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

[XLR82XS]

I have virtually no degradation after 14,000 miles. I charge to about 308-310 miles when I set it to 100%.

Perfect. Lots of people posting about being worried about degradation after a relatively short amount of time. Just follow the owners manual instructions and enjoy the car. We have 8 year warranty so dont worry too much about it with spreadsheets, tracking, etc...
Don't charge to 100% all the time and enjoy the miles.

 

[flynnstone]

My wife's 2015 S85D has next to zero battery degregation after 46k miles. Stats shows the car has 267 to 268 miles at max charge (down from 270). I guess I'm concerned about my 3's trend line because the car was holding 310 until 8500 miles and then, after a software update, it dropped to 301ish and has been trending down below 300 rather aggressively. This morning I was at 265 miles at 90%, down 15 miles or almost 5% in less than a year. I know everyone will say it's just an estimate, but I would think the estimate would only be lower if I was achieving less than the rated range for 310 mi (which I believe is ~240-245wh/mi)

With the number of people reporting the same mileage impact after a software update, (me included), i wouldn’t be so concerned that this is a hardware problem

 

[ajdelange]

So it appears that either A) charge capacity loss is typical within the first 10k/1 year... and/or B) something has been changed recently in the software to cause the charging capacity to be reported differently.

The rated range is the 100% charge estimated by the car after each charging session divided by the rated wH/mi. Thus if a S/W update changes the displayed Wh/mi number the displayed range may change even though the battery hasn't. Of course Telsa may change the software's definition of empty and full and thus the displayed battery capacity may change even the the battery hasn't. In any case, to remove one additional layer of uncertainty I track the estimated capacity of the battery in kWh rather than the mileage. It is possible to estimate the battery usable capacity from the TeslaFi reports. Simply divide the kWh added in a charge by the charge difference in percent and multiply by 100. The uncertainty in such a capacity estimate is approximately 40 divided by the difference in percent. Thus if a charge from 51 to 76% added 25 kWh the estimated capacity is 100*25/(76 - 51) = 100 kWh ± 40/25 = 100 ± 1.6 kWh. The following picture shows the history for my X. Note that the trend line was computed taking the uncertainties of the estimates into account.

Though the data so far make it appear that battery capacity has actually increased slightly (there is a 93% chance that there is actually no increase or decrease at all) since I have had the car I expect the trend to turn downward fairly soon simply because that's what happens with most cars.

 

[ybbor]

The rated range is the 100% charge estimated by the car after each charging session divided by the rated wH/mi. Thus if a S/W update changes the displayed Wh/mi number the displayed range may change even though the battery hasn't. Of course Telsa may change the software's definition of empty and full and thus the displayed battery capacity may change even the the battery hasn't. In any case, to remove one additional layer of uncertainty I track the estimated capacity of the battery in kWh rather than the mileage. It is possible to estimate the battery usable capacity from the TeslaFi reports. Simply divide the kWh added in a charge by the charge difference in percent and multiply by 100. The uncertainty in such a capacity estimate is approximately 40 divided by the difference in percent. Thus if a charge from 51 to 76% added 25 kWh the estimated capacity is 100*25/(76 - 51) = 100 kWh ± 40/25 = 100 ± 1.6 kWh. The following picture shows the history for my X. Note that the trend line was computed taking the uncertainties of the estimates into account.

View attachment 455793

Though the data so far make it appear that battery capacity has actually increased slightly (there is a 93% chance that there is actually no increase or decrease at all) since I have had the car I expect the trend to turn downward fairly soon simply because that's what happens with most cars.

on the model 3, the miles rated on the battery bar have no relationship to the cars actual Wh/M. It's an optimal estimate. On model s, you have the option to display "Ideal" vs "Rated"... on the model 3, we only have "ideal", which should always show the Tesla Rated Ideal range based on ~240 Wh/M. So when it shows less then 310, it's actual degradation.

 

[SoManyM3s]

I was down from 325 to 305ish and now back up to 325 after a few 5% to 90% charges on a road trip. It's fluctuates up and down. Drive your car. Don't worry about the rates range. You have a warranty on the battery if it falls below 70.

 

[XLR82XS]

I was down from 325 to 305ish and now back up to 325 after a few 5% to 90% charges on a road trip. It's fluctuates up and down. Drive your car. Don't worry about the rates range.

AMEN.

 

[ajdelange]

on the model 3, the miles rated on the battery bar have no relationship to the cars actual Wh/M. It's an optimal estimate. On model s, you have the option to display "Ideal" vs "Rated".

"Rated" isn't supposed to change on the S/X either but it does. That's why I prefer kWhr as a measure of capacity.

 

[VQTRVA]

I was showing about 294 miles on my Performance Model 3 at 100% charge and contacted tech support to ask about whether this was normal (mileage was about 22,000 at that point). They recommended holding off charging until at 20% or less and charging to 100% to exercise the battery. This would take several cycles, they said. I was leaving for a trip to the Grand Canyon anyway, so this was easy to do. I was able to get the capacity back up to about 308 miles (see attached graph). This data comes from the Stats Tesla app. Since I've returned from the road trip, I only charge to the usual 80% - 85%.

Your experience - which I subscribe to also - contradicts many of the viewpoints that M.3 owners have in thinking their battery is deteriorating and NOT that the battery needs some calibration as described in this post here: Battery Degradation; Sailing & Touching a Shore

I'm at 20k miles and I experienced the same sudden drop others are seeing (was 307 forever, now suddenly 299-300). I'd assume this is due to the current software, and nothing more. I calibrated my battery and it did nothing. Video will be live at 12pm EST.

How many times?

So it appears that either A) charge capacity loss is typical within the first 10k/1 year... and/or B) something has been changed recently in the software to cause the charging capacity to be reported differently.

You left out C) your BMS needs calibration and A & B are urban legends

 

[boriszima]

So it seems I am not the only one with some range drop. I charge every day to 80% which was about 242-245 miles for me. Now, some 15K miles later it’s about 238. I am not worried at this time as others said 8 years warranty and still plenty of range. I also hope it’s software adjustments rather than battery degradation.

 

[ajdelange]

Your experience - which I subscribe to also - contradicts many of the viewpoints that M.3 owners have in thinking their battery is deteriorating and NOT that the battery needs some calibration as described in this post here: Battery Degradation; Sailing & Touching a Shore

The guy that wrote that article certainly doesn't know much about celestial navigation. There is no need to 'touch' the shore occasionally (except to reset your clocks if they aren't stable enough). The whole idea behind celestial navigation is to be able to make observations from which reasonably accurate position estimates can be calculated. Part of the art is to chose those observations such that the so called "Geometric Dilution of Precision" (GDOP) is small. Without going into detail on this I think readers will be able to see that if you are sailing from east to west that observing stars only off the bow and off the stern isn't going to give you much information about how far north or south you are off course. You will need some shots to the left and right as well as fore and aft (i.e. distributed over 360 ° - that's how "geometry" gets into the name) lto get a good estimate of latitude and longitude.

The basic concept is the same in estimating battery parameters. In No. 39 I showed how to estimate the SoC from charge data and indicated that the quality of the estimate is about 40/Percent_SoC_Change. Thus if you charge from 70 to 80% your estimated SoC error is 4 kWh. If you charge from 10 to 90% your SoC is only 0.5 kWh. 1/Percent_SoC_Change is the GDOP factor here (even though there is no geometry involved we still call it GDOP or sometimes just DOP). You want it as small as possible and thus you want to feed the estimator data on charges that span as much range as practically possible. THAT is why you want to charge from low to high SoC occasionally.

So it appears that either A) charge capacity loss is typical within the first 10k/1 year... and/or B) something has been changed recently in the software to cause the charging capacity to be reported differently.

You left out C) your BMS needs calibration and A & B are urban legends

Dead wrong. Common sense says that the battery is going to lose capacity as it ages and the literature abounds with material on this phenomenon, what to do about it, how to minimize it and rates for various battery technologies. Tesla is actually considered better than most in this regard. The following picture (sorry about the lousy scan) is taken from Linden's Handbook of Batteries (Fifth Edition).

The degradation with miles is very plain. The linear trend here is about 1% loss per year.

I won't comment on B because Tesla can do anything they want in their firmware.

As to C: you battery does not need to be calibrated as discussed above.

 

[jjrandorin]

Common sense does not have much to do with the little number on the screen on a model 3 that displays battery, and it charging to a lower number than it used to. thats controlled by the car, and based on whatever tesla wants to base it on. The actual health of the battery vs what the number displays are not necessarily the same thing, but the number on the screen being 3 miles lower than it used to be is what everyone is usually concerned with.

That number seems to be effected by what you charge to, and how often you charge vs how far you drive.

 

[5_+JqckQttqck]

Plugging in whenever you can = healthier battery as the onboard systems now run off AC power instead of your battery (in a sense).

Need to hook up the AMP meter and do some tests.

 

[0ptions]

As previously mentioned, I still get 310+ miles on a full charge. This is from last night. Note that I have over 14,000 miles. Vehicle model in signature.

 

[SO16]

The first couple years you will notice the largest decline and then it tapers off. On my MS I lost about 6% over almost 3 years.

 

[ry-ballz]

Hey it's the same thread we see 4 times a week

 

[Stanwood Steve]

Are you mostly city driving?

Nice amount of recovery.

I would say that my driving is a combination of city and freeway - about 50:50 I'd guess. I live in a pretty rural area north of Seattle, so I need to drive freeways or back roads (with a a 40 mph speed limit), to get just about anywhere.

 

[Steve Martin]

On 32.2 my 12k mile P3D- was down to 298. Then after last night’s update to 32.2.2, it went down to 295. I did a two button/brake reboot and it immediately changed from 295 to 300, in the stats app. Used to always be 309 in the beginning.

Interesting. I’ll try that because I had a 9 mile drop after upgrading to 32.2.2.

 

[killertofu]

As previously mentioned, I still get 310+ miles on a full charge. This is from last night. Note that I have over 14,000 miles. Vehicle model in signature.

Shouldn't you be getting 325 miles at full? If you are consistently not getting close to that at full charge then yes, there is degradation.

 

[ajdelange]

Hey it's the same thread we see 4 times a week

I guess we start out in our relationships with these cars plagued by range anxiety and then graduate to battery degradation anxiety.

 

[0ptions]

Shouldn't you be getting 325 miles at full? If you are consistently not getting close to that at full charge then yes, there is degradation.

Not that I am aware of. My car was never 325. I purchased it when it was the 310 model. I have never experienced the "increased range" that is rumored for existing Model 3's. At no point in charging to 80% has it fluctuated from about 250 to anywhere near 260. It's between 248 and 252 when I put the slider at 80% (which to me isn't a very accurate method of selecting literally 80%).
Edit- I focus on the 80% value because that's what I charge to daily since delivery on July 5th, 2018.
2nd Edit- Furthermore, I have no change in estimated range after upgrading to 2019.32.2.2 on Monday the 16th.