Yes, i have. You’ll notice the author of that post no longer frequents this forum.
Don't be so sure about that... ?
The funny thing is that nobody would recommend connecting cells of significantly different states of charge in parallel,
What if it's done, and current is within rated spec? I've done it. You even liked that
post. ?
Off grid garage demonstrated that 0% and 100% SoC 280ah cells
will not push > 0.5C for very long. How much will there by with a simple 0.05V difference in cells that are
only 12% apart?
and nobody would recommend holding a LiFePO4 cell at a fully charged voltage.
Except for Battleborn when instructing a customer to hold a battery at 14.6V for 20-30 minutes per string in parallel with no qualification on current. Few charge at 0.5C, so lower current charges require less absorption. I'm pretty confident that these scenarios often result in charges tapering to < 0.05C. Additionally, horribly imbalanced BB with a little over 50% capacity can be restored to > 90% capacity by
holding at 14.2V+ for a week. I can't imagine that one or more cells weren't held at true 100% for that entire duration. Sure, plating may have occurred, but is it really that much of a problem? Unfortunately, we don't know the end result as that user hasn't returned.
Weren't the first iteration of these cells originally ran from 4.2 to 2.0V to extract that extra few %? Does holding a cell at 3.65V really do that much harm by comparison?
Yet plenty of people think it’s a good idea to combine those two bad ideas.
Lots of options between always and never and understanding the risks, limitations and benefits.
I have experience with NMC cells showing across the board improvement with balance charges to 4.20V down to .002C. Repeated charges saw IR cut to 1/3 the initial value and 2-3% total capacity gains. Sure. Maybe I'm doing something that harms the cells, but they're better than they were, and they will never be charged this aggressively again in service.
Top balancing may not be a best practice, but in this world of gray market cells, it's mandatory in many cases. My 9 EVE cells were received at between 28 and 40% SoC (yes, I discharged as-received to 2.5V to measure). That's a substantial deviation that would have been tedious to deal with, though, to your point, some of the active balancers would have made it bearable. A JK would have taken at least 22 hours of continuous 2A balancing assuming perfect transfer efficiency, and many cells would have had to be maintained at 3.65V to make that happen.
It's worth mentioning that the top balancing guide instructs one to charge in series to BMS cut-off discharge. If one can extract rated capacity from the battery, no top balance is necessary.
