Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?

[Horsefly]

i was would suspect that being that planned obsolesce is a very real thing, manufactures, WANT you to use the cells in a way that will minimize there service life

I don't know if that is true. All the cells are manufactured in China. It seems like there are two layers for us DIYers: The manufacturers and the sellers. The sellers are mostly just interested in transactions. I don't think many of them worry about us coming back for cells to replace the ones we have. They probably all hope to be doing something else by that time. I think the manufacturers don't care a bit about we DIYers, but they do car about the car companies that are buying huge quantities of their cells. One of the things those companies are counting on is the longevity of the cells, so the manufacturers are keen for long-lasting cells just so they can keep selling them more cells, NOT replacement cells.

my goal for both me and others was to have a single source of the best settings and conditions for maximum longevity and minium cell stress

I think what you are doing is noble and probably worthwhile, even though - like you said - there may not be a one size fits all solution. I think we all benefit from the conversation, and you trying to capture it in one place is good.

 

[Go2Guy]

I don't know if that is true. All the cells are manufactured in China. It seems like there are two layers for us DIYers: The manufacturers and the sellers. The sellers are mostly just interested in transactions. I don't think many of them worry about us coming back for cells to replace the ones we have. They probably all hope to be doing something else by that time. I think the manufacturers don't care a bit about we DIYers, but they do car about the car companies that are buying huge quantities of their cells. One of the things those companies are counting on is the longevity of the cells, so the manufacturers are keen for long-lasting cells just so they can keep selling them more cells, NOT replacement cells.

I think what you are doing is noble and probably worthwhile, even though - like you said - there may not be a one size fits all solution. I think we all benefit from the conversation, and you trying to capture it in one place is good.

you are correc i should have said sellers , but still it remains a massive question as to why battle born and others ecomends using 100 SOC% when this goes against common knowledge . . in the FAQ they recomend storing them at 100 SOC . we all know this is wrong, but yet they insist on recomending it. .

Conversely, LiFePO4 (Lithium Iron Phosphate) batteries can be continually discharged to 100% and there is no long-term effect
----------------https://battlebornbatteries.com/faq/

 

[Horsefly]

I have heard (but have no personal knowledge) that Battle Born uses cells larger than the spec to give them room to say something like that. That is, if the cells inside a 100Ah Battle Born battery are actually 120Ah, they could say that 110Ah is 100% and 10Ah is 0%.

Whether that is true or not, it does bring up one of the hardest things about what you are trying to do. For the manufactured (not DIY) LiFePO4 batteries, none of us know what is inside the box, with the notable exceptions @Will Prowse and the YouTube LithiumSolar guy who both seem to rip the things open all the time.

 

[robby]

i spent quite some time reading that graph and doing my best quantify that into tangible statement, but not sure how exactly . . . would you mind summarizing in a way that. seems like great data, but very hard to summarize, i will add it as a link tho

my goal for both me and others was to have a single source of the best settings and conditions for maximum longevity and minimum cell stress. I know its potentially not ideal for all cells . . but i had spent many many hours searching for such a summary and could not find a single compiled source, so after searching for so along i decided gather all the data from others and compiled it. it may not be perfect, but its the very best data i could find for minimum cell stress and maximum cell life. . also I wish for it to a "living document" so in other words as more data is found i will adjust accordingly. Just a question do you now of which cells may have alternate chemistries that you mentioned, how identify that there different and how you alter the charge recommendations for max service, for such cells . . i would be willing to add that data. . .

I applaud the effort, I just felt it was worth mentioning to people that they should not abandoned the company recommendations on pre built packs as this battery tech is a moving target. I just talked to John at Fortress Power 3 days ago and he gave me some updated numbers that they are using at the Lab. As he stated these numbers are in Beta but are showing very good results so far. Battery formulations change and it takes time to know what is optimal for it.

While I agree with "Will" on most things I don't think I will ever agree with him on his 0% discharge stance. If this was closed loop and I knew for sure that a batteries BMS was doing some kind of offset so that 0% was really 10% (which is what the phones and tablets seem to do) then I would be fine with it. The fact that 0% is so close to the lowest voltage the battery can produce as it drops off the capacity cliff. Just makes it a bad idea IMHO.
I think Will has a more casual look on things because he is literally swimming in extra batteries and I have never seen him buy very expensive batteries, the kind that make you think twice about taking chances. Would you buy a $13,000 eVaut Max and use anything other than the manufactorers recommended voltages and currents?

i was would suspect that being that planned obsolesce is a very real thing, manufactures, WANT you to use the cells in a way that will minimize there service life, many have said that these cells can last in theory for decades, however most major manufactures like battle born say go head and use the 100% SOC BUT who is to benefit from this, you or them

I think their main goal is that you get the 10 years out of the battery without losing more than 20% of the capacity. We keep thinking this is some sort of static industry, but it is not. The batteries put in a pack 18 months ago are not the same as the ones put in a pack today. The Ev companies keep pushing the market to move forward faster.

. it doesn't seem there cells are engineered in any significantly different way to allow continuous 100% SOC use will out degradation in service life, AND IF THAT CASE WHY RECOMMEND IT?? , which means IF you were baby the cells IN defiance of there recommendations you would likely double the service life. . BUT again would manufacture actually want to double the service life?? the only pockets that benefits is yours , not theres

100% SOC continuously held has never been a possibility for Lithium technology. If I remember correctly it's because the Dendrites would start to grow in the cell very quickly and then make it useless. Maybe Solid State batteries will solve the issue but who knows if that will really bare fruit.
As for "who benefits". I think we have all gotten a bit to cynical due to the politics of today. I think the companies like the idea of their battery giving you more than what you expected. If I use car startig batteries as an example, the cheap ones may be warrantied for 2 years and I typically find that in 2.5 Years they die or start to become unreliable. Same thing with AGM batteries. One day I bought a Glass Mat AGM battery from Japan that had a 5 year warranty. The battery worked perfectly for 8 years! The ones that last long tend to be the hottest sellers within a market segment that is willing to cough up a bit of extra cash. It would be a disaster for a top tier battery company like Simplihi, Fortress or BYD to have a situation in the future were Packs for half the price like the EG4 or SOK were beating them out in longevity or capacity over time. For expensive established brands it's got to be more about customer satisfaction rather than trying to keep selling them more batteries in a shorter period of time. If not their reputation will be dead in the future.

 

[curiouscarbon]

i spent quite some time reading that graph and doing my best quantify that into tangible statement, but not sure how exactly . . . would you mind summarizing in a way that. seems like great data,

totally agree! formatting makes it so hard to read and understand.

clarity update: this paper only did 100 cycles, keep that in mind when interpreting degradation rate!


Tc is cell temperature while charging
Td is cell temperature while discharging
(people here often have these the same)
So mainly look at rows with DT/C of 0.
Ci is first reference cycle capacity at room temperature. note they are all almost the same of ~5.6 Ah
C1 is first cycle at the temperatures Tc,Td of row. note how cycles in cold temps have low capacity of down to 3.0 Ah at -20/-20 Tc/Td.
Note this capacity loss is reversible by bringing the cell back to room temperature.
CRref is the capacity AFTER all the cycles, but done at the reference temperature to remove the reversible temperature related capacity loss.
DR (Ah/N)Ah is derivation of how much total capacity is lost for a single cycle given the teat temperatures.

be aware that Degradation Rate is for after the 100th (Final) cycle!!

perfect battery will have same capacity for Ci,C1,CRref and would have DR of 0.00

hope this helps!

basically, for super fast reading,

choose your operating temperature. find closest match under Tc/Td. go all the way to the right to see DR or the fraction of capacity lost per cycle at those temps.

remember, this paper only did 100 cycles, keep that in mind when interpreting degradation rate!

edit for clarity

 

[Horsefly]

totally agree! formatting makes it so hard to read and understand.
View attachment 82453

Tc is cell temperature while charging
Td is cell temperature while discharging
(people here often have these the same)
So mainly look at rows with DT/C of 0.
Ci is first reference cycle capacity at room temperature. note they are all almost the same of ~5.6 Ah
C1 is first cycle at the temperatures Tc,Td of row. note how cycles in cold temps have low capacity of down to 3.0 Ah at -20/-20 Tc/Td.
Note this capacity loss is reversible by bringing the cell back to room temperature.
CRref is the capacity AFTER all the cycles, but done at the reference temperature to remove the reversible temperature related capacity loss.
DR (Ah/N)Ah is derivation of how much total capacity is lost for a single cycle given the teat temperatures.

perfect battery will have same capacity for Ci,C1,CRref and would have DR of 0.00

hope this helps!

basically, for super fast reading,

choose your operating temperature. find closest match under Tc/Td. go all the way to the right to see DR or the fraction of capacity lost per cycle at those temps.

The funny thing is, the table says that to minimize the degradation of capacity, charge and discharge at -20°C (-4°F). And yet, we've all been told that charging at that low of a temperature will... ahhh... shorten the lifespan, degrading the capacity. Go figure.

 

[curiouscarbon]

The funny thing is, the table says that to minimize the degradation of capacity, charge and discharge at -20°C (-4°F). And yet, we've all been told that charging at that low of a temperature will... ahhh... shorten the lifespan, degrading the capacity. Go figure.

indeed, their data looks kind of confusing to me, but remember that LiFePO4 cells can exhibit elevated cycle capacity for "early" cycles, suggesting that degradation rate is not the same between cycle 5 and cycle 6 and cycle 3005 and cycle 3006.

i had to spend a *lot* of time reviewing their procedures to make heads or tails of what the chart meant. they describe it really painstakingly, lol

also, remember!! this paper only did 100 cycles. please do not extrapolate to 5000-10000

this is in part because the way the cell degrades is slightly different at the beginning vs the end.

if only they had more funding and could run more permutations for more cycles... ?

 

[chrisski]

Even when it was 100° F outside, my RV trailer (three season at best) was only 85° F inside. The trailer is not under cover. I'm OK with the batteries staying in place at those interior temperatures. @chrisski is in AZ and removes his batteries in the summer when not in use.

I know I said I was going to do this, but I did not.

Last Summer I had lead acid batteries. When it came down to it, I did not climb the ladder to remove the batteries.

This coming summer, I have installed the lithium iron phosphate batteries. I will likely go nowhere with the RV in June - August. Removing the Lithium Iron Phosphate batteries is even harder than the lead acid batteries. 16 Cells installed in 2 batteries with busbars and no way to ligt them out in groups.

I'm not sure what I will do exactly for the lithiums in the summer. They will see 110 F every day they are in storage. I will likely store these at 50%. Taking 16 cells out and putting them in is a lot of work, but for me more importantly every time you take something apart and put it back together risks breaking something. Even if I did, my garage sees the same heat every day, and now I'd be storing them in my entryway of my house. That has its own risks.

If I had the 16 cells in split 8 each in two cases, I may remove them, but now I'd have to have someone help me take them out, and I'm also lacking on volunteers for manual labor. Would also be better if I had a forklift.

 

[curiouscarbon]

The funny thing is, the table says that to minimize the degradation of capacity, charge and discharge at -20°C (-4°F). And yet, we've all been told that charging at that low of a temperature will... ahhh... shorten the lifespan, degrading the capacity. Go figure.

thanks, i've updated the resource itself to include a very clear note that only 100 cycles were done for the testing. this means it's not applicable to 1000's of cycles, but it does provide a look at how temperature of discharge and charge can affect early degradation evolution.

also updated all my recent posts to make it really clear that ONLY 100 cycles were done. hopefully this can reduce the confusion of the results.

also, they could have observed those surprisingly low degradation rates for those temperature combinations as a result of a systematic or methodological error, making it invalid (disclaimer: i read their procedures fully and it was very tedious and it looked pretty darn squeaky clean to me.)

last! and sorry for the double response the battery was HELD at the given temperature by a regulated environment.

plenty of people here store the battery in a non-temperature-regulated space, so these results might mean something slightly different given that a temperature regulated environment will generally dissipate more of the internal heating than a non-regulated one. heat -> degradation. regulated temps -> less heat -> less degradation, is how i would imagine it.

kind regards, and thanks everyone for sharing so much interesting info about this super neat chemistry!

 

[curiouscarbon]

btw that paper used this elecrolyte composition, to help keep comparisons apples to apples

Use 80 g of electrolyte: 1 M LiPF6 in ethylene carbonate:diethyl carbonate (2:3 w/w) containing 1% vinylene carbonate.

any cell using a different elecrolyte mixture would be expected to have potentially VERY different degradation rate over time and temperature

 

[Smokin]

Yall Stupid Man The Battery/cells are what they are, not what you type or think or whatever. They are only what they is. Got IT. Up down UP down Poof. Start over. Get it.

 

[curiouscarbon]

shout out to philtao for this resource about temperature and degradation

it focuses on Calendar Aging vs Temperature more.

Why temperature of lithium cells is important

Temperature is an important parameter that influences the aging of a lithium battery. At 35°C a lithium cell ages twice as fast as it does at 15°C. So if the battery’s useful life is 15 years at 15°C, it will be 7.5 years at 35°C. I summarize...

diysolarforum.com

 

[curiouscarbon]

Yall Stupid Man The Battery/cells are what they are, not what you type or think or whatever. They are only what they is. Got IT. Up down UP down Poof. Start over. Get it.

but i only want to get them once! ? cheers

 

[Horsefly]

Yall Stupid Man The Battery/cells are what they are, not what you type or think or whatever. They are only what they is. Got IT. Up down UP down Poof. Start over. Get it.

Wow. I may need to write that one down, so I can use it myself!

Of course, I'll first have to figure out what it means...

 

[toms]

? Thread full of information derived from testing that doesn’t reflect the reality of low C rate useage of LiFePO4.

I have a set of decade old cells that prove just about every statement made in this thread wrong.

It is chemically impossible to simulate degradation of LiFePO4. The only way to simulate long term low C rate degradation is by using the cell long term at low C rates.

Remember this chemistry has been in use since 2005 - and many cells made then are still in use and returning above 80% capacity.

Yes you can kill the cells easily via various methods, but nobody knows for sure how long they will last under optimised conditions.

I’ll stand corrected if someone can actually find a battery that has been run at optimum conditions (as i have posted on this forum many times) that has fallen below 80% capacity.

 

[Horsefly]

So @toms - This thread is about optimum charge controller settings, and has obviously expanded to other things that can affect the longevity of LiFePO4 cells. It sounds as though you are our most renowned expert on what the "optimum conditions" are. You've got the creds. You gonna make us search the board for those optimum conditions? Wouldn't it be appropriate - in this thread - for you to just tell us all?

 

[Go2Guy]

but i only want to get them once! ? cheers

thats my same belief. . , if in theory these batteries can last decades, them im gonna do my damndest to make that happen, to all those who dont care and have the resources to drop stacks on battereis when ever they want. . . great for you!!!, and this thread isnt for you. but for those of us who this was a substantial once in a lifetime type of purchase, we have every incentive to baby these cells to the max. . it seems the only ones who disagree with motives of this thread are those who have the financial resources to not really care how long they last because they just go buy new ones

 

[Go2Guy]

? Thread full of information derived from testing that doesn’t reflect the reality of low C rate useage of LiFePO4.
. . .
Yes you can kill the cells easily via various methods, But nobody knows for sure how long they will last under optimised conditions.

I’ll stand corrected if someone can actually find a battery that has been run at optimum conditions (as i have posted on this forum many times) that has fallen below 80% capacity.

that really is the goal of this thread. . a single compiled source that lists what parameters are needed for optimized conditions for the longest service life possible ..[tempature got added to the list later because of its massive potential impact on long service life. . i spent 15 hours trying to find this in a single place where i can find the ideal program paramters and it did not exist ANYWHERE ON THE WEB not even this site. . really what i need were raw number to plug into a charge controller for ideal service life. . . . not even battery university listed such info. instead its all technical irrelevant data when all I needed were the raw numbers for bulk/asorb/float/cut off . . remember lead acid is on 50%DOD so any gains over that are substantial

I have a set of decade old cells that prove just about every statement made in this thread wrong.

please let me know what exactly is wrong i will update the first main post.

my goal here really is is accuracy. Also ironically this becoming a peer reviewed post, because every piece of data brought to the table whether for or against the current summary is added to the main post to have it taken into consideration

 

[Go2Guy]

shout out to philtao for this resource about temperature and degradation

it focuses on Calendar Aging vs Temperature more.

Why temperature of lithium cells is important

Temperature is an important parameter that influences the aging of a lithium battery. At 35°C a lithium cell ages twice as fast as it does at 15°C. So if the battery’s useful life is 15 years at 15°C, it will be 7.5 years at 35°C. I summarize...

diysolarforum.com

wow this info is GOLD!!!!!! THANKS!!!!

 

[Browneye]

YOU CHANGED YOUR AVATAR. I was already confused enough.
Yep, good stuff.