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Daily charging/topping up the battery (even only to 80%) could be very bad

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Furthermore even batteryunivercity (which seems to me as the ultimate information source in this matter) states: "There is no standard definition as to what constitutes a discharge cycle."

Not sure how anything ending in .com is the ultimate source of information for anything. If you want accurate information, always go to peer-reviewed publications and state-of-the-art textbooks / reviews, so you can understand what experimental / theoretical data actually support for a conclusion. Of course, you have to first be expert in the field so you can critically read existing literature. Very hard to do. I trust that engineers at Tesla know a little bit about batteries, and recommended the correct charging solution for all of us.

While I applaud the wealth of information existent on the web - some of it very good quality - I would never make a decision in my professional life based on said information alone. That avoids me falling over the edge of the Earth too ;)
 
Tesla battery packs use thousands of smaller batteries arranged into "bricks", with onboard charging hardware and external superchargers designed to protect the battery packs.

Unless measurements are done on Tesla battery packs using Tesla charging hardware, it's not clear how relevant measurements would be for the Tesla battery packs.

What we do have is long term usage data on Tesla battery packs - which show a relatively small amount of battery degradation over time - actual data - based on a wide range of battery charging practices - from real owners.

It's possible battery degradation could be reduced by adopting charging practices to optimize battery charging - though, based on the actual data, since long term degradation seems relatively small, the impact of optimizing charging may not be very large.

Based on our experience with our 2013 S P85 (traded in with almost 100K miles), we plan to follow the same charging practice with our 2017 S 100D and 2018 X 100D - by keeping this as simple as possible. Plug in and charge whenever we are at home. Set the charge level to 90%. Only charge above 90% when we need the extra range to reach our destination or next charging stop, and do so only immediately before leaving. And try to keep the charge from going below 10% almost all of the time.

At least that's worked for us so far...
 
It's possible battery degradation could be reduced by adopting charging practices to optimize battery charging - though, based on the actual data, since long term degradation seems relatively small, the impact of optimizing charging may not be very large.

I completely agree with that. My obsessions is not that much about the battery of my car going bad - it is more about finding the general principle, applicable not only to the EVs but to your phone, laptop, tennis ball machine etc....
 
From what I read, 2 factors affect the degradation the most: average SOC and temperature. BMS manages the temperature so we don't need to worry about it (Leaf doesn't, that may be why it lose capacity quickly). We only need to optimize the SOC and keep the average low. It is ok to charge it to 100% as long as you drive it immediately, not keep it at high for long time. For daily use, 100 to 20 (average 60) may be better than 80 to 70 (average 75). if you only need 10%, make it 60 to 50 or even 55 to 45 instead of 80 to 70. If you take a long vacation, set charge limit to 50% and keep it plugged (so that the BMS can cool the battery). I charge to 60% daily and drive to 45%. If I suddenly need longer trip, I go for a quick supper charge. That way I keep average SOC as low as I can.

On the other hand, there is a different damage to the battery with high current (which causes voltage to drop) at low SOC. So at low SOC, drive gently to avoid voltage from dropping too low.

Overall, it might be better to center around 50% instead of going too low.

The model of the battery is kind of like a spring, the more you stretch it (equivalent to more charge), the more energy it has. But if you keep it stretched for long time, it will lose some elasticity. Higher temperature will make it worse. So you want to stretch it and immediately release the energy and keep the average stretch low to keep the elasticity. This is my understanding of the battery based on what I read.
 
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The other factor I see is that people worry about and I think they need to understand is that Tesla software is protecting us from ourselves. Meaning all though we say don't charge to 100% Tesla has done on better and you can't even charge the pack to 100%. I've been using TMspy and the battery even while charge will only charge the cells to 4.195 and this is with the pack at 100%. I currently have one brick that will hit 4.2 and I think this is where my so called degradation of 3% is at. I have a few bricks that will sit at 4.190 and never go any higher because of the one brick saying 4.2. Now once the charge to 100% is done the pack brick voltages will drop to about 4.185-4.190 so I believe we are being way over cautions about this but time will tell. For me I wish they would let us lower the charge current while supercharging if the bays are more than half empty. This would lower the pack temps and have a greater effect on longevity not necessarily degradation, this is just going to happen.
 
I'm afraid after reading this (batteryunivercity.com) I have to reiterate the original claim that frequent shallow "charging/discharging sessions" (75%-65%) are much worse for the battery longevity than moderately deep charge/discharge (75%-25%). Direct conclusion - no more daily plug in (before reaching 30-25% SoC).
This actually comes to confirm (if I'm not mistaken again) the sheet I posted originally. 90.000 EU (energy units) vs 150.000 EU.
It seems that 75%-25% wins.
I'm not seeing the "much worse" part from the graphs. The graph shows the 75% to 65% case retaining the highest state of charge capacity at the end of testing. Why do you consider that "much worse"? The testing ran less energy through that case, but the battery ended in a healthier state.

Furthermore even batteryunivercity (which seems to me as the ultimate information source in this matter) states: "There is no standard definition as to what constitutes a discharge cycle."
Selectively quoting can get you whatever you want, apparently. Let's try the whole thing:

"A discharge/charge cycle is commonly understood as the full discharge of a charged battery with subsequent recharge, but this is not always the case. Batteries are seldom fully discharged, and manufacturers often use the 80 percent depth-of-discharge (DoD) formula to rate a battery. This means that only 80 percent of the available energy is delivered and 20 percent remains in reserve. Cycling a battery at less than full discharge increases service life, and manufacturers argue that this is closer to a field representation than a full cycle because batteries are commonly recharged with some spare capacity left.

There is no standard definition as to what constitutes a discharge cycle. Some cycle counters add a full count when a battery is charged. A smart battery may require a 15 percent discharge after charge to qualify for a discharge cycle; anything less is not counted as a cycle. A battery in a satellite has a typical DoD of 30–40 percent before the batteries are recharged during the satellite day. A new EV battery may only charge to 80 percent and discharge to 30 percent. This bandwidth gradually widens as the battery fades to provide identical driving distances. Avoiding full charges and discharges reduces battery stress."

This is saying that there is not one exact method or procedure which is the one way in which a cycle is done. But a cycle is still generally considered one run through of the full capacity of the battery. Notice the methods they mention between these two paragraphs. Depleting 80% of the capacity down to 20% before recharging is how batteries are frequently used, and it says that then running them down about 15% from full finishes the rest of the cycle, so you get to represent the capacity of the battery in a normal way, without damaging it by going near 0%.
 
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I'm not seeing the "much worse" part from the graphs. The graph shows the 75% to 65% case retaining the highest state of charge capacity at the end of testing.

I think you misinterpret the graph and the underlying remarks.
The state of health is the same in both cases - 90 % battery capacity retention .

To summarize: for 10 % degradation you get:
case 1 - 75%-65% charging "sessions" - 9.000 cycles but only 90.000 EU (energy units)
case 2 - 75%-25% only 3.000 cycles but 15.000 EU - almost double.

It seems to me the case 2 is a clear winner (if you are looking to get most of your battery per % of degradation).
 
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I think you misinterpret the graph and the underlying remarks.
I don't know how much else I can do to explain these graphs to you.
The state of health is the same in both cases - 90 % battery capacity retention .
It is clearly NOT. The different colored lines on the graph are above and below each other and end at different points vertically on the graph. That vertical axis is labeled "1C capacity retention". The 75% to 65% case ends with a state above the 90% line, at approximately 91%. The 75% to 25% line ends below the 90% line, approximately 87-88%.
And the summary statement right under the graph says:
"Charging and discharging Li-ion only partially prolongs battery life but reduces utilization."

It seems to me the case 2 is a clear winner (if you are looking to get most of your battery per % of degradation).
OK, there. Yes, I do agree with that part. By centering the activity around a midpoint state of charge, you can get more energy through it for the amount of degradation.
 
@Rocky_H

The point of discussion was whether we should charge to 80 % (or 90%) every day notwithstanding the SoC (state of charge) of the battery or it is better to discharge to 25% and then to plug in.

If the graph is correct (and if applicable to all type of lithium batteries) - the best scenario (among those on the graph) is clearly 85%-25%.

At 90% capacity retention (i.e. the same SoH) , the 75-65 case has given only 90.000 EU whereas 85-25% has provided 150.000 EU.
 
I've owned Teslas for about 6 years and in that time I've supercharged a lot and also charged daily, often to 100%. If there has been any battery degradation, it's minor.

If you are trying to preserve your car so that in 10 years it has the same capabilities as it had when new, perhaps you should be zealous about how you charge. For most people, though, it shouldn't be a concern. I'd much rather enjoy the car and have it ready for longer trips without the need for stops.
Agree, I keep my 2012 Sig at 70-85% all the time ... no serious functional impact!
 
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@Rocky_H

If the graph is correct (and if applicable to all type of lithium batteries) - the best scenario (among those on the graph) is clearly 85%-25%.

At 90% capacity retention (i.e. the same SoH) , the 75-65 case has given only 90.000 EU whereas 85-25% has provided 150.000 EU.

I meant 75%-25% (not 85%-25%).

And yes I do agree that keeping the car at 75%-80% shows no harm in practice.
I was just wondering how this was possible given the above data.

Again this is not a big deal - I guess we can close the thread now...

Just to be clear I did not add any false information as accused in the beginning of the thread as the sheet columns added by me turned out to be consistent with the above graph + the underlying comments.

Apparently the therm "cycle" is not as clear at some of us might want to think.

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I am a new Tesla 3 owner and this has been useful. At the end of the day I walk away with:

Don’t charge up to 100 percent unless going on a trip
Charge up to 75 percent and ideally run down to 25 percent before charging up for normal weekly use.

Correct everyone??

On another note don’t run your 3 through a car wash with brushes. Car freaked out into park had to shut down wash and slowly drive out. Why not just tell us idiot new owners up front to use brushless wash only?
 
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I have no opinion on the technical merits involved in daily vs more weekly charging. One thing that is missing from the discussion is that over time, the charge frequency tends to increase as the total capacity diminishes. Meaning...new it had 300 miles of range, but at 100,000 miles it has 250 miles of range (only an example). This requires charging more often to make up for the 50 miles of lost range, thus using up 'charge cycles' faster. In sum, its not exactly linear degradation even if the usage remains constant.
Another factor to consider is that one cannot expect to just run the batteries till they will not charge anymore. Like any other battery powered electronic system, there comes a point at which there is not enough minimum voltage in the charge capacity to meet the needs of the circuitry. It like what happens if you try to run a 120 volt computer system on 100 volts. The power supply shuts down as a fail safe.
Hopefully, it will be decade before any of that makes a difference. So far, I am quite satisfied. At 50k miles on a 2014 S85, I am still holding on to 95% of the original range/capacity. I don't expect to become concerned about any cell replacements until it drops below 85%.
 
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I have no opinion on the technical merits involved in daily vs more weekly charging. One thing that is missing from the discussion is that over time, the charge frequency tends to increase as the total capacity diminishes. Meaning...new it had 300 miles of range, but at 100,000 miles it has 250 miles of range (only an example). This requires charging more often to make up for the 50 miles of lost range, thus using up 'charge cycles' faster. In sum, its not exactly linear degradation even if the usage remains constant.
Another factor to consider is that one cannot expect to just run the batteries till they will not charge anymore. Like any other battery powered electronic system, there comes a point at which there is not enough minimum voltage in the charge capacity to meet the needs of the circuitry. It like what happens if you try to run a 120 volt computer system on 100 volts. The power supply shuts down as a fail safe.
Hopefully, it will be decade before any of that makes a difference. So far, I am quite satisfied. At 50k miles on a 2014 S85, I am still holding on to 95% of the original range/capacity. I don't expect to become concerned about any cell replacements until it drops below 85%.

More then likely you will never get there, you'll replace the car and all this talking (worrying) about these issues become just that, talking.

It won't matter, you, all of you, will have moved along most likely and some other lucky soul will be driving your 60, 70, 75, 85, 90, 100 around town pinching himself at how he owns a Tesla and loves it with slightly degraded battery he could not care less about.
 
Charge up to 75 percent and ideally run down to 25 percent before charging up for normal weekly use.

Correct everyone??
No, running it down to 25% before plugging in is not ideal practice. That's a flawed conclusion from this one flawed data point.

Ideal is technically to keep your battery as close to 50% as possible, but you really shouldn't worry about it too much. Best to always make sure you have enough charge to handle unexpected trips.

Say you are sure you only need 10% capacity per day. Then it's better to plug in every day and keep it between 55% to 45% than to run it down from 75% to 25% over 5 days and plug in every 5 days.

Problems I see with the 75%-25% conclusions reached from that one graph:

1. Go to original IEEE paper that it was taken from and you'll see that the authors didn't reach that conclusion, or have those notes below the graph. This is just one example of a Dynamic Stress Test from a single manufacturer for a specific battery.

2. The graph is one manufacturer's results for a specific LMO battery. Tesla doesn't use the LMO chemistry in their batteries.

3. The 90,000 vs. 150,000 EU calculation is simply wrong. The 90,000 assumes that the 75-65% line crosses 90% at 9000 test cycles. The data doesn't go out that far. Maybe it crosses 90% at 15000 test cycles, which would give 150,000 EU. We don't know.

4. If you compare 75-65% to 75-25% at actual known points on the graph, you don't see much difference. Take the 95% retention point. 75-65% crosses at about 3000 test cycles, 75-25% crosses at about 600 test cycles. Both are then equal at about 300 EU.

5. The 75-65% has an average SoC of 70%, while 75-25% has an average SoC of 50%. A fairer comparison would be 55-45% vs. 75-25%.

6. This specific Dynamic Stress Test doesn't necessarily represent real world degradation over time. It also doesn't take into account any benefits of battery conditioning that you'd see by keeping your car plugged in more often.
 
I had a 2011 Nissan Leaf that went from 94% when I bought used to roughly 66% capacity in two years of ownership. Leaf mileage when bought new 16k miles to 43k miles at time of trade in.

I now have a 2013 Toyota Rav4 EV with 93% capacity then to 99% capacity with newer pack (replacement due to bad cells) bought 61k now has 121k and a 2013 Model S with roughly 96% capacity from a 60 kWh pack. Bought with 40k now has 51k miles.

Tesla makes a great pack and you wont have to worry about capacity due to range.