Preference of LFP vs NCA for hot areas (like Phoenix)?

[kevroc]

Debating between the RWD vs AWD and wanted to see if anyone had insight into battery longevity based on temps if living in a high heat area?

I do like the extended range of the AWD, however based on degradation and charging recommendation does it really have extended range? And if so, for how long until they are equalized? Those are really rhetorical questions...

Longevity is my primary concern and I was leaning towards the RWD just for increased cycle life of battery and hopefully a slower degradation rate.

With everything within my control as in charging practice, etc. I really can't control the heat and wanted to see if anyone had insight into how LFP vs NCA hold up to higher temps.

Thanks!!

 

[kevroc]

This is the most interesting data I've found so far regarding it.

"For example, previous reports on cycle aging of LFP cells indicate a tipping point at temperatures of 5 °C–10 °C, with degradation rates increasing both above and below this temperature.26 Studies of LFP cells that considered temperatures only above 20 °C observed the capacity fade increase with increasing temperature (consistent with the present work).27–29 Studies of NMC cells consistently indicate a tipping point around 35 °C. One report found that minimal capacity fade for NMC cells in cycle aging followed 35 °C > 50 °C > 25 °C16and several others found a lower capacity fade rate at 45 °C than 20 °C.17,30 In contrast to LFP and NMC cells, the NCA cells did not exhibit a strong temperature dependence in the range of 15 °C to 35 °C (Fig. 3c)."

 

[Regaj]

Great question. Most everything I've seen tends to lump all lithium-ion chemistries under the same umbrella. But with LFP's resilience to voltage stress (and, hence, the ability to routinely charge to 100%) and the minimal cycling degradation that occurs relative to other LI chemistries, it begs the question if LFP also is also less susceptible to heat-related degradation.

FWIW, I was (and am) deeply intrigued with LFP for all those longevity reasons. Enough so, that I was inclined towards the RWD Model 3. I eventually ordered the LR AWD trim as much because of the extended wait intervals for the RWD, as anything else. But having received the AWD version, I can say that my favorite thing about the whole car - by a mile - is something that wasn't even on my radar screen in the run-up to delivery... its astounding performance. There's probably a hint of confirmation bias buried in that, but there's also no question that, having eaten from the apple, I can never go back to a single motor. The only question now is whether to drop another two grand for the acceleration boost.

YMMV, of course. I have no doubt the RWD is a fine car.

Again, great question. I hope some of the experts here have some answers.

 

[kevroc]

Great question. Most everything I've seen tends to lump all lithium-ion chemistries under the same umbrella. But with LFP's resilience to voltage stress (and, hence, the ability to routinely charge to 100%) and the minimal cycling degradation that occurs relative to other LI chemistries, it begs the question if LFP also is also less susceptible to heat-related degradation.

FWIW, I was (and am) deeply intrigued with LFP for all those longevity reasons. Enough so, that I was inclined towards the RWD Model 3. I eventually ordered the LR AWD trim as much because of the extended wait intervals for the RWD, as anything else. But having received the AWD version, I can say that my favorite thing about the whole car - by a mile - is something that wasn't even on my radar screen in the run-up to delivery... its astounding performance. There's probably a hint of confirmation bias buried in that, but there's also no question that, having eaten from the apple, I can never go back to a single motor. The only question now is whether to drop another two grand for the acceleration boost.

YMMV, of course. I have no doubt the RWD is a fine car.

Again, great question. I hope some of the experts here have some answers.

Thanks for the reply.

I am heavily leaning towards the LR simply for the dual motor, AWD and that sweet premium stereo. Also, I have rationalized that I would just consider the LR a standard range assuming I'm charging to 80% but I'm picking up faster recharge speeds being able to charge to 80% versus 100% for LFP (for the same range) while on the road. All of those things make the price difference of the LR more than bearable.

But man, the life of the battery thing is kind of killing me. I've estimated that I need to get 3,000 cycles out of the battery based on the driving I want to do. Now, that's using a very cloudy crystal ball to be sure, but that's all I have to go on. I think there's a chance I could get that out of the NCA battery based on what I've read keeping the DOD to 60% (Charging 20-80 basically) and that meets my needs. But that seems so outside the 1,500 cycles that seems to be conventional wisdom that I'm not sure that really makes sense. But then you throw in the heat factor and it seems like wanting to achieve a high cycle count out of the NCA is a pipe dream. I know the LFP can do the cycle count I need based on everything I've read, but if the NCA can do it I would definitely prefer that route.

The good thing about performance, going from a 20 year old ICE car to ANY Telsa is probably going to be the same for me

 

[Rocky_H]

But that seems so outside the 1,500 cycles that seems to be conventional wisdom that I'm not sure that really makes sense. But then you throw in the heat factor and it seems like wanting to achieve a high cycle count out of the NCA is a pipe dream. I know the LFP can do the cycle count I need based on everything I've read, but if the NCA can do it I would definitely prefer that route.

You seem to have been talking to some very pessimistic people. It's hard to figure based on this cycle count you are talking about, but there have been a lot of Teslas that have done several hundred thousand miles on the NCA battery packs.

 

[kevroc]

You seem to have been talking to some very pessimistic people. It's hard to figure based on this cycle count you are talking about, but there have been a lot of Teslas that have done several hundred thousand miles on the NCA battery packs.

From what I understand, Musk is quoted as saying the batteries are good for 1500 cycles. That also jives with a chart I saw that said 10-90 charging will result in 1500 cycles before significant degradation. So those 2 things agree with each other and I've seen numerous high mileage posts to believe that is probably true. Where the complication comes in is that most of what I've read is from shorter term (like 1500 cycles could be done in 5 years doing 1 per day). If I plan on attempting to keep the car for 20 years, I have to take calendar aging into account and then the heat factor amplified over that long duration. So when I look at those additional factors, I'm thinking maybe if there is a significant difference between which battery can outlast the other I should prioritize based on the battery and not car features per se. Unfortunately finding clear information isn't really thing because we don't have much real world information. The only thing I keep leaning on also is this "million mile battery" that seems to be LFP based so maybe the LFP does have a better long term life potential than the NCA.

 

[jjrandorin]

But man, the life of the battery thing is kind of killing me. I've estimated that I need to get 3,000 cycles out of the battery based on the driving I want to do.

You need 3000 cycles out of the battery based on the driving you want to do? A cycle is 100-0 back to 100 = 1 cycle. For the sake of easier math (math isnt my strong point)

Lets assume you drive 50% of the battery daily, every day, 365 days a year. A model 3 standard range is rated for 267 miles. So, lets assume you need 50% of that daily, to make the cycle count easier. 133.5 miles daily X 365 days a year = 48,727 miles a year. 365 days a year divided by 2 (50% battery use daily would be 100% every two days, again for trying to make the math easier for myself) = 182.5 cycles a year.

So...

50% cycle daily = 133.5 miles a day
133.5 miles a day, 365 days a year = 48,727 miles per year
50% cycle daily = 1 cycle every 2 days = 182.5 cycles a year.

You say you need 3000 cycles

At the above rate of 182 cycles a year (48k miles), that would be 16.4 years (not counting degradation etc, trying to make the math a bit easier).

In effect, you are saying "I drive 50 thousand miles a year and I need to get 16 years out of this car".

Now, I said math isnt my strong suit, and I am not trying to be funny or anything. Since it sounds like you already did some research and calculated "I need 3000 cycles out of the battery based on the driving I want to do" what was that number? My point is, its unlikely you actually need 3000 cycles, or, if so, the car is likely going to be in fairly rough shape if you drive 50k miles a year and try to go 15 years with it.

 

[Rocky_H]

Yeah, you did the math right. I was already thinking that but didn't go into it. This sounds like someone who thinks a "cycle" is every time there is a charging event, which is not how battery cycles are defined. It is an entire usage of the whole capacity of the battery, which would go to several hundred thousand miles with 1,500 cycles.

The other thing about those battery studies is that they have to set a cutoff point of where they define a battery as done or end of life, because they don't usually just instantly stop. That end of life definition in those studies is degraded to I think 70 or 80% of its original storage amount.

 

[jjrandorin]

Yeah, you did the math right. I was already thinking that but didn't go into it. This sounds like someone who thinks a "cycle" is every time there is a charging event, which is not how battery cycles are defined. It is an entire usage of the whole capacity of the battery, which would go to several hundred thousand miles with 1,500 cycles.

The other thing about those battery studies is that they have to set a cutoff point of where they define a battery as done or end of life, because they don't usually just instantly stop. That end of life definition in those studies is degraded to I think 70 or 80% of its original storage amount.

I thought the same thing (perhaps the OP thinks a cycle is a charging event), but when I read what they said, they said:

That also jives with a chart I saw that said 10-90 charging will result in 1500 cycles before significant degradation.

Where the complication comes in is that most of what I've read is from shorter term (like 1500 cycles could be done in 5 years doing 1 per day)

If I plan on attempting to keep the car for 20 years,

which made me think that:

1. They plan to keep the car 20 years
2. they know that 10-90 is a typical charging cycle
3. 1 cycle a day for 5 years would be 1825 cycles, in line with the 1500 cycles could be done in 5 years comment

So, the above made me think they were aware that a cycle was 100-0-100. Definitely an assumption on my part, though. I was trying to decide if I wanted to move this into the "LFP battery" discussion thread, but decided it was a different enough question to stand on its own.

 

[kevroc]

I appreciate your replies. I'm trying to get my head wrapped around all of the numbers going into this.

I am loosely interpreting (incorrectly obviously) a cycle as a charging event.

I do plan to keep the car 20 years, that's my goal anyway.

I am trying to take into account
1) normal degradation of 10%
2) only charging to 80% (for fast charging at superchargers)
3) not letting it go below 20%
4) a 25% reduction factor I've seen for highway driving at 80mph

My question really is how does heat play into the battery aging and is LFP better or worse than NCA?

Maybe the cycle count isn't an issue, but if it isn't a factor then why is that one of the things I hear being touted when comparing LFP to NCA?

It's all just so confusing and I feel like I'm trying ot rush through an analysis and learn a bunch of stuff trying to buy the right "version" of car. A bit crazy it seems but I'm naturally inclined to overcomplicate a decision so there's that too!

Thanks again for your input.

 

[jjrandorin]

I appreciate your replies. I'm trying to get my head wrapped around all of the numbers going into this.

I am loosely interpreting (incorrectly obviously) a cycle as a charging event.

I do plan to keep the car 20 years, that's my goal anyway.

I am trying to take into account
1) normal degradation of 10%
2) only charging to 80% (for fast charging at superchargers)
3) not letting it go below 20%
4) a 25% reduction factor I've seen for highway driving at 80mph

My question really is how does heat play into the battery aging and is LFP better or worse than NCA?

Maybe the cycle count isn't an issue, but if it isn't a factor then why is that one of the things I hear being touted when comparing LFP to NCA?

It's all just so confusing and I feel like I'm trying ot rush through an analysis and learn a bunch of stuff trying to buy the right "version" of car. A bit crazy it seems but I'm naturally inclined to overcomplicate a decision so there's that too!

Thanks again for your input.

Well....

A "cycle" is 100-0-100. From what I have seen, I believe 10 charges of 10% might be "slightly" better than 1 charge of 100-0. You are not going to do that anyway (100-0), and both are "1 cycle".

Its entirely possible to get "analysis paralysis" trying to min max all this stuff, and some people enjoy that, but it isnt necessary to drive the car. Speed kills (EPA) range, and the "range" number on these cars is at EPA speeds which is 48 miles per hour.

There is a pretty big difference in "keeping it under 80" and "keeping it under 70" for example. With that being said if one goes into it not expecting to get the epa range, and just drives it like a normal car, thats likely the best way to go unless you enjoy trying to "min max".

We dont know if model 3s are going to get throttled at superchargers or not yet. Perhaps someone else has seen posts of that. I dont supercharge other than the rare time I go somewhere outside the range of my car, so dont care too much about that topic.

Planning on driving this car for 20 years, to me, is like planning to use a smartphone for 20 years. In 20 years I would think that you would likely have replaced the battery at least once, so none of this is going to matter, if you drive an "average" number of miles, like 12k miles a year.

 

[3sr+buyer]

Here is a paper comparing degradation of LFP (used in Model 3 RWD), LNMC (used in many non-Tesla EVs), LNCA (used in Tesla EVs other than those with LFP batteries):

ShieldSquare Captcha

iopscience.iop.org

This appears to be where you got the temperature-related quote from. It contains this image:

Note that, under all temperature and discharge rate conditions, LFP batteries can do far more effective full charges (EFC) with more discharge energy than LNCA batteries before degrading to 80% capacity.

While the LFP batteries performed worse at higher temperatures, they will handily beat the LNCA batteries in longevity at those higher temperatures.

 

[3sr+buyer]

Note that worst performance of LFP batteries in that paper was at high discharge rates (3C). 3C for a Tesla Model 3 RWD with a 60kWh battery would be like 180kW, or 240hp. Imagine draining your car's battery with the accelerator on the floor the whole time to approximate that rate of discharge.

 

[Jeremy3292]

Enjoy the read, lots of good info:

Calendar Aging of Lithium-Ion Batteries

 

[kevroc]

Well....

A "cycle" is 100-0-100. From what I have seen, I believe 10 charges of 10% might be "slightly" better than 1 charge of 100-0. You are not going to do that anyway (100-0), and both are "1 cycle".

Its entirely possible to get "analysis paralysis" trying to min max all this stuff, and some people enjoy that, but it isnt necessary to drive the car. Speed kills (EPA) range, and the "range" number on these cars is at EPA speeds which is 48 miles per hour.

There is a pretty big difference in "keeping it under 80" and "keeping it under 70" for example. With that being said if one goes into it not expecting to get the epa range, and just drives it like a normal car, thats likely the best way to go unless you enjoy trying to "min max".

We dont know if model 3s are going to get throttled at superchargers or not yet. Perhaps someone else has seen posts of that. I dont supercharge other than the rare time I go somewhere outside the range of my car, so dont care too much about that topic.

Planning on driving this car for 20 years, to me, is like planning to use a smartphone for 20 years. In 20 years I would think that you would likely have replaced the battery at least once, so none of this is going to matter, if you drive an "average" number of miles, like 12k miles a year.

The Arizona Freeway speeds are 75, doing 80 is pretty routine. That's only about 1/2 the driving though.

The reason for diving into the numbers so deeply is wanting to understand how to best prolong the life.

For instance, if the quote "Current battery modules should last 300k to 500k miles (1500 cycles)." is to be believed. What's the secret to getting the 500k number versus the 300k number? That's basically what is driving me. Is the difference luck of the battery draw or is it within user control based on how the battery is managed? That's the million dollar question for me.

I'm sure it's a combination of both, but for those parts that are within my control, what are those? As far as I can tell, it's everything that's been covered on these forums as in, charge to 80% (maybe less but you can go more if you need to), don't go below 20% (but you can if you need to occasionally), store at 50% for extended times. Don't supercharge too often if don't have too, high charge rates are also not optimal. Etc, etc.

So I understand it enough to know that those things make sense with regards to batteries in general. I'm really just trying to decide with all of those factors, will that result in getting to the 500k number of the stated possible range where someone that supercharges daily would only get 300k.

Also, is the LFP prone to longer life so I could possibly get a higher number of miles without jumping through as many charging hoops?

I understand most people don't keep their cars that long, so none of this really matters. They just have a "drive it like you need to and don't worry about it". And I'm sure that works just fine.

You bring up another good point; "Replacing the battery"
I'm not opposed to it, and actually have replacing the battery as part of my budget estimate. That's another question though where the point may go to LFP. That's going to be the cost of replacement. If say, 10-15 years down the road the battery needs to be replaced, will LFP be cheaper than NCA to replace? One would assume so given what makes up the battery.

 

[Jeremy3292]

The Arizona Freeway speeds are 75, doing 80 is pretty routine. That's only about 1/2 the driving though.

The reason for diving into the numbers so deeply is wanting to understand how to best prolong the life.

For instance, if the quote "Current battery modules should last 300k to 500k miles (1500 cycles)." is to be believed. What's the secret to getting the 500k number versus the 300k number? That's basically what is driving me. Is the difference luck of the battery draw or is it within user control based on how the battery is managed? That's the million dollar question for me.

I'm sure it's a combination of both, but for those parts that are within my control, what are those? As far as I can tell, it's everything that's been covered on these forums as in, charge to 80% (maybe less but you can go more if you need to), don't go below 20% (but you can if you need to occasionally), store at 50% for extended times. Don't supercharge too often if don't have too, high charge rates are also not optimal. Etc, etc.

So I understand it enough to know that those things make sense with regards to batteries in general. I'm really just trying to decide with all of those factors, will that result in getting to the 500k number of the stated possible range where someone that supercharges daily would only get 300k.

Also, is the LFP prone to longer life so I could possibly get a higher number of miles without jumping through as many charging hoops?

I understand most people don't keep their cars that long, so none of this really matters. They just have a "drive it like you need to and don't worry about it". And I'm sure that works just fine.

The best way to prolong life is keeping the battery at a low SoC (57% max), small DoD (20% or so), use Level 2 charging only (avoid Superchargers), and avoid high temps as best you can. There is also an element of uncertainty in the batteries as some people baby the battery like crazy and still have a good amount of degradation.

I'm sure @AlanSubie4Life and @AAKEE could provide some thoughts also.

 

[kevroc]

Here is a paper comparing degradation of LFP (used in Model 3 RWD), LNMC (used in many non-Tesla EVs), LNCA (used in Tesla EVs other than those with LFP batteries):

ShieldSquare Captcha

iopscience.iop.org

This appears to be where you got the temperature-related quote from. It contains this image:

Note that, under all temperature and discharge rate conditions, LFP batteries can do far more effective full charges (EFC) with more discharge energy than LNCA batteries before degrading to 80% capacity.

While the LFP batteries performed worse at higher temperatures, they will handily beat the LNCA batteries in longevity at those higher temperatures.

Yes, and that's also where my "cycle count" fear began...

This graph shows that while NCA "can" get 1500 cycles, that's not the norm.

But then I see an article with this table that shows how cycle counts can change with reduced DOD.

 

[Jeremy3292]

Yes, and that's also where my "cycle count" fear began...

This graph shows that while NCA "can" get 1500 cycles, that's not the norm.

View attachment 782082


But then I see an article with this table that shows how cycle counts can change with reduced DOD.

View attachment 782084

You are misinterpreting the graph. The battery doesn't just stop working at 1500 cycles. The graph is showing the remaining full capacity of the battery (as compared to original capacity). You will notice the the graph stops at 80% of the original capacity. So you can easily get 1500 cycles out of the battery, the question is how much degradation will there be.

And yes, lower DoD (in theory) increases the # of cycle counts. You also must take into account the LFP battery has less energy available. So while the LFP battery may withstand more cycles, those cycles are taking you less miles around town than a similar cycle with an NCA battery.

 

[Rocky_H]

These aren't bad questions.

I understand most people don't keep their cars that long, so none of this really matters. They just have a "drive it like you need to and don't worry about it". And I'm sure that works just fine.

I also plan to keep my car for 20+ years. I have a 2014 Model S, so it obviously has the NCA battery. I knew more of the general things like not sitting at extremely low or high states of charge for a long time. Some of that more recent data I've been seeing from people here about keeping the car really near 40 or 50% to be most ideal sounds fine on paper, but I'm just not going to do that, because it's kind of an annoying and impractical way to use my car. I think this is where the 80/20 rule in life applies to this as well as most things. I am getting a reasonable amount of benefit by doing what is mostly good and avoiding the worst case treatment of the battery. That is good enough without having to stress and worry about it all the time.

And my wife and I recently had a talk about battery replacement or car replacement. With wk057 coming out with the battery warranty plans for older cars, we talked about should we get that warranty? Should we sell this car while it still is working perfectly before the battery fails? We came down to that I really love how this car is. It is grandfathered into the permanent data plan and permanent Supercharging. And we are going to keep it for as long as we possibly can, so we will just go with whatever comes--not get the warranty and probably just do a replacement whenever it happens. And we decided to go with the other way--keep this 2014 Model S and replace the old 2005 Honda Civic Hybrid with a new Model Y.

 

[kevroc]

You are misinterpreting the graph. The battery doesn't just stop working at 1500 cycles. The graph is showing the remaining full capacity of the battery (as compared to original capacity). You will notice the the graph stops at 80% of the original capacity. So you can easily get 1500 cycles out of the battery, the question is how much degradation will there be.

And yes, lower DoD (in theory) increases the # of cycle counts. You also must take into account the LFP battery has less energy available. So while the LFP battery may withstand more cycles, those cycles are taking you less miles around town than a similar cycle with an NCA battery.

I understand they don't just stop working, but since the rate of degradation once it reaches that magic number is not linear, you might as well consider it EOL for estimation purposes.

I'm trying to learn if I can control the rate of degradation meaningfully by adopting the best charging habits. So, determining what are the best charging habits and how do those correlate to between the NCA and LFP (are they the same) and lastly, does the AZ heat affect either of those differently.

And you hit the nail on the head wrt cycles on LFP's. Is that why LFP cycles counts are touted over NCA because they know you'll NEED more cycles due to the lower capacity battery? OR, do NCA's really degradate faster than LFP's so after a few years they are really the same capacity battery?