rmi would be 48kWh, so about 10% loss of capacity.

You'll have a better idea when you charge to 100%.

This BMS estimate does fluctuate a bit (it has nothing to do with driving style; it just fluctuates), but if you look at the long-term trends and ignore the fluctuations, it's pretty accurate (and there's no other way to determine how much energy your pack has - the rated miles tell you directly what the best estimate in the world is for your pack).

Just plug your car in every day and keep as low a charge limit as will work for you.

 

[MCSV916]

It's hard to know without an exact datapoint, but this suggests you'll be around 220 miles at 100% (179/0.8, 166/0.75).

This is actually really good for this particular vehicle. It's pretty common to see 200-210 miles on those at this point.

The rims don't matter at all for these numbers.

They're a direct reflection of how much energy the BMS thinks remains. It started at 240rmi, 52.5kWh or so, and so 220rmi would be 48kWh, so about 10% loss of capacity.

You'll have a better idea when you charge to 100%.

This BMS estimate does fluctuate a bit (it has nothing to do with driving style; it just fluctuates), but if you look at the long-term trends and ignore the fluctuations, it's pretty accurate (and there's no other way to determine how much energy your pack has - the rated miles tell you directly what the best estimate in the world is for your pack).

Just plug your car in every day and keep as low a charge limit as will work for you.

Thanks for the response. I’ve definitely been obsessing about the miles. This is just a leisure car so I’m not too worried about not having enough range. I just wanted to see what others with 2019 SR+ are getting at this point in 2022. I will know more about the car in the coming days when I really test it out.

 

[RichardB123]

What is the exact source of your numbers? “The car’s API” and teslamate is not definitive. What does your car show at 100%? 90%

I think you are worrying unnecessarily. There is not a history of degradation. The batteries tend to lose 5% capacity or so in first year and little thereafter. Loss is not straight line.

Both the car and Teslafi show my car at 10% loss after 27000 km. No sign of flattening out yet. Teslafi says I am at the “fleet average”.

 

[RichardB123]

Most specifically, from the Tesla New Vehicle Limited Warranty

"The measurement method used to determine Battery capacity, and the decision of whether to repair, replace, or provide reconditioned or remanufactured parts, and the condition of any such replaced, reconditioned or re-manufactured parts, are at the sole discretion of Tesla."

Yep, Tesla will make the decision, it is NOT based upon miles NOR original battery capacity.
I'm going to guess that it's based upon the number of cells that have gone bad in the pack.

My 2020 SR+ battery has degraded 10% in 27000km. Tesla just says “don’t worry”. Im worried.

 

[RichardB123]

PREACH

The degradation curves are supplied by Tesla. I have my doubts. My 2020 Model 3 SR+ is showing a linear degradation of 10% after 27000 km. Teslafi says this is average for the fleet. If so, the fleet is headed for battery replacement. Everyone says” don’t worry” but it’s beginning to look like many, many cars do not have the excellent battery capacity retention results posted by some owners online.

 

[VT_EE]

Well, i'm not worried, I just want to understand how can I, a regular customer, know when and if the battery of the car goes past the threshold the vendor set for warranty.

This is what Tesla has to say about the displayed range:
Range

"Displayed range in your Tesla is adapted based on fixed EPA test data, not your personal driving patterns. It’s natural for this to fluctuate due to the nature of battery technology and how the onboard computer calculates range."

So is there a reason this displayed range can't be used as a measure of battery health?

I have yet to see someone on TMC get a replacement battery based solely on the 70% degradation warranty. I'm convinced there would have to be something terribly wrong with the battery to hit that threshold. Usually the battery completely fails beforehand.

 

[RichardB123]

i bought my model 3 in aug 2018. After the software upgrade I only got 316 miles when charged to 100%. Last night I got only 312 miles from 5% SOC to 100%. A 4% degradation within 10 months? Have others degraded similarly?

I’m at 10% loss in 23 months and only 20,000 miles.