The need to compress cells is about the plastic case cells. They can expand during normal charging. It is not an issue with the aluminum cased cells. They will only expand during over charging, and that you must never do. The ends of any cell do not need compression.
280ah Battery Top and Bottom Support Design.
- Thread starter Heap64
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Sojourner1
Itinerant
Is this your opinion or do you have documentation that one kind of cell case expands more than another while charging?
Granted mine are "compressed" and I would compress any prismatic cell and wouldn't worry about xx amount of pressure, just get them snug, something is better than nothing especially if your in it for the long haul of ownership/ use but it's my opinion and what I practice. Here is a close up shot of one of my packs, these prismatic cells with thicker bands in sections look to better than a thin wall aluminium cell. Again just my opinion.
Sojourner1
Itinerant
sremick
Mostly competent. Knows enough to be dangerous
This seems counter-intuitive to me as well. From what I can tell, the expensive cells (Winston/Thundersky, CALB, etc) build their cells with a hard plastic case to provide a degree of structural integrity and make compression easier. The cheaper cells (EVE, etc) skip this, resulting in smaller batteries and lower manufacturing costs, with the expectation that the integrator is now responsible 100% for proper containment.
It gives me the impression that the former are targeted more towards end users, while the latter more towards OEMs.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
IF IN DOUBT, DEFER TO MANUFACTURER DOCS & SPECS.
Having dealt with the odd Aluminium Cased cell, I bind them snuggly at about 15 PSI when at mid charge state. Such binding is suggested & supported by the manufacturers.
But here are TWO Tier-1 Top Brand Manuals, what they suggest.
Also the GOLD is in the explanations & understanding of LFP chemistry explained as well.
Thundersky LFP Cell Manual: (binding/fixing) they even include straps & plates. PILES of other excellent LFP info in there.
CALB Products User Manual:
Having dealt with the odd Aluminium Cased cell, I bind them snuggly at about 15 PSI when at mid charge state. Such binding is suggested & supported by the manufacturers.
But here are TWO Tier-1 Top Brand Manuals, what they suggest.
Also the GOLD is in the explanations & understanding of LFP chemistry explained as well.
Thundersky LFP Cell Manual: (binding/fixing) they even include straps & plates. PILES of other excellent LFP info in there.
CALB Products User Manual:
Sojourner1
Itinerant
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Just remember that every company has it's own specific chemistry tricks and so their docs reflect such. Always refer to Your Cells Manufacturers datasheets. These do provide excellent reference info on the chemistry, the settling and knee points etc
Sojourner1
Itinerant
For folks reading the Thundersky manual it's a 2007 version so some specific data may be dated now but certainly some good info in there.
And, just for reference, Frey aluminum cells, with their fancy plastic separator shells, specifically are not compressed during build. (And they also do not expand at 100% SOC.)
So either some manufacturers build in extra volume to accommodate it, or their chemistry minimizes it, or the shell itself exerts enough clamping pressure on the jelly roll to achieve an equivalent result without external force.
So either some manufacturers build in extra volume to accommodate it, or their chemistry minimizes it, or the shell itself exerts enough clamping pressure on the jelly roll to achieve an equivalent result without external force.
Yes it is my opinion. I have read every white paper I could find. Perused many web sites. Talked to many manufacturer representatives. So I have a well researched opinion. I'm happy to share with the understanding I will no longer provide lists of my references. I get hammered too often. But let it be known, I also learn much on this forum and do change my opinion if found new information. It is the best advice to check with the manufacture of the cells you have.
Sojourner1
Itinerant
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
We should not forget that wives tales that live forever even when known to be bogus. Then there are things that go across like issues specifically related to FLA batteries that get shifted on Lithium Cells. Also let us not forget that "all lithium catches fire & blows up" nonsense that continues to pervade since the early LiPoly cells had those faults.... and not nescessarily battery fault but stupid user fault too).
I saw a video (can't find it) of someone firing a 45 Cal Round through a pack of LFP going right through all the cells and no fire, no smoke, no dead. Just a huge mess and cells that need to go off for Recycling. Try that with a Tesla Pack and see what happens... hehehe
I saw a video (can't find it) of someone firing a 45 Cal Round through a pack of LFP going right through all the cells and no fire, no smoke, no dead. Just a huge mess and cells that need to go off for Recycling. Try that with a Tesla Pack and see what happens... hehehe
My experience is the exact opposite. I have 100 Ahr Calbs (28 of them) used in my RV for 6 years. They are plastic cased. I have them restrained since they are on the road but I never banded them to stop expansion. Not one of them has swollen in six years. On the other hand, you just need to spend 10 minutes on here or youtube discussing the eve and lishen cells and you can actually see them expand and contract when they are barnd new. That plastic coat on the calbs is really really rigid and tough.
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