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

[Sojourner1]

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?

Post in thread 'New Bank isnt charging past 3.35 each cell' https://diysolarforum.com/threads/new-bank-isnt-charging-past-3-35-each-cell.11035/post-120915

Took 1 minute for a quick search, unless he has changed it.

 

[Browneye]

I think the point is you have to understand what all is going on so you can make adjustments for your own battery pack. They're all going to be a little different, and all have different usage, and consequently settings. You have to figure out what works for you. That can take a little trial and error. Understanding the concepts helps me a lot. Like having balanced cells - if they go over or under volt they shut down your system.

Some users push them harder than others. Some are looking for peak power, some are looking for lower power for long duration.

I don't use my batteries for a microwave. I never liked them things when they were invented. I would much rather use a gas stove. At home or away, it's a blue-flame baby.

 

[Sojourner1]

Go2Guy if you haven't realized it by now you need to pick a voltage that works for you. Many responses and post are parroting responses from others with little longterm use.

The answer you seek will only come in time. Tom's can give you #s that has worked for him for over 10 years. I can give #s that have worked for 6 years. Another will give #s that worked for X amount of years. Only time will give the exact voltage everyone seems to seek. ??

 

[Browneye]

I've been messing with lithium-polymer (lipo) 3S cells for a few years with the RC crawlers - tiny 4x4 trucks 1/10 scale, electric drive motor and servo. Guys end up with thousands of dollars in these things, I'm guilty. But those batteries last and last if you take care of them. Some of them just go poof and give up the ghost. I don't want that to happen to my expensive lifepo4 pack. Same deal with the lithium ion ebikes - just love me some eMTB's - I spent fifteen grand on bikes last year after the covid thing hit. Love them things! If you abuse the pack they don't keep their capacity.

One thing that seems to be common for all lithium type batteries is that they shall not be stored in a 100% state. When you add heat some cells can go over volt and ruins the cell. This is for virtually all battery types. Charge and use - don't store in a discharged or over-charged state. This causes permanent damage.

I put a display meter on my cells for a physical look - I had not messed with BT apps like these have before this project, it's all done electronically/digitally now. That is a new thing for me. I like the GUI - it's easy to gauge what's going on with your cells and charge levels, and you make adjustments accordingly.

Just my 2-cents...if it's off-topic just ignore.

 

[Horsefly]

Post in thread 'New Bank isnt charging past 3.35 each cell' https://diysolarforum.com/threads/new-bank-isnt-charging-past-3-35-each-cell.11035/post-120915

Took 1 minute for a quick search, unless he has changed it.

Sounds like he could just say that, instead of walking in to the room and saying everyone is stupid.

 

[curiouscarbon]

? 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.

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.

hear hear!

It is chemically impossible to simulate degradation of LiFePO4.

I do not believe that this statement is true.

The only way to simulate long term low C rate degradation is by using the cell long term at low C rates.

That's testing?

C rate totally important! I'm planning on hitting my cells with 2-4C at times, at least for discharge, so I don't get the overemphasis on Low-C rate. People with big batteries might only see <0.5C charge or discharge ever, sounds pleasant.

All degradation should be couched in terms of relevant parameters, Temperature, C-Rate, Max Voltage, Min Voltage, Time at Given Temperature, Ampere Hours Charged at Given Temperature, Ampere Hours Discharged at Given Temperature, Time at Given Voltage, Ampere Hours Discharged at Given Voltage, Ampere Hours Charged at Given Voltage, Time at Given Voltage at Given Temperature, Cycles, etc..

Degradation is parameterized by these values. Not any single parameter gives the whole picture, and monitoring all of them does not necessarily give the whole picture either. I argue that it is absolutely possible to log and characterize these cells. All one must do is study the chemistry, collect data, analyze the data, adjust operation parameters.

cheers

 

[curiouscarbon]

Post in thread 'New Bank isnt charging past 3.35 each cell' https://diysolarforum.com/threads/new-bank-isnt-charging-past-3-35-each-cell.11035/post-120915

Took 1 minute for a quick search, unless he has changed it.

I’ve been using the FM80 for DC charging my 20kwh LiFePO4 for the last 7 years.
I use 55.5V bulk, 0.5hour Absorb, 55.3V float, and rebulk at 55.0V

Bulk 55.5 Volts / 16 Cells = 3.46875 Volts per Cell
Float 55.3 Volts / 16 Cells = 3.45625 Volts per Cell
Rebulk 55.0 Volts / 16 Cells = 3.43750 Volts per Cell
Bank 20kWh / ( 16 Cells * 3.2 Volt per cell ) = 390.625 Ampere Hours
Absorb 0.5 Hours / 390 Ampere Hours = 0.0012820512820513 Hours Absorb per Ampere Hour
Absorb 4.6 Seconds of Absorb per Ampere Hour

Multiply your bank's Ampere Hours times 4.6 seconds and divide by 3600 to get how many hours to absorb, to match these parameters.

"How to maximize operational lifetime of LiFePO4 cells by careful selection of Operational Parameters given Local Conditions."

Good luck to everyone seeking to maximize lifetime of their cells! And everyone else too.

 

[Sojourner1]

Sounds like he could just say that, instead of walking in to the room and saying everyone is stupid.

He could of but than when you search some you might just find a vien of gold and harvest some real riches or like many they want the miracle grow poured all over themselves.

 

[curiouscarbon]

Come on, post useful thing, the search is crap and misses lots of thing if the wrong wording is used. Let's give it more to work with.

Posting per cell voltages makes it easier for people to use it with their own system.

Then when people search they'll find it easier

 

[Horsefly]

He could of but than when you search some you might just find a vien of gold and harvest some real riches or like many they want the miracle grow poured all over themselves.

And how does that contribute to this thread?

 

[Sojourner1]

Search and find out.

 

[Horsefly]

Search and find out.

Do you even understand the concept of a "thread"?

 

[Maintenance guy]

GotoGuy: it is basically up to you to decide as you gather all the necessary information the decide for yourself.
but if you set your BMS to stay out of the knee of the curves lowering the balance parameters to reflect this you will be OK.
Me i am setting my Bulk CC to 3.3 to 3.4 then Absorb CV to 3.4 to under 3.5. NO float. setting my Balance at 3.4 to 3.45. LV at 3.1 to 3.15. after i do more test i will have exact parameters. another thing is stay at or below .5 charge/discharge and you will be fine.
it is crazy to think you have to set it at 3.6 to balance. just change the fricking setting in the BMS to reflect lower balancing.

Another thing is head Will's advice keeping your batteries cool in the summer time. study LiFePo4 Lattice structure. I have read almost everything Will talks about concerning Lattice structure. he is correct.

Good luck and Happy LiFePo4 ing

 

[Horsefly]

The answer you seek will only come in time. Tom's can give you #s that has worked for him for over 10 years. I can give #s that have worked for 6 years. Another will give #s that worked for X amount of years. Only time will give the exact voltage everyone seems to seek.

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.

I'm not trying to just pick on @Sojourner1 and @toms, but what they are saying doesn't make sense. "It is chemically impossible to simulate". What? Simulations are based on extrapolation of what we know. There is no "chemical" limitation to simulation.

If I'm to understand what these guys are saying, we can't predict anything until we have lived it.

Astrophysicists will be disappointed that we can't even attempt to project when the sun will explode, until it does.

The weatherman will have to admit he has no idea what the weather will be tomorrow. When it does snow, then he will know. Oh well.

I am certain that @toms and maybe @Sojourner1 (I have no idea) have something useful to contribute to this noble thread. Good on @Go2Guy for taking this on, as I'm not sure any of us would have tried. In hindsight, this seems like some sort of hazing: No one knows anything until they suffer through it, and then those who have learned the hard way don't look back and try to help those who are struggling up the mountain.

There is a load of good info here to find, but telling everyone to just "search" and learn the hard way seems unnecessary and cruel.

This is frustrating. Again, I applaud @Go2Guy for trying, and @curiouscarbon for having the consistent positive outlook. I'm out.

 

[Maintenance guy]

Quote;
"Astrophysicists will be disappointed that we can't even attempt to project when the sun will explode, until it does."

Funny how Ashole Physics don't know crap about the sun when all information is a complete lie. who said the sun will explode and what false parameter are the basing it on. the Sun is NOT a Nuclear Fusion star, it is an energy converter creating Hydrogen plasma on demand in such abundance yet being burned off immediately. Hydrogen is one of the most electrically active and abundant elements in our universe. when ever there is electric fields there are magnetic field which can be accounted for in this scenario.
the surface of the sun has crated the perfect conditions for creating Hydrogen on demand in an ungodly amount. if it was Fusion it would of died a long time ago. the reason it is still here is it is a HYDROGEN based energy converter from counter space into space. thus accounting for both electric and magnetic fields.

another thing is why do you think the surface is 10 million degrees and the core is 6000.? remember heat radiates from the source so DUH! the heat is radiating from the outside in NOT the other way around. people are so easily fooled it is not funny.

anyways have a good day thus end todays lesson of SUN 101 and how NOT to listen to ashole physics.

 

[robby]

Go2Guy if you haven't realized it by now you need to pick a voltage that works for you. Many responses and post are parroting responses from others with little longterm use.

The answer you seek will only come in time. Tom's can give you #s that has worked for him for over 10 years. I can give #s that have worked for 6 years. Another will give #s that worked for X amount of years. Only time will give the exact voltage everyone seems to seek. ??

The problem is that by time we get the definitive answers the questions will no longer be relevant.

 

[toms]

"It is chemically impossible to simulate". What? Simulations are based on extrapolation of what we know. There is no "chemical" limitation to simulation.

The reaction in a LiFePO4 cell changes as the C rate changes. If you test at 1C, the results are invalid for 0.5C.

edit: apologies for not going into greater detail - not much time at the moment. It concerns me that there is so much misinformation around especially on this forum regarding LiFePO4.

It’s a shame many of the forums where the exact same discussions were taking place a decade ago are no longer active (and all the people who thought they knew best are now onto their second or third set of cells and unwilling to share their failures online)

 

[Go2Guy]

Go2Guy if you haven't realized it by now you need to pick a voltage that works for you. Many responses and post are parroting responses from others with little longterm use.

The answer you seek will only come in time. Tom's can give you #s that has worked for him for over 10 years. I can give #s that have worked for 6 years. Another will give #s that worked for X amount of years. Only time will give the exact voltage everyone seems to seek. ??

i agree, BUT again i had nothing to go off beside scattered tidbits of info from every where that was not digestable, where does one even start. . my goal when starting was to find the ideal settings, as you likely noticed the paramters i posted were not static but dynamic, ever number on the list a high point and low point of what would be ideal for your use case while keeping maximum longevity and minimum cell stress in mind. . . as far as im aware this data did not exist any where on the whole web IN A SINGLE PLACE instead tidbits here and there, my goal was compliation for both my self and others, and seems i have achieved, that, not sure if you checked my first post since [it has been edited as a answer post for others who may be looking for such numbers] but it is a open flexibile write up that gives understanding and choices when shooting for maximum longevity

 

[Go2Guy]

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

It concerns me that there is so much misinformation around especially on this forum regarding LiFePO4.

tom please do clarify what exactly is wrong, im wish to correct any errors to the main post, i want to take all data into consideration for that write up in the first post, again my goal is a single place where others can go the have all the details how to program there controllers IF maxium longevity and minium cell stress is there goal, If that is not there goal there is plenty of of other resources, BUT on this exact goal very little. ,I am aware each system is different hence the write in the first post up accounts for that by explaining and being flexible with the voltages you choose all while keeping maxium longevity in mind

 

[curiouscarbon]

The reaction in a LiFePO4 cell changes as the C rate changes. If you test at 1C, the results are invalid for 0.5C.

@toms

Agree! C-rate Dependence Of Degradation is Real!

With all due respect, I believe that C rate changing results does not imply that simulation is impossible. This is a matter of logging and analysis.

If you have run a pack for 10, 20 years with no logging, I recognize you may have experience, but no data.

With all due respect, data is worth more than experience to me! I respect your experience, but I did Not Have It!

C-rate is just another parameter to measure and log and analyze.

edit: trying to keep this on topic. ya'll are too hungry to beat up on people nursing their packs or trying to extend operational runtime. back off of people lacking money, you jerks.