Offroader said:I'd like to see this thread about charging but I believe it is understood that higher charging rates, even if below the battery spec, seems to do a lot of damage.
This is why I usually charge my cells at around .2C charge. I don't care most of the time if it takes 2 hours of 8 hours to charge my pack.
My 18650GA samsung cells are rated at a 1.6 amp charge rate per cell (about .5 C charge), but since I have 14 of them in parallel, I don't care about charging them at .7 amps each cells. Still gives me a 700 watt charge rate because my pack is so large. It also still heats the pack up by a decent amount at that low charge rate.
But if one was to use these 18650 GA 3500 cells and charge them at 1.5 amp per cell, I agree you would get diminished life from the. I only know of one person who charged them above spec at like 3 amps per cell, and he got greatly diminished capacity.
Discharge at higher rates is probably not that much better, but most of us pulse the discharge when riding. If one was to run it full rated discharge, even half the rated discharge, you would probably get reduced capacity quickly, and a very hot battery.
There was some discussion and tests done in this thread on various cells: https://endless-sphere.com/forums/viewtopic.php?f=14&t=68556&start=100
Both at high 1C charge currents where cycle life was garbage, and also 1C with 85% DOD.
Also we know Tesla super chargers are charging at around 1.5C+. They are using cells similar to the NCR18650BE/BD. The cells they are not using are not magical or anything. But guess what, go ahead and try to some cycles on some Tesla cells or even similar Panasonic cells at 1 to 1.5C with a 4.20v CC/CV charger. I guarantee you, you will see massive massive capacity losses after 100 cycles. Yet there have been Tesla's with 150-200K miles on them where they were only charged using super chargers and they still have decent capacity left. I think the trick is in the charge voltages at or around 4v and higher. I believe Tesla doesn't use CC/CV but uses something like what I described in my last post, they start reducing the current much quicker than a normal CC/CV charge method. And I'm sure a little chilled liquid cooling on the battery pack helps also.