Why you should compress your LiFePO4 battery! And why it does not matter... 🤷‍♂️ - ndbatteries.com

Why you should compress your LiFePO4 battery! And why it does not matter… 🤷‍♂️

Off-Grid Garage
Views: 24312
Like: 1817
I know, I know… the oldest question since the invention of lithium batteries again: should you compress or should you not compress your cells?
To answer this question, I have here some information form a battery expert which I explain very detailed in this video. Mainly there is only one reason to compress your cells. And this only for a certain amount of time.
Well, who would have thought that the actual reason so many people compress, has nothing to do with extending the life of the batteries.
All information here in this video…

Dominik’s YouTube Channel, @Zerobrain: LiFePO4 – ALLES und noch viel mehr über Lithium Akkus:

Why compression will not extend battery life (something else kills your battery):

EVE R&D Test Procedures:

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  1. Reason2 for compress; prevent stress on busbars when overtime swelling may happen

  2. Andy, as always, a fascinating video. Thanks! Still. I think you may be taking Marcus' explanation too far. WAY TOO far. He is absolutely correct about the atomic swelling caused during charging. Absolutely that happens and can't be prevented. But that particular swelling is not the swelling you're seeing on your batteries. The swelling your batteries are experiencing is simple mechanical swelling caused by incompletely constrained prismatic cell structures that are exposed to cyclic (smaller) swelling caused by the charge and discharge cycles. Unconstrained it slowly results in a permanent bulge focused in the center of the bottom quarter of a prismatic structure under relentless gravitational pull. Look at a year old acrylic aquarium, they all have exactly that same bulge in the same location.

    If that's not the bulge on your batteries then explain why it took a year for your batteries to bulge to the point that arrested your attention to them. If it had been only the atomic charge bulge they would've expanded to what they are now on the first charge or two. They did not.

    The battery makers build the cases out of the thinnest material that can mechanically support the expected handling forces. They could, but they don't, make them thick enough to hold their form without external assistance. It allows a battery pack to be smaller and much lighter to have the additional force externally applied. And, of course, it saves them lots of $$.

    Look at any commercial LiFePO4 batteries. Not these shlocked together ones in our home energy market I mean ones made by the thousands for industrial applications by actual battery companies for public transport or stationary utility storage. They'll be compressed.

  3. flexible Busbar, wären empfehlenswert, hmm besten dicke Litzen 35-50mm2 mit Rohrkabelschuhen je nach Stromstärke

  4. Great information Andy! Love it and thank you for sharing!!! I have not heard some of that! You are 100% correct how some of those places test there 1000 cells at a time. I was sent a similar video and pictures when I purchased mine lol. I would like to add one benefit of compressing or fixing a group of cells. The accidental or unintentional overcharging of a cell or cells from a faulty bms or whatever the reason. You can prevent the pack from making a smiley face😀which may help from damaging other cells and depending on the area the cells are in could prevent damage to other equipment. Dont mind me, I over think EVERYTHING!! 🙄

  5. Yes, it doesn't matter, if there is a low cycle rate like you have, with about 50 a year. Such a off-grid system will die mostly because of calendar aging, especially when charging high, keeping high SOC, and at high temperatures.

    But some are using their batteries much more intense with lower capacity, just for daily solar storage and have 150 – 200 full cycles a year. And this may go even higher by additionally optimizing usage of a variable grid tariff, having even more cycles per year.

    BTW, not one of the numerous scientific research papers regarding lithium cell compression I read, mentions any bubbles in the electrodes as reason for doing compression, but talks about reversible and irreversible expansion. The irreversible expansion (mostly SEI growth) is reduced by the constant pressure. Some papers even talk about using the increasing irreversible expansion during aging as indicator for SOH. So it is not so that expansion stops after some number of cycles. The expansion increase the all time, especially if you charge above 3,40 V/cell.

    Compression doesn't cost much extra, for the chance of considerable improvement of long-term capacity and internal resistance, in grid setups with more cycling. So why not?

  6. Another hugely useful piece of information. Guess I skip buying compression gear from Bunnings now : )

  7. Nicht richtig was sie sagen. Schau mahl auf minute 2 von Dominik video. Gasbildung und wo gas ist..ist KEINE elektrische transport !!

  8. Is there actually any data on aging of lfp batteries without cycling them?

  9. That's so interesting.
    So on your reasoning, organizing the cells in a configuration where they lay on their side, as was shown on your video on the clip of the reseller, would also be harmful?

  10. 😂❤ "…..der Drops ist gelutscht" 🎉👍👍👍

  11. 😂I dont, but I still love you too.

  12. Congratulations for the video…great information and great show 😉

  13. There is a YouTube video showing a guy overcharge lifep04 cells 280ah cells. almost as thick as wide after the bulge from over charging with a higher voltage. didnt blow the relief valve(vent plug) or whatever that is. they still work. I think under compression it would have blown the vent hole plug and then you would see fire coming from them like you do with these china BYD cars are doing, go watch these BYD cars on fire it shows when it starts and looks like a flame thrower which means battery cells exploded through vent hole plug.

  14. I love the videos. You really make it fun. If you're not making money on this there's something wrong hahaha. You are so good. I wish I didn't run out of money. So I could mess around with some more solar stuff. It would be fun I would actually like to be able to do some small-time installs for people. As some sort of a side business. I'm a concrete delivery specialist but all of a sudden the economy went bad and I don't have much work. And I just bought a brand new truck $200,000. And now there's no work it went from crazy busy. Me complaining about too much work. And not getting any time to do anything. To barely getting any work. In about a three-month period of time. I'm sure glad I bought the off-grid solar systems that I have before I went broke haha. man I really like your videos

  15. I have compressed my 15 x 280ah EVE Batch Matched cells since I bought them, the where perfectly square.

    Had to take them apart and saw they have expanded indeed after a year.

    Why did I take them apart? Added 3 more for a 18 cells bank (3.45v x 18 = 62.1v) … I can because I use Victron equipment. 🙂
    Max volts on a 48v system is 66v.

  16. Keep it up brother! Very informative video! ❤

  17. It seems to me that if bubbles are an issue batteries should verbosely labeled “This Side Up”

  18. I'm going to agree to disagree on this one. I wish I wasn't under NDA for some of these aspects, but I've seen the difference first hand in my lab which included X-Ray/Neutron imaging of the cells to determine intercalation, morphology changes and degradation processes. Look up "4D imaging of lithium-batteries using correlative neutron and X-ray tomography with a virtual unrolling technique" and search 'compression' in that article. That was a study from 2020 in Nature.

  19. Hello ! I have started to build my own 12v battery after I have seen all your videos from the beginning until now. It is a small project but I am learning. Congratulations for all your good work and good advices! You are the best !

  20. Der Drops ist gerutscht.😂😂😂😂 Ich liebe Deine Videos.

  21. Thanks for sharing Andy, now I have another channel to watch as well 🤔, you made good points. I think I like your option of spacing between cells as your busbars won't get tense by the expansion of cells. Keep the sunny side up down under!

  22. Great breakdown on this issue where nobody could really give a clear answer. Happy to see it put to rest.

  23. Speicher System Victron Lifepo4 Batterie 5885ronny says:

    Danke fürs Video 👍👌

  24. That's been really interesting. Thanks for sharing. Any we have to understand, that when that another of cycles the batteries are still at 80%. No reason to throw them away if you ask me.

    And I love you too, Andy😘

  25. Great one Andy, answers a LOT of questions. We’re all still learning about these cells, and probably will still be in 30 years, (though based on family history I won’t be here then.)
    However in the meantime, I’m still planning to be here anyway. Maybe I can beat the odds, and maybe my batteries will also still be going. 😁

  26. Do you have a link for EVE batteries to buy them directly from the supplier? Thanks!

  27. Love your content Andy, there are some questions I would like to ask personally if I could get i touch with you directly regarding my Lithium battery! Would love your feedback.

  28. Why old cells like Sinopoly or WInston can be positioned at any position, not only with terminals up, and there is no compresion and cells do not swell after 10 – 15 years of using at 15 – 22 *C ? Thera are not layers on LiC6, there is current colector + binder + powder bind together. Layers of LiC6 are only at pictures to better present intercalation proecess.

  29. I have a research paper somewhere that is about 6month old that says compression is bad. They found out for absolute certain when they made semi transparent batteries to actually see if this is beneficial. Its not, compression makes it worse.

  30. Thank you for the great in depth knowledge about batteries!

  31. so in summary I understand it, if you want the cells to last thousands of cycles (if cycled daily) then compression makes sense. I.E a home battery that will almost daily cycle ? but only if they are tested only one time at manufacture (very unlikely)

  32. With compression there is no space left between the cells. Therefore you're save to get no ants (or other insects) in between the cells. This is a big advantage in a shed like you have 😁

  33. I just checked my Victron Connect BMV-700 [Google -> Upgrade ostrovní elektrárny 12-36kW, LiFePo4]. It let me know, that for the last 16 months (Jan-2022 I installed BMV-700) I did 13 total charge cycles. So in my case, for 2500 cycles I have to charge/discharge my cells for 256 years. Well I am fine with these numbers.😀. Thank you Andy, you are great!

  34. You forgot one thing:
    Compression is often important in moving environments (EV or RV) to protect the terminals of getting machanical tensions and pressure which can cause addidional damage to the cells.

    Grüße aus Deutschland!

  35. Hey Andy, great you used that fantastic Interview video. What is missing now is the aspect of connecting the cells. Bus bars are rigid whereas cables connect the cells in a flexible way and can compensate the breathing of the cells …

  36. Andy thank you for this video!
    It has really helped.
    I was getting so much contradicting information and was just confusing.

    This is a really solid explanation

  37. If you let them free you better use flexible bus bars

  38. Super, Dankeschön für die Aufklärung.
    Hab eine Powerwall aus China und die ist bestimmt auch nicht verprasst.

  39. Andy, if you were using the cells for vehicle propulsion, discharging over say 4 hrs then charging 4 hrs, again and again, then the number of cycles would be vital wouldn't it? Hence compression from day 1 seems to be best. But… as you ask, it only needs to be for a "few" cycles. Thank you for your great vids!

  40. One obvious benefit from compression is that you fix the whole assembly to avoid stress on the busbars,and you are right,for this you don't need much force, the assembled batteries in a PE casing does the job

  41. Hi Andy, i wrote a whole story on possible negative effects of not compressing (i've been studying lifepo4 chemistry since 2014)… but.. i deleted it. *because it does not matter*. The only thing that matters is keeping cell temperature as close as possibe to 25C (and above 10C). Things exponentially get worse at higher temperatures. When you keep your pack at 25C it will last 40+ years. If you abuse it, it will last 'only' 10+ years and loses 30% capacity… so what

  42. Your 75 cycles a year would indicate you over-dimensioned the system ;-). Or at least don't make good use of them. In the system I am planning, storing the summer solar energy and using it when there is no sun (covering 4-5 months a year of the energy needs of our house), but then in the other month I would use the dynamic tarrifs to charge for 4-5 hours on a lower tariff and then discharging the rest of the day… I could reach 200 Cycles a year depending on sizing of the batteries… Then the number of cycles becomes important…

  43. When I was building my 14kWh battery pack last year, I was told, that the compression isn't necessary for stationary application as a solar energy storage. I also knew, that the batteries do expand a bit, so I placed small spacers on the corners of batteries, where they don't expand, so they have some space and they won't apply stress to the bus bars. After watching Andy's former video abot this issue, I almost had a heart attack. I saw my euros going to Heaven. After checking I noticed, that the batteries expanded a bit after six months of operation and compression was put on my "to-do" list. But after watching this video I feel a bit more relaxed. I guess now they did what they meant by now so I will just loosen the bolts, relief the stress and tighten back. So, if you are about to build a new battery pack, at least put some spacers as I did, just a bit thicker, maybe 3 to 4 milimeter.

  44. Andy, thanks a lot ❤
    I will not compress my cells 🎉

  45. Has anybody tried batteries in a air tight case with 100 or so psi applied on them? (7 or so bars)

  46. I have some 24v 200ah AliExpress batteries that have pouch cells that are vacuum packed but as they face upwards into the void have no cell compression.

    Ecoworthy packs have bare pouch cells just loosely fitted in the box with a couple or bits of tape lol. I wonder how they will fare

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