Model 3 Performance Battery Degradation One Month (Story)

[KenC]

The service center did a CAC reset. Essentially, they did a factory reset and then for the next two weeks, it was supposed to calibrate. Well, 6 weeks later, it tanked again.

So, your BMS is flaky? What's your charging routine?

 

[gaspi101]

So, your BMS is flaky? What's your charging routine?

Correction. I’m down to 270 at 100% as of tonight. I charge to 80% every night, unless the charge is more than 70%, in which case I’ll charge the next day. For a while I was charging to 90%, then 85%, trying to see if that made any difference. No difference. So I decided to go back to just 80%, just in case this was real degradation. Kind of crazy to be seeing so much of it.

 

[gaspi101]

What is the range constant on your car?
Usable battery capacity [kWh] / Range constant [Wh/mile] = Rated range [mile]


Here is how to check if you haven't done this yet:

set the SoC to remaining range
start driving, reset the trip meter at the exact moment when the range meter drops a digit, take a note of the number
keep driving smoothly at around 65mph, better don't use high consumers like heating or AC (low consumption makes measurement more accurate)
the longer you drive the better accuracy can be achieved
once you are near the end of your trip, pick a moment when the range meter drops a digit, make a note of this number plus miles driven and the average consumption as per trip meter.

Energy consumed = miles driven * average consumption [Wh/mile] (more accurate than the number in the middle)
Range constant = Energy consumed / (range meter (at trip start) - range meter (at trip end) )

This range constant is 236-240 Wh/mile for new or low mileage cars.

I’m sorry man, I don’t quite follow. I average around 300-310 Wh/mile, mostly autopilot miles although I don’t miss an opportunity to floor it and give myself a giggle if it presents itself. Range is at 270 at 100% charge.

yesterday I drove 40.12 miles, consuming 12.7kWh, which Teslafi says consisted of an average of 302 Wh/mile.

does that answer your question?

 

[gaspi101]

I did it on the app and selected a far out service date. They contacted me from the Virtual Service dept and requested data I emailed them TeslaFI charge logs and they are reviewing. Like I said I have no idea what will come of it some say service says it is normal, some say they reset the calibration, some say they got a new battery. In the end we can all have different issues I just think it is worth having it checked remotely just in case there is actually an issue. If they say there is not issue at least if I do have a problem down the road it is documented that I inquired early on about the loss of range. Truthfully my car only seen 279 @ 90% for the first few charges and I have never seen it again in 22k miles. So when I see guys posting they are still seeing 279 or just under at 40k miles I wonder hmm could there be something wrong with my car seems at the very least possible. Also let's remember the guy that started this thread did have a real issue and got a new battery so it is worth having the car checked. Also there was a group of batteries that were not strapped correctly that is a fact so could be a few others here and there did not get strapped correctly. Again worth looking into just in case.

Thanks man. My Service Center has seen me four times on this issue, I’m reticent tomorrow bring it back up again as they keep telling me it’s normal and make me feel like I’m being an asshole. But I’m down to 270 miles at 100% tonight and that really bothers me now.

 

[hoang51]

Thanks man. My Service Center has seen me four times on this issue, I’m reticent tomorrow bring it back up again as they keep telling me it’s normal and make me feel like I’m being an asshole. But I’m down to 270 miles at 100% tonight and that really bothers me now.

Remember that change in temperature, especially when cold season swings around will drop range. A 2 mile drop isn't worth the worries. I supercharged earlier tonight and I saw 262 miles. It used to report a few miles higher (264 & 266 miles), but it looks like due to weather temperature fluctuations (~70 F -> ~60 F). Let's see how it will behave when spring swings around with nicer weather.

 

[FactsBot]

I’m sorry man, I don’t quite follow. I average around 300-310 Wh/mile, mostly autopilot miles although I don’t miss an opportunity to floor it and give myself a giggle if it presents itself. Range is at 270 at 100% charge.

This guy's description may be more clear: Model 3 Range Constant Check
But check my figures below as well.

yesterday I drove 40.12 miles, consuming 12.7kWh, which Teslafi says consisted of an average of 302 Wh/mile.

does that answer your question?

Almost. Other than these I need to know how much was the range decrease on the battery monitor. I made a quick guide.

Notice that the longer you drive the more accurate the result is.
If you only use up 20 miles rated range, then the counter could stay at 20.4 or 19.6, that could generate +-2.5% error which is too much. This is why I said, if you can't make a long trip, reset the trip meter when the range meter drops this way you know it's let's say 260 instead or 260.4 or 259.5. And similarly end the trip at the time when the range meter drops.
If you can make a long trip like 250 miles, this won't matter much as the maximum error would be 1/250 = +-0.2%

The average consumption on the trip meter is a rounded number as well. That might give another +-0.4% error.

Keep the consumption at around 250Wh/mile during the test to have an accurate measurement. Turn off AC or heating if possible.

The usable battery capacity on a brand new Model 3 LR (RWD/AWD/P) is 74.5kWh.

In the example above I used Tesla Bjorn's numbers, his car has around 6% degradation (even though the rated range is at 484km = 300.6 miles) at 25k miles.

If your number is way off, then you either didn't follow the procedure or some metering system is wrong in the BMS.

Also your Model X has some degradation too, but the range meter doesn't show it. It's impossible not to have some. If I recall, the battery capacity in that car is around 98kWh when brand new.

 

[Swampgator]

Howdy! I'm that fellow M3P owner from Reddit, and I'm sorry to say, that "fix" didn't take. Here's what Teslafi tells me now (if anyone has any ideas, I'm open to them!...SC says nothing's wrong): Imgur

I'm down to 272 miles at 100% at 19,000 miles. Meanwhile, my wife's 2017 Model X 100D with 40k miles gets 293 miles (out of original 295). Not sure what to do anymore...

Well I do think this proves that you have not experienced any actual degradation. It appears to be a BMS calibration issue. I have the same issue (280 @100%) What I think all of us want however, is not to have our actual driving range reduced because the BMS thinks we don't have enough capacity. And that is happening, at least in my case. So even though I do believe the techs when they say my battery is performing well, I am still not able to enjoy the advertised range. That is really the issue. I'm just hoping Tesla figures it out in a future OTA.

 

[juanmedina]

My performance model stealth is at 258 miles at 90% with 13k miles

 

[gaspi101]

Remember that change in temperature, especially when cold season swings around will drop range. A 2 mile drop isn't worth the worries. I supercharged earlier tonight and I saw 262 miles. It used to report a few miles higher (264 & 266 miles), but it looks like due to weather temperature fluctuations (~70 F -> ~60 F). Let's see how it will behave when spring swings around with nicer weather.

Thanks, I appreciate the tip. But temperature has been in the mid 80s for the last 10 months.

 

[gaspi101]

This guy's description may be more clear: Model 3 Range Constant Check
But check my figures below as well.



Almost. Other than these I need to know how much was the range decrease on the battery monitor. I made a quick guide.


View attachment 471016

Notice that the longer you drive the more accurate the result is.
If you only use up 20 miles rated range, then the counter could stay at 20.4 or 19.6, that could generate +-2.5% error which is too much. This is why I said, if you can't make a long trip, reset the trip meter when the range meter drops this way you know it's let's say 260 instead or 260.4 or 259.5. And similarly end the trip at the time when the range meter drops.
If you can make a long trip like 250 miles, this won't matter much as the maximum error would be 1/250 = +-0.2%

The average consumption on the trip meter is a rounded number as well. That might give another +-0.4% error.

Keep the consumption at around 250Wh/mile during the test to have an accurate measurement. Turn off AC or heating if possible.

The usable battery capacity on a brand new Model 3 LR (RWD/AWD/P) is 74.5kWh.

In the example above I used Tesla Bjorn's numbers, his car has around 6% degradation (even though the rated range is at 484km = 300.6 miles) at 25k miles.

If your number is way off, then you either didn't follow the procedure or some metering system is wrong in the BMS.

Also your Model X has some degradation too, but the range meter doesn't show it. It's impossible not to have some. If I recall, the battery capacity in that car is around 98kWh when brand new.

what an excellent idea. Now I understand, thank you. A recent roadtrip gives these stats:


198.44 Miles Driven

251.61 Rated Miles Used

308 Wh/Mile

Battery Used
88%
61.11 kWh

Avg Speed
62 MPH

so, the constant is calculating 4.117 rated miles per kWh, or 242.87 Wh/mile.

and while that’s all well and good, all I have to do is multiply the 61.11 by 0.88 to know that my usable battery is only 69.44Kwh. So....what does this data tell you?

 

[diamond.g]

what an excellent idea. Now I understand, thank you. A recent roadtrip gives these stats:


198.44 Miles Driven

251.61 Rated Miles Used

308 Wh/Mile

Battery Used
88%
61.11 kWh

Avg Speed
62 MPH

so, the constant is calculating 4.117 rated miles per kWh, or 242.87 Wh/mile.

and while that’s all well and good, all I have to do is multiply the 61.11 by 0.88 to know that my usable battery is only 69.44Kwh. So....what does this data tell you?

69.4 kWh + the 3.3 kWh buffer = 72.7 kWh, which is 2.3 kWh lower than the 75 kWh Tesla says the battery is. So that is what 3% capacity loss?

 

[gaspi101]

69.4 kWh + the 3.3 kWh buffer = 72.7 kWh, which is 2.3 kWh lower than the 75 kWh Tesla says the battery is. So that is what 3% capacity loss?

Fantastic. But as of this morning, I have 268 miles at 100% on my P3D that I bought 10 months ago brand new. So even theorizing a 3% degradation, that does me no good when the car will shut off 15% earlier than it should. Every single charge, I’m losing range. Every single goddamn charge.

 

[NOLA_Mike]

Fantastic. But as of this morning, I have 268 miles at 100% on my P3D that I bought 10 months ago brand new. So even theorizing a 3% degradation, that does me no good when the car will shut off 15% earlier than it should. Every single charge, I’m losing range. Every single goddamn charge.

I don't think what you're experiencing is normal at all. I'd say keep pestering the service center - whether they think you're an ahole or not. Maybe try another service center. I would be just as upset as you seem to be if I were experiencing the same thing (and I've owned 4 different Teslas since 2013).

Mine is down to ~264 miles rated range at 90% (started at 279 when new) at 13 months, 18,400 miles. I'm a little disappointed in the amount of loss based on my experiences with the previous Ts but accept this in the acceptable range of initial degradation. Also, I experienced almost all of that drop before 10k miles and it's been holding fairly steady around 264/90% since.

Mike

 

[diamond.g]

Fantastic. But as of this morning, I have 268 miles at 100% on my P3D that I bought 10 months ago brand new. So even theorizing a 3% degradation, that does me no good when the car will shut off 15% earlier than it should. Every single charge, I’m losing range. Every single goddamn charge.

Does the car shutdown before it reads 0 miles remaining?

 

[TimothyHW3]

Correction. I’m down to 270 at 100% as of tonight. I charge to 80% every night, unless the charge is more than 70%, in which case I’ll charge the next day. For a while I was charging to 90%, then 85%, trying to see if that made any difference. No difference. So I decided to go back to just 80%, just in case this was real degradation. Kind of crazy to be seeing so much of it.

Why would you charge to 80% every night? Do you drive that much each day? If not, that might have tricked the battery or the BMS. So it could be real degradation due to bad charging habitt, which is not very likely or a BMS thing.

You should really keep it in the 25/30%-75/80% range. I would say just charge to 100% and start a 270 miles trip driving at or below the energy graph straight line consumption and see how far you can go and write down the kWh use since last charge. Make sure you have a Supercharger at or around the 220-240 miles mark

 

[KenC]

Have you tried going to a different SC to see if they have any better ideas? And, I would try @TimothyHW3's idea and use a lower charge limit setting. 75% is not a whole lot lower than 80%, maybe try something more extreme and see if things change up. I'd try 60% for a couple weeks and see if that causes the BMS to recalibrate itself.

From the paper that was linked: "In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms."

I'm sure someone has posted it somewhere, but what does 3.92V equate to in the Model's SOC%age?

In the table that follows, they show 3.90V as 60 to 65%, but that's generically. Anyhow, I'd try 60% for a couple weeks.

 

[TimothyHW3]

I will check tomorrow and let you know - the car is now and or around 60%. I think 3.92V is even lower than that.

 

[gaspi101]

I don't think what you're experiencing is normal at all. I'd say keep pestering the service center - whether they think you're an ahole or not. Maybe try another service center. I would be just as upset as you seem to be if I were experiencing the same thing (and I've owned 4 different Teslas since 2013).

Mine is down to ~264 miles rated range at 90% (started at 279 when new) at 13 months, 18,400 miles. I'm a little disappointed in the amount of loss based on my experiences with the previous Ts but accept this in the acceptable range of initial degradation. Also, I experienced almost all of that drop before 10k miles and it's been holding fairly steady around 264/90% since.

Mike

Thanks, Mike. That's actually a spectacular idea you just had...If my local service center keeps telling me it's normal, I'll take a little drive up north to another and see what they say...I'm fairly new to Tesla, having bought my first one during the last days of December last year, but I've dived in head-first--soon after bought a used Model X for the wife, and we're awaiting solar panels and powerwalls installs...You know, they say that the Model 3 batteries are a huge upgrade from those inside my 2017 Model X...but my 2017 Model X has 40k+ miles and has suffered less than 4 miles of degradation from the original EPA amount...and that thing has been supercharged a lot! So I'm having trouble reconciling the service center's protestations of normalcy, particularly in light of the thoughtful insights of folks on this board. Thanks, man.

 

[gaspi101]

Why would you charge to 80% every night? Do you drive that much each day? If not, that might have tricked the battery or the BMS. So it could be real degradation due to bad charging habitt, which is not very likely or a BMS thing.

You should really keep it in the 25/30%-75/80% range. I would say just charge to 100% and start a 270 miles trip driving at or below the energy graph straight line consumption and see how far you can go and write down the kWh use since last charge. Make sure you have a Supercharger at or around the 220-240 miles mark

Well, from my understanding in troubleshooting this for months, charging to less than 80% regularly can actually fool the BMS into thinking there is much less capacity than there really is. This is why Tesla's guidelines are: (1) charge nightly; (2) if not in use, leave plugged in whenever possible; and (3) charge to 90% nightly to ensure a properly balanced battery.

I was doing 90% and still suffering loss; charged to 70% and same thing. I've gone through a pretty extensive trial and error routine...this is not the result of my charging habits.

 

[gaspi101]

Have you tried going to a different SC to see if they have any better ideas? And, I would try @TimothyHW3's idea and use a lower charge limit setting. 75% is not a whole lot lower than 80%, maybe try something more extreme and see if things change up. I'd try 60% for a couple weeks and see if that causes the BMS to recalibrate itself.

From the paper that was linked: "In terms of longevity, the optimal charge voltage is 3.92V/cell. Battery experts believe that this threshold eliminates all voltage-related stresses; going lower may not gain further benefits but induce other symptoms."

I'm sure someone has posted it somewhere, but what does 3.92V equate to in the Model's SOC%age?

In the table that follows, they show 3.90V as 60 to 65%, but that's generically. Anyhow, I'd try 60% for a couple weeks.

Good tip on going to another service center, I'm going to do that if I can't get this sorted. Thanks. As to charging to 60% regularly, isn't that exactly the opposite of what you're supposed to do in order to get an accurate CAC reading?