Battery degradation analysis?

[bd7349]

I hope mine starts gaining like that. I've been doing the 40-90% charge cycle for the last two charges, and have been losing 1-2 miles per cycle. It's running again tonight, and based on the charge rate and time left, it's on track to lose another 1-2 miles. I'll see what it's like in the morning. The only real downside to this charge cycle, for me, is that I can't top up with the free charging at work.

Wait, that's not the correct way to recalibrate the BMS though. Whoever told you that gave you the wrong information. The way I, and many others, have been told to recalibrate is to charge to 100%, then discharge to as close to 0% as you're comfortable getting (I get down to about 15-20 miles), then charge back up to 100%... then repeat that about two more times. This was told to me by multiple Tesla employees and I'd seen it mentioned many times on the Model S forum as well. Personally, this has always worked to get my battery back to reporting normally. It's gone as low as 296 at 100%, but after recalibrating it goes right back up to 309-310 at 100%.

So try the above method and report back if you notice any changes.

 

[J M L]

Wait, that's not the correct way to recalibrate the BMS though. Whoever told you that gave you the wrong information. The way I, and many others, have been told to recalibrate is to charge to 100%, then discharge to as close to 0% as you're comfortable getting (I get down to about 15-20 miles), then charge back up to 100%... then repeat that about two more times. This was told to me by multiple Tesla employees and I'd seen it mentioned many times on the Model S forum as well. Personally, this has always worked to get my battery back to reporting normally. It's gone as low as 296 at 100%, but after recalibrating it goes right back up to 309-310 at 100%.

So try the above method and report back if you notice any changes.

The 40-90% charge cycle was told to me in emails from Tesla service. So yeah, Tesla is all over the place on the best way to charge. The key thing service mentioned was that the BMS doesn't take readings from the battery unless the car has been idle for a time, so it is important to let it set idle for an hour or more before starting to charge, and after charging completes (according to them).

So, from various sources ranging from the Model 3 manual, to Musk's tweets, to other Musk's tweets, to what I've heard directly from Tesla, to second hand reports of what other people have heard directly from Tesla, this is the way to charge the Model 3:

• Charge it anytime you feel like
• Charge it when it gets below 40%
• Charge it when it gets below 20%
  
• Charge as high for the range you need
• Charge to 90%
• Charge to 80%
• Charge to 70%
• Sometimes charge to 100%
• Never charge to 100%
• Charging to 100% frequently doesn't matter, as long as it doesn't rest there too long
  
• 4 10% charges are the same as 1 40% charge
• It's better to charge fewer times
• Charge every night
• Don't charge every night if it doesn't need it
• Do the same thing that's been recommended for S and X for years
• The battery chemistry is different, ignore all of the S and X advice

Anymore?

 

[gilscales]

The 40-90% charge cycle was told to me in emails from Tesla service. So yeah, Tesla is all over the place on the best way to charge. The key thing service mentioned was that the BMS doesn't take readings from the battery unless the car has been idle for a time, so it is important to let it set idle for an hour or more before starting to charge, and after charging completes (according to them).

So, from various sources ranging from the Model 3 manual, to Musk's tweets, to other Musk's tweets, to what I've heard directly from Tesla, to second hand reports of what other people have heard directly from Tesla, this is the way to charge the Model 3:

• Charge it anytime you feel like
• Charge it when it gets below 40%
• Charge it when it gets below 20%
  
• Charge as high for the range you need
• Charge to 90%
• Charge to 80%
• Charge to 70%
• Sometimes charge to 100%
• Never charge to 100%
• Charging to 100% frequently doesn't matter, as long as it doesn't rest there too long
  
• 4 10% charges are the same as 1 40% charge
• It's better to charge fewer times
• Charge every night
• Don't charge every night if it doesn't need it
• Do the same thing that's been recommended for S and X for years
• The battery chemistry is different, ignore all of the S and X advice

Anymore?

You forgot the ol' keep it as close to 50% as you can one, as in if you only need 20% of your range available daily then charge at 40% and only charge to 60% daily

 

[Sparky4life]

There are two factors that influence rated range; one is actual physical battery degradation and the other is variances in the charge capacity estimation algorithm in the BMS. Here's what my rated range looks like over 18,000 miles.

Physical battery degradation is not reversible, so despite the fact that my rated range varied by as much as 5%, actual degradation is less than 0.5%.

 

[Sparky4life]

Something is wacky with the BMS.

It's really hard to accurately measure the capacity of a battery. To first order you can estimate it from voltage, but there's a lot of noise in that so the BMS also does 'coulomb counting' where it tries to count the electrons going in and out of the battery. That's also a source of error. To make up for this physical limitation, the BMS tries to compensate for the error with periodic recalibration.

 

[LastGas]

The first time I charged to 100% on my Model 3 LR RWD was at 7,700 miles. It charged to 310 miles, when it should have been 320-something. After a few 100% Supercharges, it's dropped to 306, almost 6% after 12,000 miles. Tesla tells me everything is fine. I have reservations.

 

[Orwell]

Max charge on my 2018 P3D+ with 20,000ish miles is 290 miles.

Charging to 80% is 260 miles.

I tried to do the reset/calibration by running the battery down to less than 5% then using the UMC to charge it back to 100%

 

[electrictorque]

Max charge on my 2018 P3D+ with 20,000ish miles is 290 miles.

Charging to 80% is 260 miles.

I tried to do the reset/calibration by running the battery down to less than 5% then using the UMC to charge it back to 100%

Have you reported to Tesla?

I have about 11k miles and @90% it shows 271 miles. Just slightly over 300 miles@100%

 

[bd7349]

Max charge on my 2018 P3D+ with 20,000ish miles is 290 miles.

Charging to 80% is 260 miles.

I tried to do the reset/calibration by running the battery down to less than 5% then using the UMC to charge it back to 100%

Curious, but how many times did you do the battery recalibration? It takes 2-3 times for it to fully balance the pack. Try doing it a couple more times and see if that (hopefully) makes a difference. You definitely shouldn't be seeing any degradation yet, I'm at 26k miles and mine still charges right up to 310 miles.

 

[MaryAnning3]

I think a LOT of the stress over degradation is really BMS rounding errors.

yep

 

[MaryAnning3]

I need to just set my display to % and just drive lol.

Good advice!

 

[MaryAnning3]

• Charge it anytime you feel like
• Charge it when it gets below 40%
• Charge it when it gets below 20%
  
• Charge as high for the range you need
• Charge to 90%
• Charge to 80%
• Charge to 70%
• Sometimes charge to 100%
• Never charge to 100%
• Charging to 100% frequently doesn't matter, as long as it doesn't rest there too long
  
• 4 10% charges are the same as 1 40% charge
• It's better to charge fewer times
• Charge every night
• Don't charge every night if it doesn't need it
• Do the same thing that's been recommended for S and X for years
• The battery chemistry is different, ignore all of the S and X advice

Anymore?

my advice is to try to mostly keep it between about 25% and 75% until you feel confident you know what your personal preferences are. That way you can be pretty confident that your battery will be in "perfect" condition for the time being. Don't worry about mileage estimates. Just display percent. Then as you develop your own values and sense of how you want to do things, you can venture into other practices if you want. There is a lot of personal preference in this. Some people want convenience and spontaneity. (Those are called "90%" people.) Some people want optimal battery longevity and don't mind planning and anticipating (25-75% people).

One other thing I would suggest as well, since you are in Colorado I think, avoid charging over 80% at a supercharger in cold weather.

SoC estimates of mileage and the actual health of your battery and capacity in kwh are two different things. The 2nd one is the important one.

 

[r1200gs4ok]

I have a dual motor LR and at 100% I am at 300 miles with about 10200 miles on the car I picked at the end of September 2018. I just recalibrated twice and got the range to less than 20 miles each time and then charged to 100%. One at a supercharger and another at home. I have supercharged 4 times.

It still says 300 miles and stops charging at that point.

I thought with one of the software updates the range was extended to 325 miles? Even at 310 I am at 3.2% but if 325 then it is 8% which seems high.

what and how are you recalibrating? sorry i am new and don't know all of the acronyms yet

 

[Whippy178]

Hi
I've done 3500km when car was new, at 100% it was reading 500km range
Now aftwr 3.5k at 100% its reading 490km

Should i be worried?

 

[DickBlonov]

There are two factors that influence rated range; one is actual physical battery degradation and the other is variances in the charge capacity estimation algorithm in the BMS. Here's what my rated range looks like over 18,000 miles.View attachment 426136

Physical battery degradation is not reversible, so despite the fact that my rated range varied by as much as 5%, actual degradation is less than

There are two factors that influence rated range; one is actual physical battery degradation and the other is variances in the charge capacity estimation algorithm in the BMS. Here's what my rated range looks like over 18,000 miles.View attachment 426136

Physical battery degradation is not reversible, so despite the fact that my rated range varied by as much as 5%, actual degradation is less than 0.5%.

It is unfortunate that Teslafi calls the reporting of the estimated range a battery degradation report. This is misleading.

Phil