I have 140 of the same 18650 cells. There's about five different groups ranging in different voltages: 3.63V, 3.73V, 3.83V, 3.92, and 4.04V.
This is my first battery build, will be 72V 20s7p. So far what I read is that I have to match the cells that will be in parallel, to within 0.001 volts of each other. How far can they be off from each other?
When it comes to joining them in series, does voltage matching matter?
3rd question: Should I just fully charge all of them before spot welding?
Thanks in advance endless sphere universe!
This is my first battery build, will be 72V 20s7p. So far what I read is that I have to match the cells that will be in parallel, to within 0.001 volts of each other. How far can they be off from each other?
When it comes to joining them in series, does voltage matching matter?
3rd question: Should I just fully charge all of them before spot welding?
Thanks in advance endless sphere universe!