Engineering Explained: Best practices tips to slow down LFP Battery degrading & extend SOH life

[Grumpy2]

If you have pointers to studies that can answer that question, it will be helpful.

This chart is published at https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

This study using 1C charge and discharge speeds included two at 10% DoD, two with 50%, two with 60%, and one with 75%. This report indicates the closer you stay centered at 50% and away from 100% is best. Also, MickyAO reported staying above 20%, especially at higher temperatures is a good plan.

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[Maxx]

This chart is published at https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

This study using 1C charge and discharge speeds included two at 10% DoD, two with 50%, two with 60%, and one with 75%. This report indicates the closer you stay centered at 50% and away from 100% is best. Also, MickyAO reported staying above 20%, especially at higher temperatures is a good plan.

Thanks. This study like any other I have seen compares different cases at fixed DOD+SOC which does not address my question. My question involves comparing degradation between variable and fixed. For example for the following cases:

1 - Fixed DOD (20%) variable SOC (EX: 30-50, 40-60, 50-70)
2 - Fixed DOD (20%) Fixed SOC (40-60)
3 - Fixed DOD (40%) Fixed SOC (30-70)

Of course this being all cases having the same cycle.

Basically I am curious when it comes to cracking, do the little buggers in number 1 crack as bad as number 3 or as good as number 2.

 

[Maxx]

Although I have not seen anything definitive on the storage aspect.-ie. are they talking about a week, two weeks, a month, six months or a year?

I am not big on taking instructions like that. I like to know how things work so I can decide on my own. This is one of those things in life that is not binary (5 months at 100% is perfectly OK but for 6 month storage you have to be exactly at 50%). Let me put it this way, food that has been sitting in the fridge for one day is less bad than the one that has been there for two days. You will survive eating both but it is good to know which one is better. The longer you keep your battery close to 50%, the better, even if you never store the truck. The difference may be a few % SOH after 20 years and most of us may no longer own the truck by then but it is always good to know. In my case keeping it close to 50% has no appreciable risk or inconvenience. In the past year and a half, I have never had to use the battery to run the house due to power failure more than 10% SOC and if I ever do, I have access to multiple DCFCs in every direction. If I have to take an unexpected cross country trip at a moment notice, we have an ICE and again, there is Tesla Adapter. So even if I never store the truck, I always keep it close to 50% without any appreciable risk or inconvenience.

 

[VTHokies]

ABC…. Always Be Charging…. I keep mine at 85% and always plug it in when I get home, believe that was the recommendation (or close to it) that MickeyAO had.

 

[roddiaz1]

I believe 85% was the early recommendation. More and more I’m seeing recommendations for 80%. Not sure that will make a huge difference in the larger picture, but I dialed back from 85 to 80 a few months back.

 

[OpenMinded150]

*oh ****, here we go again meme*


I charge to 85% and plug in whenever I can. Nothing will change my mind except something peer-reviewed and specific to my year F150 Lightning.

I charge to 90% every day bc I usually need the capacity. I have 59,000 miles on my 23 lightning and still getting 2.4m/kw on county roads this summer

 

[Ishkatan]

I think the 80% recommendation is from talking heads that observed that the truck slows down charging above 80%. When doing a road/distance race charging to 80% and driving to the next fast charger is faster than waiting to 100%. Longevity studies probably fed the charging computers in the truck and are very interesting.
80% fits in with the "don't fully charge" pattern nicely so that is also what I do, unless I am planning a 300 mile road trip.

 

[Richie740]

I looked at my VIN and the 8th digit was a "V" but I was assuming that the was because the 7th digit was an "E" identifying it as "EV" for electric vehilce. My 9th digit is a 5 which does really align with this video.

Am I to assume my 2023 is NMC technology because the 8th digit is not a number but rather a V?

I did read online the 2023 Lightnings would start using LFP.

 

[Firn]

Thanks. This study like any other I have seen compares different cases at fixed DOD+SOC which does not address my question. My question involves comparing degradation between variable and fixed. For example for the following cases:

1 - Fixed DOD (20%) variable SOC (EX: 30-50, 40-60, 50-70)
2 - Fixed DOD (20%) Fixed SOC (40-60)
3 - Fixed DOD (40%) Fixed SOC (30-70)

Of course this being all cases having the same cycle.

Basically I am curious when it comes to cracking, do the little buggers in number 1 crack as bad as number 3 or as good as number 2.

The article you are referencing uses a variable SOC, not fixed. They are attempting to determine if we're the cycling happens degrades battery life (it does).

Within the LFP video they also discuss the point of DOD vs SOC. They explicitly did 100%-0% and 4x as many 25% discharges at different SOC. This was done to ensure the total number of cycles is the same, but to determine if big discharges are better or worse than multiple small discharges.

I would try the videos and studies again because I think the information you are looking for is there.

 

[Maxx]

The article you are referencing uses a variable SOC, not fixed. They are attempting to determine if we're the cycling happens degrades battery life (it does).

Within the LFP video they also discuss the point of DOD vs SOC. They explicitly did 100%-0% and 4x as many 25% discharges at different SOC. This was done to ensure the total number of cycles is the same, but to determine if big discharges are better or worse than multiple small discharges.

I would try the videos and studies again because I think the information you are looking for is there.

I don't think we are on the same page regarding my question. Would you mind sharing the time stamp for the video where you believe it answer's my question? Or copy and paste of the part of the article that does that?

To be clear by variable, I mean moving DOD from one SOC range to another for the same battery.

in the example I listed, number 1 would be something like doing
30%-50% and 50%-30% 100 times
Then do 40%-60% and 60% to 40% 100 times
Then do 50%-70% and 70%-50% 100 times all on the same battery

for case number 2 do 40%-60% and 60% to 40% 300 times

for case number 3 do 30%-70% and 70% to 30% 150 times

Then compare degradation. I didn't see anything like this in neither the study you refer to nor the videos. If I missed it, please share exactly where. I understand the references to batteries not liking higher SOC/voltage so 50%-70% may not be as good as 40%-60% but aside from a minor impact, that is an entirely different issue. I am trying to see when it comes to cracking, if the battery sees the first case really as 40% DOD (the same as third case) because the outer boundary of the range is the same. or it sees is like 20% DOD because most of inflation and deflation of electronic balloon happens withing 20%.

If you see an answer to that, please be more specific.

 

[Firn]

I don't think we are on the same page regarding my question. Would you mind sharing the time stamp for the video where you believe it answer's my question? Or copy and paste of the part of the article that does that?

To be clear by variable, I mean moving DOD from one SOC range to another for the same battery.

in the example I listed, number 1 would be something like doing
30%-50% and 50%-30% 100 times
Then do 40%-60% and 60% to 40% 100 times
Then do 50%-70% and 70%-50% 100 times all on the same battery

for case number 2 do 40%-60% and 60% to 40% 300 times

for case number 3 do 30%-70% and 70% to 30% 150 times

Then compare degradation. I didn't see anything like this in neither the study you refer to nor the videos. If I missed it, please share exactly where. I understand the references to batteries not liking higher SOC/voltage so 50%-70% may not be as good as 40%-60% but aside from a minor impact, that is an entirely different issue. I am trying to see when it comes to cracking, if the battery sees the first case really as 40% DOD (the same as third case) because the outer boundary of the range is the same. or it sees is like 20% DOD because most of inflation and deflation of electronic balloon happens withing 20%.

If you see an answer to that, please be more specific.

The LFP video discusses 25-0, 50-25, 75-50, 100-75, and 100-0 and covering the same number of complete cycles. I quickly scanned the NMC video and i believe he had similar information, although not exactly the same numbers, however i did jump through that one quickly.

That covers both DOD and SOC. I don't have the timestamps handy, sorry.

Edit: The lfp videos used different percents than I quoted above. You really have to read the studies and watch both videos.

 

[Maxx]

The LFP video discusses 25-0, 50-25, 75-50, 100-75, and 100-0 and covering the same number of complete cycles. I quickly scanned the NMC video and i believe he had similar information, although not exactly the same numbers, however i did jump through that one quickly.

That covers both DOD and SOC. I don't have the timestamps handy, sorry.

‘Thanks for sharing your thoughts.

 

[Firn]

‘Thanks for sharing your thoughts.

No worries.

No study can provide information on every single situation. It's also reason to have multiple sources of information and to understand the deeper results of the study.

 

[N87]

I looked at my VIN and the 8th digit was a "V" but I was assuming that the was because the 7th digit was an "E" identifying it as "EV" for electric vehilce. My 9th digit is a 5 which does really align with this video.

Am I to assume my 2023 is NMC technology because the 8th digit is not a number but rather a V?

I did read online the 2023 Lightnings would start using LFP.

Can anyone confirm this?
Mine is EV9 (7th, 8th and 9th character)
Is there way to tell whether it is an LFP battery or NMC, as I am pretty sure it is.

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