How important is the cut-off current when top balancing or capacity testing cells?

[SimpleJack]

Hello, I am a newbie trying to figure out the best way to charge (for capacity tests) and top balance my cells.

I have 2 packs of 8 280Ah Eve cells and a LeTkingok EBC-A40L for charging and testing.

Would it be a problem if I were to charge a single cell for a capacity test to 3.65 volts, not use the 0.05C cut-off current of 14amps, and stop charging right when the volts hit 3.65? I cant imagine I would leave much power left to be filled. Or is it bad for the cells not to slowly ramp down charging down to the 0.05C?

Additionally, if I were to top balance 8x280Ah cells in parallel, the 0.05C rating for those cells is well above the 40amps I am putting into the pack. Could I just top balance the pack to 3.65 and have the charger stop upon hitting that 3.65 value?

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[Sean Very North]

Do some reading around the topic of tail current, you absolutely no not want to be ceasing charge based on either a voltage or a period of time.

 

[SimpleJack]

Thanks for the reply. I found this in the Beginners Resources:

...

1.The most advanced (best) chargers will have a current setting that the charge must get down to before going to float mode.
(These chargers will often also have a max time the battery is allowed to stay in accumulation stage.)
I tend to set the cut off current for the end of the accumulation stage quite low. Typically .5%C to 1%C. (EXAMPLE: .5%C on a
200AH battery would be .005 x 200 = 1A) Others are less aggressive and set it to as high as 5C (Example .05 x 200 = 10A)

2. Less advanced chargers will only have a timer on the accumulation stage. I will typically set this to .5 1 hour.

3.The least advanced chargers will switch to float mode as soon as the target voltage is reached.

All 3 algorithms work, and, in my opinion none of them are ‘bad’. However, each gives slightly different level of control of the State of Charge when the charging completes.
...

Would what I suggested be the same as point #3? I don't plan on regularly charging the cells this way, just for top-balancing.