Thinking some more about what pronghorn wrote (among others), and wondering:
thepronghorn wrote: ↑20 Oct 2020, 22:46
I'm not saying the per cell charge current decreases, just saying the total pack charge current decreases. 4P at 10A is 2.5A/cell, so a 2P pack would only be able to do 5A total.
to which
donn followed up:
Sure - but 5A at 72V, vs 10A at 36V, isn't it? = 360W. The actual voltage from the hub is something else, transformed by the controller to the battery voltage. If the controller is going to limit the battery side amperage to 5A@72V or 10A@36V, that should be at least roughly the same motor amps in either case, if the transform is done so that watts in = watts out.
My question: assuming the same capacity in the two battery packs (36V vs. 72V), why would the 72V pack take only 5A maximum charge current? Max. charge current for most packs appears to be related to capacity, i.e. =1C. (i.e. a 10Ah pack can take 10A max. charge current).
Wheel motor produced
power is what makes braking torque. I want to maximize braking torque. With the current limited to a common value (e.g. 10A), it would seem that higher voltage would allow for more power.
Observed: comparing two battery packs,
assuming the same voltage, higher parallelism (higher P number) means more capacity. More capacity means higher regen. current tolerance, which means more regen.
power at that voltage, therefore better braking. But this higher capacity means more cells, and that means more cost.
Proposed: comparing two battery packs
with the same capacity, a higher voltage pack (i.e. lower parallelism) can tolerate a higher regen.
power, because at higher voltage, the same maximum current would mean more power.
I'm still hanging on to this idea of higher voltage pack giving better regen. braking performance, all other things being equal.
Somebody break my logic!
Maybe I'm wrong about the same capacity packs allowing for the same max. charge current, even with the higher voltage packs?