kgf is just kg, but clarifying that it is force not mass. On Earth with 1g gravity, kgf=kgm=kg=2.2lbs. So 300kgf is 660lbs, not what I would call light pressure.
I’m trying to get clarification from EVE on the “fixture” and how the 300kgf force is applied.
There may have been more details in the full document. I can't speculate exactly on pack configuration.
No, units are kgf not kgf/cm2. Yes if you applied 300kg (660lbs) to a 100cm2 plate then the pressure would be 3kgf/cm2 (6.6lb/cm2).It would have to be kgf/sqcm
660kg over 100cm2 is only 6.6kg
But again, 2500 cycles is already pretty high, not sure that’s worth the trouble.
whats odd is i have older version of the specification may 25 2018 and unter 5 cycle life it say 3500 cycle with no break down for fixture.
I just went over my document comparing to the one you posted and it word for word except 2 things. the mention of fixture and the graph showing that info. The other item mine list the discharge current at 1c and your is .5cInteresting, I wonder if this is due to a difference in cells, a difference in measurement, a different assumption on fixture or another factor, or just sloppiness/inaccuracy/unreliability
now it makes since. I wonder if this is current or there has been other updates . I will print this one . I got my from the seller of the cells i hope the cells are not as old as the specifications.
When reviewing the specification updates - significant items change in Revision D and E. Sometime these documents are difficult to read -as related information is not clearly identified without the reader making some correlative assumptions between document sections.
Even in a stationary application my building inspector will surely require some form of seismic constraint. So i can accomplish both objectives if I give it some thought during assembly.Regardless, some fixture is required to prevent cell post damage in "non-stationary" applications.
yes the official with jurisdiction is worth considering. Got to pick and choose which details are worth discussion. Combustible construction might be an issue.I
Even in a stationary application my building inspector will surely require some form of seismic constraint. So i can accomplish both objectives if I give it some thought during assembly.
Agreed it is about preventing bulging with charging. I'm not clear if the longevity issue is related to the cells themselves or to repeated flexing of the terminals due to the bulging. My plan is to use 1/4" 6061-T6 aluminum plate with threaded rod and a Lucite top, similar to what many have done including mainesail at marinehowto.com. Tighten lightly at low SOC, then expansion with charging will create its own pressure due to the rigid structure. Of course that is a variable and unknown amount of pressure, but it seems like a tried and proven solution.Yeah need confirmation, and also the correct way to do it. I hadn't thought of springs before reading your guys posts, I assumed more like really long bolts or wire set to a fixed length.
I suspect the reason is to keep it from bulging, so it might be reasonable to fit them together at low charge and only have real pressure at high charge to prevent any movement.
Not sure who you're talking to here but it seems like a nice civil discussion to me. If you have any manufacturer information from EVE on recommendations for compression could you post it?Bottom Line: Follow the Manufacturers Specs & Documents and everything else is on you. Some people always seem to think they know more than the Scientists or Engineers who designed the material/equipment, they can take whatever risks they choose because it is their money & lives they are risking. Smart Money is on those who follow the guidelines and Best Practices (who some will argue against) for the longest lived, better functioning system while squeezing the maximum out of the investment dollars.
It's funny how dividing such a simple thing can be, because of opinions.
Also funny is that many opinions originate from people who have never RTFM'd anything who always wind up with extra pieces from a kit they assembled.
Completely agreeRegarding whether its worth the trouble, I don't think designing for compression would be any more trouble than designing for airflow/spacing (though designing for precisely 300kgf might be difficult/overkill)
Would be nice to get some clarity from EVE, as well as some clarity on whether this is a factor with other cell manufacturers or cell sizes.