Howdy; I am currently in the process of testing (360) 18650 cells using the LiitoKala Lii-500, which can do (4) cells at a time--and I have two units. I also have another "dumb"charger only that does (4) cells at 1A per cell.
My capacity tests are taking 6-8 hrs each at 1A ea--and that is using cells that have been charged to 4.2V first using my "dumb" chargerso that the cells don't have to first be charged up to 4.2V by the Lii-500 units...plus, I am also pulling the cells out after the END of the capacity test while the cells are being charged, which means that my tested cells have Ah capacities and mR resistance figures--but they have not been charged back up to 4.2V, which means that the tested cells are in various voltage states (2.9-4.2V).
I am building (3) 7s16p banks into a 7s48p battery using Jehu's PCBs (plus a BMS per bank). I plan on using rePackr to determine where to put the cells to createbalanced 7s16p banks.
My question is how big of a deal is it that the tested cells be populated in the PCBs be voltage matched? For instance, is it a big deal if I load (7) cells onto a given board--and then add that 7s cell into a larger 16p bank--with all of the individual 18650 cells in various states of voltage levels?
The reason I ask is that to charge the tested cells back up to 4.2V so that all cells have a similar voltage level is taking 2-4 hrs using my "dumb" charger...and given that I have so many 18650 cells to test, re-charging all the cells back to 4.2V is adding quite a bit of charging time. So I'm just trying to figure out if I can let my BMS handle the voltage balancing once my 18650 cells are populated into my 7s16p banks. From what understand, the BMS should balance all of the cells within the 7s16p bank. Is there a reason that I can just let the BMS equalize all of the voltages during the first charge of the 7s16p banks?
Thanks for your help--I REALLY appreciate it.
My capacity tests are taking 6-8 hrs each at 1A ea--and that is using cells that have been charged to 4.2V first using my "dumb" chargerso that the cells don't have to first be charged up to 4.2V by the Lii-500 units...plus, I am also pulling the cells out after the END of the capacity test while the cells are being charged, which means that my tested cells have Ah capacities and mR resistance figures--but they have not been charged back up to 4.2V, which means that the tested cells are in various voltage states (2.9-4.2V).
I am building (3) 7s16p banks into a 7s48p battery using Jehu's PCBs (plus a BMS per bank). I plan on using rePackr to determine where to put the cells to createbalanced 7s16p banks.
My question is how big of a deal is it that the tested cells be populated in the PCBs be voltage matched? For instance, is it a big deal if I load (7) cells onto a given board--and then add that 7s cell into a larger 16p bank--with all of the individual 18650 cells in various states of voltage levels?
The reason I ask is that to charge the tested cells back up to 4.2V so that all cells have a similar voltage level is taking 2-4 hrs using my "dumb" charger...and given that I have so many 18650 cells to test, re-charging all the cells back to 4.2V is adding quite a bit of charging time. So I'm just trying to figure out if I can let my BMS handle the voltage balancing once my 18650 cells are populated into my 7s16p banks. From what understand, the BMS should balance all of the cells within the 7s16p bank. Is there a reason that I can just let the BMS equalize all of the voltages during the first charge of the 7s16p banks?
Thanks for your help--I REALLY appreciate it.