technology seems fine. sales techniques and shipping are questionable.
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It is also amazing that you reply to me so fast!
Please don't presume to know what I will complain about.
That doesn't precisely match what I have observed, Davide, but I won't claim to have exhaustive knowledge or to have made a statistically significant number of observations here, either.
That is to say, I have drained an old style TS 200Ah cell to 0V at a rate of 0.1C and left it there overnight and though it did swell slightly, it was not to near the extent of ones that got that way when in EV service. I suspect that the truth may prove to be that going below 10% SoC while pulling high amps is the real cause of swelling.
However, if swelling only occurs when SoC gets critically low then I agree that a stronger case is not necessary.
I apologize. I must have misread when you said "... one thing that definitely needs improvement is the rigidity of the cell casings. ... This, to me, is totally unacceptable ..."
Did you do it on purpose or was it an accident? Bringing a TS cell below 2 V damages it severely.
I am not aware of a mechanism that would result in swelling of a cell that was brought down to 0 V (cells are never brought below 2.0 V).I guess that whether or not a cell swells at 0 V is moot, given that it is already severely damaged.
Swelling occurs at full SOC (100 % = 4.0 V), not at empty (0% = 2.5 V).
And, a user provided way of preventing expansion is indeed necessary if you're going to charge them fully. And Thundersky insists that you must do so: partial charges are not acceptable.
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ENTOURAGE FORUM
Oh no, you read that right. I was saying to not presume what I might complain about next...
Sort of both... I was testing cells for capacity, internal resistance and temperature sensitivity to help the Soliton1 deal with their peculiarities better. This particular cell - that I picked at random from a batch Rebirth Auto ordered for a conversion (they wisely bought 5 extra cells) - had about 190Ah of capacity whereas the others had closer to 210. I expected it to take more than 10 hours to fully discharge but it only took less (I guess about 9.75). As you probably know, discharging a cell for just 1 minute too long is more than enough to kick it's voltage into the dirt...
Did you do it on purpose or was it an accident? Bringing a TS cell below 2 V damages it severely.
The cell did charge back up just fine at 40A and absorbed ~195Ah which it then delivered again without complaint. I have not gotten around to seeing whether the internal resistance has changed, and I cheerfully admit this is but one data point, but so far it seems that the rate at which you discharge a cell has some effect on the amount of damage done.
No offense - seriously - but I have not gotten the impression that anyone really knows what is going on inside a lithium-ion cell. There's more physical chemistry than electrochemistry at work here, it seems, (ie. - the black magic and voodoo zone of chemistry). I mean, the manufacturers themselves can't seem to agree on such basics as what the nominal voltage is, or what voltage to charge the cells to, etc...
So you are saying that overcharging - or, more specifically, charging to exactly full - is what causes swelling?
That is definitely not what Rebirth Auto has experienced. Cells are fine before going on an endurance test drive; cells are swollen with some at 0V, even, upon returning to the shop. This is with the Soliton1 controller set to limit current when the pack voltage dropped to an average of 3.0V per cell, btw (once again arguing for the importance of a cell-level BMS, but I suspect you understand that quite well
)i do not mean that BMS and cooling is the same thing,i was wondering what is the product on the web http://www.evnetics.com/.
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