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Battery Strategy and Degradation at 10k Miles
- Thread starter gad1976
- Start date
Also might the battery rebalance quarterlyAgree!!!!
I have been conservative since buying the car in February and its gotten me nowhere. A full charge yields 286 miles on a 2023MYP. New was 306. So I lost about 20 miles in range in under a year (13000 miles) despite not using supercharger despite mostly charging to 80 and driving in chill mode. I think each battery pack has its own personality
See YouTube for how to
How did you get 7.5% loss? I am sorry but using the numbers above I get about 4% loss regardless which way I slice them. Thx
Perhaps I answered my own q. Is this right?
PS This is the way to account for 82.1 to 79 "buffer" until BMS kicks in and starts to calculate the loss? I am just trying to understand better the logic behind "Tesla way"
Thx
Thx.About correct!
PS Then above is also true and using the same logic new car EPA is 372 miles. But even Tesla does not want to play at their own game that far LOL
More or less all Teslas have had the “degradation threshold”. 2%, give or take, before the range drops.
This makes up for small differences in capacity and the difference from manufacturing the car until the owner gets it. And also normally a time before the range starts to drop. People get to see the advertised range at least once, and is happy.
Golf8621204
Member
I'm not sure if the member ran the battery degradation test, perhaps they did. But 7.5% does not sound correct for 344 miles of range out of 358 remaining. I understand the calculation - Your taking 4% range loss starting from 79kWh, but if your taking into account the top buffer, you seem to give the bottom buffer a value of 0, meaning the car will come to a dead stop at 0%? Maybe it will, I've personally never done it. I have seen tests that prove otherwise. Suppose his car will still drive 14 miles past 0%? Almost 8% degradation is not even close to being accurate then.
The battery is 82.1 kWh new.
Each mile is worth 221 Wh/km below the degradation threshold.
344miles x 220 Wh/mi = 75.7 kwh capacity.
75.7/82.1= 7.8% degradation.
The initial value can be discussed.
The battery spec in the BMS is 82.1 kWh.
The EPA tests give between 80.7 and 82.1 kWh output with this battery.
I always used 82.1 as the initial capacity.
I once got 82.0 kWh nominal remaining.
No.
Tesla incorporate the buffer in the EPA range. When the car is at 100%, the displayed range incudes the bottom buffer, in the same way any EPA test is supposed to be run until the car stops.
For Tesla, the 4.5% bottom buffer can be driven on. (Which means a 82 kWh battery with 4.5% buffer included in the 82kWh will deliver about 82 kWh in the EPA test.
There is no top buffer. Tesla charges to 100% true SOC and when the battery has better capacity than the degradation threshold, the car still shows the EPA range and each displayed mile (or km) is given more energycontent so the max range stays at the EPA range number.
The buffer is 4.5%, and as long as the BMS not overestimates the capacity, of all possible range driven, 4.5% is below 0% on the screen.
For EPA purposes 16 miles of 358 is below 0% displayed.
colepalmer
Member
This is about average. From what I’ve read, one may expect 10% degradation after 100,000 miles.
What do you think the best practices are to minimize your battery degradation? How much do you care on a scale of 1-10?
Mine are below and I'd scale myself at a 9.
Been reading and listening to what I can on this and its very interesting. In an EV we don't have a gas engine with performance improvements possibilities. There is very little preventative maintenance we can do. But charging is certainly one of those impacts we can control. Many super knowledgeable posters here on the subject, and I also found some great youtube videos such as the link below, as well as many posts of @AAKEE here with his analysis of battery research. This mostly applies to NCA cells (all Tesla except M3 LFP) The conclusions I have drawn personally (which I'm open to hearing all corrections of);
A. Degradation is much quicker in higher temperatures - approaching near zero in very cold winter climates while here in Texas summer being some of the quickest
B. Degradation is lowest at 50-55% SOC (state of charge) or so and under
C. Degradation is thus fastest in high temperature storage at high SOC.
D. Cells change in size depending on the state of charge and this can lead to areas of lithium inside the cells cracking. It's not as bad as it first sounded to me as the cells naturally repair themselves, but this cracking does accelerate the aging and degradation. Thus doing four charges of 35-55% would have less cracking than a single charge of 10-90%.
D. The difference in degradation between storing cells at 80% state of charge and 100% state of charge is quite minimal and a common myth. There is a very large difference in storing at 50-57% range and 80-100% range though.
E. Storing at higher SOC can lead to increased internal resistance, increasing the most at 100% SOC. This especially could be noticeable in performance vehicles losing HP.
F. Battery degradation even at some of these extreme poor practices may allow vehicles to function perfectly fine for 200-300k+ miles. So its questionable how important these practices are to everyay vehicle owners that normally change cars in under 100k miles.
This has lead me to consider having my sort of charging "protocol" as something like this;
1. Keep the SOC at 50% when storing the vehicle, especially during warm periods such as summer travels. I'd consider less but don't know of a way to set that lower with a Tesla.
2. Aim to charge daily, to minimize the frequency of lithium cracking by doing many small charging sessions as opposed to infrequent large sessions
3. Aim to have SOC just simply at 50% daily (Tesla minimum) when only doing around town trips
4. For days with more driving, set scheduled charging to complete in the morning just prior to departure for whatever range is needed that day up to 100%. This gives full range needed but minimized the time the battery is stored above ~55% charge.
5. Aim to store car in cooler place or in AC garage if possible, especially in summer.
6. Do the above practices with the idea to minimize degradation if I keep the vehicle 100-400k miles, and just because I love taking care of my cars. But recognize its a bit of an extreme practice so don't be too strict where it reduces the fun of owning the vehicle or impacts more important areas of everyday life.
Mine are below and I'd scale myself at a 9.
Been reading and listening to what I can on this and its very interesting. In an EV we don't have a gas engine with performance improvements possibilities. There is very little preventative maintenance we can do. But charging is certainly one of those impacts we can control. Many super knowledgeable posters here on the subject, and I also found some great youtube videos such as the link below, as well as many posts of @AAKEE here with his analysis of battery research. This mostly applies to NCA cells (all Tesla except M3 LFP) The conclusions I have drawn personally (which I'm open to hearing all corrections of);
A. Degradation is much quicker in higher temperatures - approaching near zero in very cold winter climates while here in Texas summer being some of the quickest
B. Degradation is lowest at 50-55% SOC (state of charge) or so and under
C. Degradation is thus fastest in high temperature storage at high SOC.
D. Cells change in size depending on the state of charge and this can lead to areas of lithium inside the cells cracking. It's not as bad as it first sounded to me as the cells naturally repair themselves, but this cracking does accelerate the aging and degradation. Thus doing four charges of 35-55% would have less cracking than a single charge of 10-90%.
D. The difference in degradation between storing cells at 80% state of charge and 100% state of charge is quite minimal and a common myth. There is a very large difference in storing at 50-57% range and 80-100% range though.
E. Storing at higher SOC can lead to increased internal resistance, increasing the most at 100% SOC. This especially could be noticeable in performance vehicles losing HP.
F. Battery degradation even at some of these extreme poor practices may allow vehicles to function perfectly fine for 200-300k+ miles. So its questionable how important these practices are to everyay vehicle owners that normally change cars in under 100k miles.
This has lead me to consider having my sort of charging "protocol" as something like this;
1. Keep the SOC at 50% when storing the vehicle, especially during warm periods such as summer travels. I'd consider less but don't know of a way to set that lower with a Tesla.
2. Aim to charge daily, to minimize the frequency of lithium cracking by doing many small charging sessions as opposed to infrequent large sessions
3. Aim to have SOC just simply at 50% daily (Tesla minimum) when only doing around town trips
4. For days with more driving, set scheduled charging to complete in the morning just prior to departure for whatever range is needed that day up to 100%. This gives full range needed but minimized the time the battery is stored above ~55% charge.
5. Aim to store car in cooler place or in AC garage if possible, especially in summer.
6. Do the above practices with the idea to minimize degradation if I keep the vehicle 100-400k miles, and just because I love taking care of my cars. But recognize its a bit of an extreme practice so don't be too strict where it reduces the fun of owning the vehicle or impacts more important areas of everyday life.
Why you have given in completely to the FUD that's out there.
Let's start with your degradation information. sure, doing this vs doing that may change the degradation, but by how much? It's really not that much and over the life of the battery, it's a lot less than people think. And no matter what you do, the difference really isn't that much. AAKEE shows that in his graphs. it's not 30%, it's not 20%. It's barely 10% and that the difference of the age of battery before failure isn't that big at all.
When do you "store" your vehicle? If you are talking anything less than a few months, that's not storing.
Why not follow Tesla's guidance? They designed the car and the battery to take care of itself. They have a lot of highly trained people doing a lot of work to make sure that the batteries work their best. They are constantly monitoring the performance of the batteries on the cars. The do a lot more than the armchair quarterbacks that you hear on the forums. The car will let you know when you are doing something that's not the best for the battery.
Always remember that YouTubers tend to have one thing on their mind, views, it's not truth.
I care significantly about my battery. Elon indicated a few year ago that the batteries were on target to hit their 300,000 mile anticipated life. VERY few cars ever get that far.
Let the engineers who make the big money take care of it. Just charge the car to the Tesla recommended daily number for the specific battery and enjoy the car. I'm 5+ years on my Model 3 and still happily driving down the road.
And I dare say that you still may have a fair amount of range anxiety, (since that's pretty much what battery life is). As you get over it, you start to realize that range really isn't that important anyway. These days there are really so few places where it makes a difference.
And just as an example, let's say that your battery degrades badly, you still are going to have more than a standard range car does.
Don't forget to consider the wear and tear on the Tesla Model Y when you stomp down on the go pedal. Also, all modern electronics are manufactured using lead-free solder. Lead-free solder develops micro cracks over time. Repairing and or obtaining replacement components will be difficult if not impossible so you might as was well enjoy your Tesla vehicle to the fullest while you can.
I don't think that there is much in the power transmission path that is soldered. Solder can't handle the heat and current. Most of it is mechanical mating and welding.
E90alex
Active Member
Anytime the HV contactors are open, the batteries are technically being “stored”. Storage just mean reserving for future use. That “future” can be anywhere from minutes to years. There is no minimum time limit that defines storage.
Teslas recommendations have to balance user convenience with battery lifespan, they are not necessarily the best practice depending what your goals are. And they recently have been changing the recommendation from 90% to 80%. Does that mean their data is showing faster degradation than expected? Were the original engineers that set the 90% limit wrong?
Also if you don’t care, then don’t care. That doesn’t make the information and data FUD because you don’t believe or care about degradation. Let the people that do care do what they want. Other people charging their car to 50% has absolutely zero effect on the range of your car or your cars usability. 10% may be insignificant to you but may be significant to someone else. They are not harming anyone or anything by doing so.
In this concept, that's not correct. In battery talk, "stored" is extended period of not being used, that period being months.
They have now collected more data on specific batteries. (Of which they have more than ANYONE else). and have decided in some instances that there may be better optimizations. But unlike anyone else, they are using very specific data for very specific cases to make the recommendation. They aren't using 10 year old studies to come to conclusions. They aren't using evidence from a few hundred batteries. It's always fun looking at AAKEE's results where it so obvious that he doesn't have enough data, that lines aren't smooth.
It absolutely causes FUD.
With some of the data that is put out there, people Fear that batteries are going to have a premature death. But only a handful have an idea of just how long their battery is supposed to last. Oh know, if I don't do this, it's going to degrade 10% faster? So what does that mean I ask, "I dunno"
As you seem to maybe do, they doubt that Tesla's right!
Data doesn't have to be wrong to cause FUD, it's like me telling you not to eat oranges because they have acid in them. OMG, that means that I'm going to melt if I eat an orange? Does that mean I'm going to die an early death?
Instead of making driving an EV an enjoyable experience, all this does is worry people. And honestly, so very little of what they do, is going to make a difference int he battery life.
Just the other day I say a thread "Tesla had to replace my battery at 20,000 miles" and the poster started worrying about what they did wrong to cause the replacement. They were worried that something that the had done caused the battery to die early.
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