I would like to launch this topic for discussion: Motor for the Propulsion Unit.
I have been analysing most of the builds posted in this forum and it seem that everyone it’s been using pretty much the same motor: SSS 56104/500KV Brushless Motor (https://www.ebay.com/itm/SSS-56104-500KV-Brushless-Motor-6-Poles-W-O-Water-Cooling-For-RC-Marine-Boats/282598123208?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649). From this link it can been seen that This motor can have a output of 11000W.
I have also seen that most of the builds have a battery pack with a 12s14p configuration. This configuration will work at approximately 48V and if we admit that the current will be around 90A ( Very high current!!! Most of the batteries can’t work at this current) the maximum electrical power that is delivered to the motor is 48 * 90 = 4320W. Basically, we will use less than half of the motor capacity. This over-dimensioning of the motor really freaks me out and there’s another issue with SSS 56104/500KV Brushless Motor : at 48V the motor will run at 500*48= 24000 rpm (witch is freaking HIGH!!!) and this introduces the need of implementing a gearbox (most of the guys use 5:1 planetary gearbox). I have to admit that these set-up seems very inefficient and can lead to a lower lifetime of the propulsion Unit
I gave some thoughts on this issue and to avoid the implementation of the Gearbox and the over-dimensioning of the motor i think that it would make much more sense to chose a motor with a Lower KV value and a lower power (since we are not using 11000W anyway). I was able to find a supplier of Inrunner brushless motors : Alien Power System and in this supplier i was able to identify two motor that could be used for this Hydrofoil apllication:
Admitting that we are using a battery pack with a 12s14p configuration i feel that these two motors are more indicated for this application.
Now i would like to hear everyone’s opinion on this.
Hereby some discussion Topics:
- Do you agree that these two motors could be used in this application? If so, what motor out of these tow you would chose?
- DO you think by having a much Lower KV value i could avoid using a Gearbox?
- In the links of these two motors it can be seen that the motor Torque is 4.8 N.M. Does anyone know what is the torque of the SSS 56104/500KV Brushless Motor? ( i failed to find this information).
- Does anyone know Alien Power System? Do you know if they are Trustworthy?