The usual Battery Degradation Topic

[mjwojtukiewicz]

Just wanted to report on the experiment:
For 3 cycle charging i did:
1. not charge the car until it hits close to 20%
2. make sure to let the car sleep as long as i can
3. charge to 100%

Minimum charge before the calibration : 265miles @100%
current went back to 282@100%

I can report the battery estimation increase quite a bit and i am hopping for it to increase more.


View attachment 720153
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So my conclusion is that even though tesla recommends to charge it every night, it is probably not the best for certain type of driving like mine which is not lots of miles on a daily basis.

For what i have read, the BMS needs to be able to read the battery state at different level to properly do its job. If I always let it measure at only 1 or 2 data points, it will improperly estimate.

I will see if it reaches higher levels. I will not charge to 100% for the next cycle but until 70% unless i know i will drive far, and i will not charge every night unless it reaches less than 40%.

We will see what happens

Thanks all and sorry i did not answer earlier. i am not getting notifications and forgot about this while doing the experiment.

Adrien

Are you saying you did the 20% sleep 100% 3 times in a row?

 

[AAKEE]

There is only one type of real degradation and it will bring the battery capacity down.
Real degradation will not be reversible.

The indicated range doesnt always reflect the real range/remaining capacity.

Actions to increase range do only affect the indicated range. It can not restore real battery capacity.

By science we know that for current generation of lithium ion batterys in general and Panasonic NCA in particular the charge lewel/SOC when the battery is not in use cause calendar aging.
For the range allowed by the BMS we have less degradation the lower the SOC is when the car is not used. Tesla recommend to charge asap when reaching below 20%, and to a very probable level this is due to the risk of ending up with a emoty battery that does'nt charge the 12v lead acid battery as this might put us with a stranded car. Also, the 12v lead battery does not like to get discharged(the cell sulfates).
But fot the big battery low SOC is not an issue.

If the car stands for most part of the time during a year with high SOC( 60% or more) the degradation from time(calendar aging) will be higher or much higher than the degradation from cycles/driving.
High temperature is bad, specially in combination with high SOC.

Most owners could use charging habits that minimize the degradation. Some might not have the possibility due to not having an own charging station, and maybe a SR with the need for long drives.

Charging ”just in time”, so the charge is finish not many hours before going for the drive and having the battery at the low end during the night will help reducing the degradation.

Lowering the cycles from perhaps 80-90% charge and 50% low end before charging to charge to 50-60% with 20% low end give the same used range but less wear on the battery will also help.

 

[CheeseheadIL]

2018 Model 3 LR:
90% charge used to get 290 miles in 2018
90% charge used to get 284 miles in 2019
90% charge used to get 278 miles in 2020
90% charge gets 268 miles in 2021.

I have observed noticeable degradation after a software update that makes me believe that Tesla might be like Apple limiting battery performance through software for whatever reasons they have.

Telsa tech confirmed that warranty only kicks in after a drop below 70% retention efficiency from original specs.

I've got a 2018 Model 3 with about 25,000 miles on it. I'm mostly a suburban driver putting on 100 miles a week. Just returned from an 800 mile road trip. Ran the car battery down to < 80 miles of range. At 100% charge, 280 miles of range. Disappointing but after reading the threads, I'm guessing not surprising and not in range of Tesla doing anything about this.

 

[svusa]

I've got a 2018 Model 3 with about 25,000 miles on it. I'm mostly a suburban driver putting on 100 miles a week. Just returned from an 800 mile road trip. Ran the car battery down to < 80 miles of range. At 100% charge, 280 miles of range. Disappointing but after reading the threads, I'm guessing not surprising and not in range of Tesla doing anything about this.

I think about 10% range loss is the new normal. I would be concerned if drops to 20%! This also changes the financial model to own EV, your charging cost may not go up but range loss + winter could put a significant limitation on the ability to drive further.

 

[DougWantsALeaf]

So you drove 200 miles and ended with ~80 rated miles? That is very good for highway speeds.

 

[blkswn]

03/2020 M3 LR, 39K miles mostly highway and I'm currently at 274 rated miles at 100% which represents a 15% degradation based on 322 rated miles new. In the first year I always charged to 90% and have only gone to 100% a handful of times. Now I go to 85% and charge as often as possible though I do routinely drain the battery down as I commute 60 miles a day and chargers are sometimes taken up at work. Lifetime wh/mi of 248. TeslaFi ranks me at the bottom -- 7th percentile vs the fleet on battery capacity based on similar make and +/- 300 miles on the odometer.

 

[BoxcarX]

01/2019 M3 LR, 32K miles mostly suburban and I'm currently at 279 rates miles at 100%. I've always charged to 90% and like blkswn, only been to 100% on rare occasions. Will switch to 80% charge and maybe do that every few days. I find it odd that when you go to the Tesla site and look at the used (2018 and 2019) Model 3 list, all the LR ones are at 310-ish miles. That just marketing?

 

[pipestem]

Mine is at 85% indicated degredation after 3 years and 33k miles. I only charge to 80% except for rare long trips. That is nearly identical to the indicated degredation of 2015 my Nissan Leaf which I traded in on the Tesla, I believe the Leaf was more efficient at inner city driving, but the Tesla's nearly 3x bigger battery more than makes up for it (along with absolutely everything about the car). It's still a little disappointing if not totally surprising. I feel like improving real degredation and adding a lot more super fast charging stations are probably the 2 biggest factors for making EV's sell better everywhere.

 

[AAKEE]

Mine is at 85% indicated degredation after 3 years and 33k miles. I only charge to 80% except for rare long trips. That is nearly identical to the indicated degredation of 2015 my Nissan Leaf which I traded in on the Tesla, I believe the Leaf was more efficient at inner city driving, but the Tesla's nearly 3x bigger battery more than makes up for it (along with absolutely everything about the car). It's still a little disappointing if not totally surprising. I feel like improving real degredation and adding a lot more super fast charging stations are probably the 2 biggest factors for making EV's sell better everywhere.

Where do you live? Asking because the climate will affect degradation quite much.
What would you consider your average charge level( SOC?) You charge to 80% but whats the SOC before charging?
Your average driving seem to be about 30 miles a day, so I guess you use about 15% average day?

I guess you mean 85% capacity left and 15% degradation?

That is not a surprising number adter three years if the average SOC is high, and you live in a warm climate.

 

[AAKEE]

Most Tesla owners would probably say “battery degrawhat?”

There’s a fairy rapid loss of a few percent of capacity in a new battery. It happens in the first few thousand miles. After that the battery stabilizes, and the degradation over the next several hundred thousand miles is very slow and gradual.

For people with normal driving habits the degradation is so slow that most haven’t noticed it, and probably never will. The car will be scrapped for other reasons before the degradation becomes a problem.

There is two types of degradation.
The first one is calendar aging which happens even if the car is not used.
Second one is cyclic aging, which comes from cycles( = driving + charging).

The calendar aging is the dominant part fort most Tesla owners for the first (at least) five years.
Calendar aging reduces over time( square root of time).
Calendar aging invreases with higher SOC and higher tempersture.

Cyclic aging most often reduces with increasing cycles but it depends on the cycles size and current. The easiest eay for us to see cyclic aging is as a fixed number per Equivalent Full Cycle or miles driven.

A new Tesla long range/performance probably loose about 5%* of the battery capacity during the first year if charged to 80% due to calendar aging, even if the car isnt driven at all.
An average driver perhaps cause a cyclic aging of about 1% during the first year.

*) The calendar aging is temperature dependent so the actual value will depend on the climate etc.

This is a graph (from one of many research reports on the subject telling us the exact same thing):

Check for the NCA-graph.
80% SOC cause about 5% if the ambient temp is 25C during 10 months. This will be about 5.5% on a one year basis according to the ”square of root formula”.

Calendar aging values:
After one year 5.5%
After two years 7.8%
After three. 9.5%
After four. 11%
After eight years 15.5%

Of course this wont be a exvation exact to the points.

For the batteries in the car the average temperature for the battery cells will be higher than the ambient temp. Charging, driving and hesting from the sun will cause this.

 

[Bouba]

There is two types of degradation.
The first one is calendar aging which happens even if the car is not used.
Second one is cyclic aging, which comes from cycles( = driving + charging).

The calendar aging is the dominant part fort most Tesla owners for the first (at least) five years.
Calendar aging reduces over time( square root of time).
Calendar aging invreases with higher SOC and higher tempersture.

Cyclic aging most often reduces with increasing cycles but it depends on the cycles size and current. The easiest eay for us to see cyclic aging is as a fixed number per Equivalent Full Cycle or miles driven.

A new Tesla long range/performance probably loose about 5%* of the battery capacity during the first year if charged to 80% due to calendar aging, even if the car isnt driven at all.
An average driver perhaps cause a cyclic aging of about 1% during the first year.

*) The calendar aging is temperature dependent so the actual value will depend on the climate etc.

This is a graph (from one of many research reports on the subject telling us the exact same thing):

View attachment 778271

Check for the NCA-graph.
80% SOC cause about 5% if the ambient temp is 25C during 10 months. This will be about 5.5% on a one year basis according to the ”square of root formula”.

Calendar aging values:
After one year 5.5%
After two years 7.8%
After three. 9.5%
After four. 11%
After eight years 15.5%

Of course this wont be a exvation exact to the points.

For the batteries in the car the average temperature for the battery cells will be higher than the ambient temp. Charging, driving and hesting from the sun will cause this.

What I find interesting is that calendar aging and ambient temperature are the battery’s enemy but not usage...it doesn’t seem to matter if you drive like a granny or the dukes of hazard

 

[Apprunner]

What I find interesting is that calendar aging and ambient temperature are the battery’s enemy but not usage...it doesn’t seem to matter if you drive like a granny or the dukes of hazard

This. I drive like I stole the car and my avg Wh/mi with the 20 inch wheels was 345. I usually just charge to 55% and charge every night even if I barely used the car. After near 30k miles of hard driving, the battery is still only about 6-7% degraded.

 

[Candleflame]

This. I drive like I stole the car and my avg Wh/mi with the 20 inch wheels was 345. I usually just charge to 55% and charge every night even if I barely used the car. After near 30k miles of hard driving, the battery is still only about 6-7% degraded.

unless you floor it constantly i.e. race track energy consumption is still well below 1C so it just doesnt mattery.
Most cars are probably running at around 0.20-0.25C which just isnt significant. Flooring it for a few seconds is just irrelevant compared to hours of driving.

 

[pipestem]

Where do you live? Asking because the climate will affect degradation quite much.
What would you consider your average charge level( SOC?) You charge to 80% but whats the SOC before charging?
Your average driving seem to be about 30 miles a day, so I guess you use about 15% average day?

I guess you mean 85% capacity left and 15% degradation?

That is not a surprising number adter three years if the average SOC is high, and you live in a warm climate.

a very average climate - central North Carolina (currently 45F), in a garage. Do not charge every night so variable SOC mostly between 40 and 80%. As I said not really surprising but a little disappointing. The shared Tesla owner data from the model S era showed expected indicated range loss to plateau more in the 7 to 10% range. This could be due to the resetting effect in the OP post. Moreover though I have not saved all the data I feel like the indicated range has dropped unevenly in chunks so it’s difficult to know if it is plateauing.

Indicated range is not a perfect measure of either real range or real capacity, but that’s what we have to go on when deciding if that next charging stop is needed or not.

I disagree with the previous statement that cars would be junked before the battery level is insufficient. Yes the electronics and features will become outdated but the 2nd, 3rd, etc owners won’t care as much. They would care about range. I hope EV cars can have a nice lifetime. People are still buying old Leaf(?) and MS.

I don’t think more massive batteries are the answer. That is not fleet efficient and 300 mile range is pretty good. Faster charging and more chargers in more locations to give people confidence in travel would be better.

 

[ucmndd]

. Do not charge every night so variable SOC mostly between 40 and 80%.

You’re not doing yourself any favors with these charging habits.

I bet a lot of your “degradation” is due to BMS drift on account of the infrequent charging and rarely/ever exceeding 80% SOC.

Lots of threads around here on getting some of that “lost” energy back by increasing your max SOC and allowing the BMS to recalibrate over time.

 

[AAKEE]

You’re not doing yourself any favors with these charging habits.

I bet a lot of your “degradation” is due to BMS drift on account of the infrequent charging and rarely/ever exceeding 80% SOC.

Lots of threads around here on getting some of that “lost” energy back by increasing your max SOC and allowing the BMS to recalibrate over time.

That ”lost” capacity was never really lost. Just the BMS that lost the track. The energy was there.

So the choice of way to follow depends on which we think is most important, the range number or the true capacity…?

 

[Bouba]

That ”lost” capacity was never really lost. Just the BMS that lost the track. The energy was there.

So the choice of way to follow depends on which we think is most important, the range number or the true capacity…?

It’s obvious from the thousands of posters...only the true capacity will give peace of mind

 

[pipestem]

That’s why I referred to it as indicated range.

According to the OP the recipe for restoring range estimate is s little different. It would be nice if T would produce a very detailed guide on the topic. Have they?

 

[SilverSp33d3r]

Turn off cabin overheat and sentry.

Charge to 100, unplug, let sleep overnight. Discharge to as close to zero as comfortable. Let sleep overnight.

Do not check app during sleep cycles.

Doing this I went from 210 max to 230 max on SR+

 

[pacman3000]

Long-time board troll, first post ever.

Considering that this is just the BMS projection everyone is calibrating... is it really worth the risk overcharging/discharging the battery and letting it sit in that state? Musk/Tesla have mentioned that charging above 90%, without using it immediately thereafter or letting the battery sit below 20% for an extended period... are not very good for the battery.

I'd say just drive the car and let the BMS do it's job. If it loses track of the overall range because you only use 20-30 miles a day, then at least you can rest assured that the total battery range is being under-sold. If you are really worried about the projected range.... a safer approach would be to plan a long day trip and charge it to 100% to use immediately afterwards.... then use up as much battery as possible and charge it back to your daily limit (70-90%).

It is important to remember that there are thousands of cells managed by the BMS. So, as long as you keep the State-of-Charge in that happy range, severe degradation should not be an issue. I've seen a few posts on the forum that try to reference the charge/discharge battery cycle, but it's important not to try and over-simplify from that perspective... the Tesla battery pack is not a single battery cell.