I think they're referring to running out of charge prematurely by using excessive throttle (below 0% SOC) whilst trying to get to a charger, and having the car stall in the middle of an intersection, for example.
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Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health
- Thread starter KK_RedM3
- Start date
LoL-Gas
Member
No, they have mentioned it around 15% or less. I would imagine the software limits any issues but just seeing if anyone here has something productive to add to that topic.
AlanSubie4Life
Efficiency Obsessed Member
You don’t need to worry about it; the car imposes limits on power output at low SOC (and displays the limits clearly).
As with most cars, the less hard you push it, the longer it will last. But that’s just a general rule. In the end, entropy comes for everything, so using the vehicle as intended in the meantime has value.
And my prior post was not tongue in cheek. Below 0%, it is quite possible you will be able to go further without shutdown by being more gentle with the accelerator pedal. (But I have no evidence of this.)
But no need to worry about pack damage. Just plug it in right away.
Lithium polymer batteries used in high demand applications wear much from use below 20% when the power demand is higher than the batteri can deliver.
Lithium ion batteries do not show this at tests, see an example of this in the picture below*)
Tesla limits the power at low SOC so we do not need to limit it further. The power limit can be seen by viewing the pack voltage during full power acceleration. The voltage will not drop too low during full throttle acceleration, this is governed automatically by the car.
*)High power at low SOC is less bad than high power at high SOC. The power demand is seen below each staple as C.
Compare staples at the same C-load (for ecample 2C with 2C staples at other SOC.
2C equals 150-160kW, and 4C 300-320kW.
Just search AAKEE and calendar aging or cyclic aging here on TMC.
Or use google and search for calendar aging + NCA. Read research reports, try to stay out of regular EV websites: many of these was fooled by the myths.
(What I write about is not from a single paper but the sum of more than 100 different research reports.)
Its just as @AlanSubie4Life says.
80-30% is better than 90-40%.
But it does not say that 80-30% is the best in this case if any SOC region was chosen.
51% to 1% would be better for battery health, but not for most drivers' range anxiety.
Well I don't think you really need to worry about pack damage, even going down to 0%, because Tesla keeps a low end buffer (I believe about 3-5%?) even when 0% is the displayed SoC. In fact, most Tesla vehicles can drive about 15-30 miles beyond 0%. But what you don't want to do is allow it to sit for a long period of time starting from 0% because that's when you can cause damage to the pack. Also, I heard of one incident where someone left his Model S at less than 5% SoC after arriving at a hotel late at night, on a cold night. The hotel didn't have a EVSE and he was tired so he decided he'd just visit the nearby supercharger in the morning instead of doing it immediately. The vehicle refused to move in the morning because the battery cooled off and he had to be towed. Oops...
To continue the low SOC end discussion:
This is a picture from a very good research report Panasonic NCA calendar+cyclic aging. It was released 2017.
All cycles ended at 2.5V/ cell. Thats the manufacturers (Panasonic NCR18650PD) lower limit of discharge, which also by definition is 0% SOC.
( And as Tesla use 4.5% bottom buffer this is way below the 0% on the screen and below the limit where Tesla shut down the vehicle because of low SOC.)
Note that this is 4.5% below 0% displayed, and well in the region which people call dangerous
4.20V is 100%
4.10V is about 90%
4.00V is about 80%
My car has an average consumption of 184 Wh/km. One Full Cycle Equivalent would take my car 82000/184 = 445km.
According to the chart above, with 0.5/0.7A which is the closest C-rates to real driving, it would do 625 FCE Cycles, 278.625 km before reaching 20% degradation. This if charged to 100% and driving until the car stops, every time.
If charged to 4.1V/cell (~90%) it would do 800 cycles, or 356.000km. Driven down until it stopped, each time.
If charged to 4.0V/cell it would do 1000 FCE cycles, or 445.000km. Driven down 4.5% below 0% displayed, until the car stops in the ”very dangerous SOC region below 20%”. ( <—- Note, a joke!)
Except for the obvious fact that we can see: low SOC is safe, we also can se that it is the high SOC part that kill the battery despite the misleading name ”deep cycle”.
The deadly part of the deep cycle is in the top.
By not using the top 0.1V/cell or about 90-100% region, we increase the battery life by 25%, in miles.
By not using the top 0.2V/cell or about 80-100% we increase the life 60%, in miles driven.
I guess its clear that a battery that can do 445.000km/ 276000 miles of constant cycling down to 0% is not very badly hurt by this: Cycling (and storing) NCA down to 0% is very safe.
The research report I refer to in this post (link in the beginning) is not the only research report that shows these facts.
There is a lot of reports telling the same thing, this one is a very good read though.
It covers calendar aging as well, cycling cold or hot bstteries etc so if you shpuld read only one report that specifically covers NCA, this is one of these reports.
This is a picture from a very good research report Panasonic NCA calendar+cyclic aging. It was released 2017.
All cycles ended at 2.5V/ cell. Thats the manufacturers (Panasonic NCR18650PD) lower limit of discharge, which also by definition is 0% SOC.
( And as Tesla use 4.5% bottom buffer this is way below the 0% on the screen and below the limit where Tesla shut down the vehicle because of low SOC.)
Note that this is 4.5% below 0% displayed, and well in the region which people call dangerous
4.20V is 100%
4.10V is about 90%
4.00V is about 80%
My car has an average consumption of 184 Wh/km. One Full Cycle Equivalent would take my car 82000/184 = 445km.
According to the chart above, with 0.5/0.7A which is the closest C-rates to real driving, it would do 625 FCE Cycles, 278.625 km before reaching 20% degradation. This if charged to 100% and driving until the car stops, every time.
If charged to 4.1V/cell (~90%) it would do 800 cycles, or 356.000km. Driven down until it stopped, each time.
If charged to 4.0V/cell it would do 1000 FCE cycles, or 445.000km. Driven down 4.5% below 0% displayed, until the car stops in the ”very dangerous SOC region below 20%”. ( <—- Note, a joke!)
Except for the obvious fact that we can see: low SOC is safe, we also can se that it is the high SOC part that kill the battery despite the misleading name ”deep cycle”.
The deadly part of the deep cycle is in the top.
By not using the top 0.1V/cell or about 90-100% region, we increase the battery life by 25%, in miles.
By not using the top 0.2V/cell or about 80-100% we increase the life 60%, in miles driven.
I guess its clear that a battery that can do 445.000km/ 276000 miles of constant cycling down to 0% is not very badly hurt by this: Cycling (and storing) NCA down to 0% is very safe.
The research report I refer to in this post (link in the beginning) is not the only research report that shows these facts.
There is a lot of reports telling the same thing, this one is a very good read though.
It covers calendar aging as well, cycling cold or hot bstteries etc so if you shpuld read only one report that specifically covers NCA, this is one of these reports.
LoL-Gas
Member
If we could start a thread to nerd out on stuff like this, that would be great
That is good data but you have to be careful with it. Remember they stored those batteries for up to 9 months, which is completely unrealistic for most people. Of course if you are going to store your car for long periods, you want to be around 50%.
One thing you can take away from that chart is that high SOC + high temperature is a bad combination. At least Tesla takes care of the cooling to eliminate that problem.
I am looking forward to seeing more real world LFP data in the coming years. So far it seems that LFP degradation is even across the board, regardless of charging habits or environmental conditions - which is somewhat at odds with the chart above. Calendar degradation seems to be a major factor. I would love to see Tesla's internal data, but I guess we will just have to wait and see the user data come in over time.
The tests is done by storing for a couple of months, cycle a few times and measure capacity and then fill it to the test SOC again. Repeat until the test period is done ( 10 months, one or two years etc.)
The researchers seem to see a problem with having it for example nine months with low use.
Calendar aging happens even if the car is used (battery cycled).
The car that is charged to 80-90% and arrives home with 70% will have a calendar aging close to the 75-80% value.
Super long periods and no possibility to charge that seems like a good period.
My car use less then one percent per week so 20-30% covers a very long period, at a lower calendar aging rate.
Absolutely not actually.
Tesla do not cool the battery when the car is parked. The battery assumes the ambient temp and if the var is in the sun the battery psck will be ambient plus 5 degree C or so.
Hot climate is the most degrading factor for a Tesla, specially if not parked in a garage that kerps the temps down.
What happens when cabin overheat protection kicks in? Is it limited only to the cabin?
Also, when I park my car sometimes I hear the condenser coil fans running long after the car was driven, enen though cabin overheat protection is off.
Anyway, I really wish the battery had good insulation and an option to actively keep it at 25C in the hot weather. I'm willing to pay for the extra cost to extend battery life.
Don't know if you are aware of this: might help
Tesla Model 3 and Model Y Battery Insulation
Tesla Thermal Management System Teslas regulate the temperature of the battery and drive unit with a glycol fluid which is heated or cooled as required and circulated through a series of heating/cooling channels and hoses. Insulating the battery and hoses creates a more stable environment which...
evinsulate.com
Most probably only cooling the cabin but i do not know.
Cooling to a temp below ambient needs AC, which would drain the battery and cause extra cycles. Also, if connected to AC power it would cost quite much energy.
Before the heat pump I dont think the car even could cool the battery with the AC (again, I do not know.)
The car does a lot of ”afterwork”. Exactly what can be hard to tell. With heatpump/octovalve it sometimes takes the heat from the cabin and save it in the battery. Anyway, for me the “afterrunning”with fans is not for an extended time.
There is some insulation but its not possible to not get the battery heated by high ambient and the sun. Even with much insulation, in the end, the battery will reach the ambient temperature, and warmer if the sun is doing what it is supposed to do.
We do not need to worry that much. Tesla has taken care of this, and most certain have calculated whats worth in insulation and cooling.
I would say that it is good the know the truth about battery degradation, to have the correct basis before taking any decision about what SOC to use. Instead of doing the same based on myths.
If you know the facts and can not use low SOC, or choose to have 90% each day to get maximum power from a Performance tesla, you did take the decision on facts instead of myths.
Knowing that “I use 90% in a hot climate and I expect to have higher degradation” is s good thing.
Choosing 80% and thinking that that is the optimum SOC and hoping for very low degradation is probably not as good, if you find yourself at 15% degradation after a couple of years.
Im not even worried even one second for people actively choosing 90% because of different reasons as long as they do not think 90% is the best SOC to reduce degradation.
If you have the possibility to have the car at low SOC the hottest days that will do it.
It would be nice to use scan my tesla during active cabin overheat protection to look at battery temps, I wouldnt think the battery is cooled but to be sure.
We need an Australian TMC member with Scan My Tesla and logging.
I cant do it, i live close to the artic circle. I do not have the cabin overheat protection active but even if I had, it probably wouldnt
Don't know if you are aware of this: might help
Tesla Model 3 and Model Y Battery Insulation
Tesla Thermal Management System Teslas regulate the temperature of the battery and drive unit with a glycol fluid which is heated or cooled as required and circulated through a series of heating/cooling channels and hoses. Insulating the battery and hoses creates a more stable environment which...evinsulate.com
I've seen Sandy Munro tear down model 3 and y battery packs and there is minimal insulation. I know a glycol fluid snakes around all cells after being heated/cooled by the AC. Tesla will keep the batteries from getting dangerously hot, but I'm interested in keeping them optimally cool like 25C since I'm in Texas where pretty much every summer day is 40C and much more in the sun.
The point of insulation is not to avoid needing to actively cool or heat, but to do so rarely. Your fridge uses very little power to stay at the optimal temperature because of the insulation. Obviously a fridge without compressor is worthless no matter how much you insulate it has.
I live in Texas where the summer heat is brutal and I rarely charge over 70% and never leave it at high AOC for long, but after 1 year and 18k miles my degredation seems to be about 8%, though I don't think I was ever quite at 100% when I got the car new.
Also for a month and I half in the hottest part of the summer I was out of the country and the car was in the shade and plugged in at a constant 50%.
The last part is my point. The battery pack will adopt ambient temp anyway with more insulation. Even with 2 inch around it wich would make it about 4” thicker (not a nice design in a EV) it would reach ambient temp .
Also Tesla do not cool the pack down to ambient when driving. During hot days it get some 40C (~100F) from highway driving. This means that it either would cool much slower (which increase average temp) or that the car would need to use energy to cool it.
The insulation part is more or less impossible due to the space. Would increase the height of the car. A model 3 would look like Y and Y would be Y^2.
Below is a calendar aging chart for a 2170 NCA battery of ”a brand thst can not be desclosed”.
I have a bunch of Panasonic 2170 NCA of two lots and my preliminary data points to that this chart is for the Tesla 2170 cell or a very closely related cell.
We can see at 80% and 40C it would degrade 8% the first year.
When driving in warm climate the battery gets hot. The same for charging.
And parking in the sun will set the pack at ambient plus 5C (10F) above.
This is another NCA calendar aging chart. It is for the forst 10 months, so for one year it need to be inreased by 10%.
100% is not as bad as most people think. That is a forum myth living its good days.
This can be seen in the charts above. Most
of these research reports of NCA cells show a slight reduction at 100% SOC compared to 80-90% for 25C and colder.
The uppermost chart which I think could be the Tesla 2170 (first version cell, not 2170L) had a much bigger Reduction of calendar aging at 100% SOC then the rest of the research shows, but the rest of the research is on 18650 cells.
My ‘21 M3P has quite low degradation, soon 2 years and now at 54K Km.
I have about 20% Supercharging and have made quite many 100%
Charges (About 1/month in average so 25 or so).
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