Sparfuchs said:
I guess i quite understand how volts and amps and windings influence motors. But when it comes to battery building it seems like the only reason why people make less serial connections is to be able to get enough parallel cells for the wanted discharge.
The motor Kv/winding issue is completely separate from P vs S / V vs A at the battery level.
> But what if you have enough discharge anyway no matter if you use 16s or 21s. Can the higher voltage also be an disadvantage somehow ?
So first you determine your desired voltage from the motor POV - for efficiency, just a bit higher than what is needed to get your desired top speed.
That voltage changes if you are rewinding, but that's already been thoroughly discussed.
The point is yes, do not increase voltage unnecessarily, just what you need no more.
So, once you know your desired system / nominal voltage, that gives you your S-count, depending on chemistry but usually using li-ion 3.6-3.7V per.
16S if you wanted 60Vnominal
13S for 48V, 20S for 72V
Now you get into your need for current, peaks vs constant.
That determines your parallel cell count, depending on how many mAh / Ah per cell.
A 3Ah cell requires a lot more connections vs a 20Ah cell.
Range is a big factor, if you want a 50mile run per charge you have a bigger / heavier pack much higher Ah capacity
so lower C-rate discharge, do not need high-power cells, can choose those designed for energy density instead.
But low size and weight targets, "fun" level performance conversely reduces max Ah and range, might need to prioritize power density instead.
Does that help clarify?