Electric motorcycle motor choice

Friday

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Jun 25, 2020
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I am trying to find a motor to take me and about 70kg of home made motorbike up to 100 kph (62 mph) in about 9 sec. I need a top speed of about 130 kph (81 mph). I want something sealed so it does not fill with road grit as it will be mounted to the rear swingarm.
I am looking at NeuMotor 4430 (https://neumotors.com/neumotors-4400-series-bldc-motors-1000-to-4000-watt-class/#4440)
Any ideas on how many windings to select? They vary from "4430/3Y" to "4430/.5Y" with max volts/amps varying from 333V/90A to 51V/585A.
Planning to make a pack of about 600 Samsung 30Q 18650 cells to power the motor. Obviously they will need to be configured differently depending on windings selected.
As far as I understand (not very far!) performance would be similar with any of the winding options but what options can I get a controller for and what would is most likely to give me an affordable, practical build.
Any help appreciated!
 
So I think I'm set now on the Neutronics 4430/1Y (https://neumotors.com/neumotors-4400-se ... lass/#4440).
(I wonder does that mean 1 turn?).
If I were to operate that with the 600 cell battery pack at 24S/25P, the controller would see up to 100V and the motor would draw up to about 100 A continuous and up to 210 A for say <10sec. I used the eCalc Torquefinder calcuator on the neutronics website and it showed the motor coping ok with my demands.
From Neutronics for 4430/1Y:
kv 97 rpm/V
kt 0.10 Nm/A
I0 3.0 A
Rw 0.01 Ohm
I_max 291 A
Vmax 103 V
rpm_max 9991 rpm

Controller:
The Neutronics site recommends an HVPro24 controller fro Advanced Power Drives to drive the motor (https://neumotors.com/apd-hv-pro-24-brushless-esc/).
It looks serious but is probs more RC oriented than I need. The thing weighs only 200g, whereas my motorbike won't care if the controller weighs 1.5kg. Also, I'm sure its worth the $1250 USD for that application but is there something that would work better for my application? Also, will I need to add sensors to my motor? That sounds really hard.
 
You'd almost certainly need sensors. One way to accomplish this is a Timken setup for the 12 poles of the Neu 4400 series. They're available here: https://www.timkenencoders.com/en-us/m15h-high-resolution-modular-magnetic-encoder . I have yet to try these encoders. But I plan to use them on a very similar engine made by Astro, and they were recommended to me by the Astro Motors people. As long as the Neumotors has enough of a rear spindle (like a 1/2"), you should be able to mount the Timken without having to open up the engine. Look into the details, though. As for controllers, if you do use an encoder or hall sensors, then you'll need a controller that recognizes them. An ASI controller like the BAC-X000 series can do this. They handle up to 72 volts.
 
Are you sure you can build a reduction drive to get your 10krpm down to something useful at the wheel? Typically you end up adding about the same amount of weight in gear reduction parts as you would have just using a larger motor that isn't on the verge of becoming a fireball the whole time. In my opinion your speed and power goals sound almost impossible with a 3.7kg motor. Those power ratings are behind a massive fan on an aircraft. That is also not a traction application. A motor pushing a prop wont instantly peak out at high amperage and melt like a motor turning a wheel with traction.

Everyone I have seen use a neumotor on this forum has needed to repair shaft issues and or re-balance the motor right out of the factory. You are going to need to spin it super fast to get anywhere near the power you are looking for. So bearing and balance issues are going to be a factor. Also at super high rpm the bearings in your gear reduction are going to heat up.

I'm not trying to be mean and shoot down your whole plan. If you can engineer it and pull it off I'd cheer you on but this is a very optimistic goal with such a tiny motor. The closest comparison to what you are after is matt shumaker's builds and I don't recall him gearing any of them for 80mph.

Have you looked at the QS mid drive motors? Lots of people are having good luck using the 3000 watt motor on motorcycles with the type of weight and acceleration you are talking about. It could be done with no complex gear reduction and at a much more reasonable RPM.
 
Are you sure 24s is a good idea?
Many controllers use 100v components and can handle about 85v or up to or a little over 90v if you want to push it.
I think 20-22s is a good idea in that case. Or you can go for a (more rare) controller that can handle more, but in that case no reason to go for just 24s
 
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