Sattva Ram
100 W
- Joined
- Jan 4, 2020
- Messages
- 271
I'm seriously vacilating between the 40H and the 60H mid drives. The 40H is 3200 rpm 48v 4kg and the 60H is 3200 60v 5.4kg. The plan is either buy the small with a far driver 72300 (s12) spun at 7k rpm at 21s with around 170% flux weakening with a 10.2 to 1 reduction giving around 85 kph top speed with a 110 kg bike including me. Or buy the bigger one spinning at around 6k rpm with a 8.36 reduction with the same top speed with the far driver 72360. My main problem is not knowing where the saturation point of the small one might be maybe 300 phase is just too much for the small motor? I'm confident that 360 phase is within saturation point for the big one but who knows if the small is just too small. Sure the big one would be a safer bet and if they were not fanned it would be a no brainer to buy the big due to thermal problems. But since they are fanned and i'll hole it up like a swiss cheese the small might just suffice after all with a shaft driven fan the continuous rating with these knows no limit. I'm shooting for 100amps continuous for both thanks to the fan and i think both could do it. The main question is rather if the small woud get saturated at 300 initial phase current. Sure the bigger would have more punch and bigger overall efficiency but it's wider and needs large q factor also has bigger resistance due to bigger rotor. My line of thinking is that the 7.6kg qs 165 sur ron spm motor gets saturated at 500 phase this is a kinda well known data. so if i base it off of kilograms the 4 kg small motor has to have around 240ish saturation point it's not entirelly linear tho for a smaller motor always has worse rotor/winding mass per overall kg. However the sur ron is spm and this is ipm. Is it possible that the ipm saturates better and maybe be able to squezee out the coveted 300 phase from the small one? Or maybe it doesnt even matter because even 240 phase would make a normal small wheelbase bicycle wheelie so max phase couldnt be utilized anyway and when it's no longer wheelie happy having gained some angular momentum the phase amps taper below saturation anyway...(of course it highly depends on gearing also). It's my first mid build i know what's what in hub land but i'm a noob in the midfled.
Any expert advice is appreciated.
Any expert advice is appreciated.