Each cells was exactly 213 ah? Do they all discharge and charge to the same value? Have you pulled the whole pack down below 3.0 volts per cell?
This is Kevin from Hipower, very glad to meet you. I would give some suggestion about your question. Batteries would made some extra AH, for high C-rate discharge.. Our engineers would make about 5% to extend 3C continuous discharge, they think it is enough.
Hipower battery is somehow different than Thundersky or CLAB, We use "Aqueous solution" technology, it is more suitable for electron translation in Aqueous liquid, the charge and discharge ability is better than "oily solution", and it is more safe. The "Aqueous solution" is translated as Chinese mean, I don't know the real English word is. However, this improved technology really have better discharge curve, and it is easier to control cell's quality as electrical property of cells in producing, cell would have more "same" property as IR, charge / discharge characteristic.
For battery packs, Hipower select the most same cells to assemble battery pack. We use CLMT (cycling,logging, matching,testing) quality control method. Use machine to pick up cells which have most same IR, as candidate, then do charge / discharge cycles, find out the most same charge / discharge curves, them pick up those cells, to make up battery pack. Our acceptable quality level is : With standard discharge to 80%DOD, the difference of cell's voltage in pack should less than 0.1V. charge to 80%SOC, the difference of cell's voltage in pack should less in 0.1V also.
If you take Hipower batteries, we could offer technical detail support, like fast charging restrict, temperature upping with different C-rate, best discharging condition consider the cycle life. We think no one know our battery than our-selfs, we need to be honest, tell customer what can do or what can not do. Customer is not a battery professor but sales need to be. So the relation is health.
Some useful information:
For all Li-batteries, the best using condition is not totally charged or totally discharged, it due to Li-battery chemistry.
So, in 100%DOD can cycle 1000 times, while in 80%DOD can use 2000 times. charge to 3.65V is better than 3.85V to extend the life cycles.
All li-batteries, there is liquid in cell, if temperature is too cold, the electron in liquid would not be easily transported. The capacity would be "frozen", some of capacity can not be fully discharged. when temperature returns to normal, the rest capacity (energy) can be discharged. So design a battery box with heat insulating marital to stop cold temperature effect the battery in winter is better. You may also design some of heating wires to warm cells. For Hipower batteries, when discharging, the temperature would rise about 5 Celsius degree with 0.5C continuous discharge, 10 Celsius degree with 1C continuous discharge.
For fast charging, All Li-battery charging method is CC/CV, and they need balancing time. Hipower battery can take 1C current charing is CC mode, which is 0%~90% SOC, 1C continuous is no effect to cycle life. While for CV mode, which is balancing time, need about 1~2 hours.
I hope it would be helpful.