A dyno can’t be everywhere though and requires everything come to it, but with the vesc and if we came up with a standard test it’d be just as good maybe - Distance to watthours consumed at different speeds. At higher speeds air resistance and the rider profile becomes important but with similar sized riders in the same position should be pretty good
I mean we build a dynamo that can be 3D printed or laser cute for a nominal price AND supply a motor with known constants so we can ALL study motors with something of a standard.
That would be great and not so hard, my plan for now is to build a inertia dynamometer, the downside is that we can only obtain the torque curve, but not test at a fixed rpm/torque for long time, but hey, its cheap
It would be a start.
With some work, we could repurpose old VESCs to create a variable load for standard testing. Plenty of programming memory!
What are you proposing?
The Action Blink 4WD will be interesting. I look forward to mine in March. It’ll give me hope and something to improve on. It’s a pro version of what we already have developed as a community.
Like I said, I have a dyno and the software is on trial but if/when I buy it it’s $500. Highly discourage 3D printed dynos. Fast spinning objects + heat + plastic + inconsistency of 3D print asking for injuries and frustration.
I’m totally willing to setup others motors. There is some cost in adapting others motors to my setup… easiest would be to have a complete wheel with urethane ready to go. I can load up to at least 2kW for short periods. Resolution is 0.00263 Nm at 2.5Hz or 0.036 Nm at 200Hz, up to 50Nm. I’m in LA, just ship me your shit.
I might have a christmas surprise for you all if parts arrive on time, however I will probably be thermally loading it with field weakening until my urethane is made properly.
I would like to see a sub 700 gram hub motor that is still useful and doesn’t get too hot. I hope my design fulfills that goal, although to get to that point I think I will need some thermal FEA software.
There lacks innovation in winding / copper fill optimization, largely because there hasn’t been a need for high powered micro motors because most people just make it bigger and accept the huge weight and size and bulkiness difference. If you can get 90% slot fill with most of these hubs, you’re in happy place. I think 3D printed motors are the future… Where you have the machine sintering copper and silicon steel in one operation, adding gaps between winds to create your insulation.
Thanks, @Hummie. Yes, our torque curve remains flat at 7Nm until around 28 kph - dropping to 5 Nm at 40 kmh. This is total torque so divide by 2 for one motor. We’re at 70% implementation of the full capability (don’t want to cook any more motors than we have; our last two months will be used wisely). Feedback from assembled testers (of different riding levels) is a mix of shock, awe and…fear. So we have come acceleration shaping and smoothing to do.
@Pedrodemio The instagram shot has a misspelling on the Excel tab; the efficiency graph was for a Boosted Dual+, not the Mellow. Our analyses with our dyno showed max torque of 9.8 Nm (total) and then a rather steep descent to 0Nm at 35 kmh making it hard to see where field weakening starts. Max mechanical power output was 820W. The cells are capable of 70A continuous, but the system of course never goes that high.
BTW, anyone else playing with dynamic field weakening?
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The Action Blink 4WD looks like having the ready made Chinese motors on. They just look 100% the same. Urethane is just a bit different… I thought: Well, they just made some futuristic looking board, based on the Chinese stuff available, and cashed in. There is a lot of stuff like that going on on KS and Indiegogo. You just make your crowd believe… It works. http://winboardskateboard.en.ec21.com/
Frank
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Just building the market up for us. lol
80mm wheel or? I wouldn’t expect many complaints.
I saw that something was not adding up, the graph was too different than the previous one, if in the future after the release of Mellow you could release your hub efficiency graph, that would be great
Mellow should not be left behind a lot according to this data, maybe even pass when speed catches up
@Trillium 80mm wheel.
We’ve used the dyno to do for pre-builts what @anon94428844 is doing with you all here. We’ve done a full workup on efficiency, torque, power, etc for Carbon GT, Boosted Dual+, Onan X-1, Stary and an Evolve Pintail, and are very happy where we stand. @Pedrodemio As you have surmised: we do catch up to the Dual+ eventually. Our torque curves cross each other at 13 km/h. Hubs can and will compete with the belt drives performance-wise. We’ll release the charts in the near future.
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@Mellow Thank you for the support. In a product oriented community, its not often that we get support in development/pioneering a project, since its easier for people to criticize and throw money at problems.
So guys, its clear that we need a half decent bench testing solution we can all reference. Laser Cut aluminum or CNCed aluminum frame dynamometer. We need a community effort to build one for BLDC testing.
Boosted’s in house Dynamometer from their early days:
Preliminary VESC Based Dynamometer (DATED, but useful):
With the VESC 6.0, we can have higher resolution data from the motors we use in testing. While we wait, lets consider the best way to test motors by considering how to BUILD a rig for hub motors. We could build a custom can/rotor that connects to the shaft, but thats additional milling for every motor. A Wheel-to-Wheel test might work, but we have mechanical losses. I’m pretty good at AutoCAD and Solidworks, but I need someone to do the mechanical engineering here to reduce losses. Anyone with me? If so, PM me. Otherwise, I’ll create a new thread about a community driven Dynamometer.
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I’m in but let’s keep all open, and I can help on the mechanical part
In my opinion the better aproach to be cheap and easy and to make is to use friction, a bike disc brake and caliper, a load cell taken out os a cheap scale or bought, an arduino and we are done The vesc send info to the arduino, same for the load cell, with that info we can make a simple mechanism to apply brake, that can be manual or servo driven, on the latter we can make a routine to automatically generate a torque/current/efficiency curve
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That’s a great start. I like the idea of using a disk break instead of another BLDC.
I’m going to get some basic information together and start a thread tonight.
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Nice, we continue the discussion there to not go off topic
I think a generator would be better. It will be hard to use a disc brake as sort of standard. You want a well defined and measurable resistance. You need to know the output power to measure the efficiency. If you know your generator it’s easy to straights out the numbers. Define a cheap generator everyone has access to and standard is set. Mechanics should be easy to sort out. Some alloy and wood…
Frank
The programming will be quite simple, seen in the image bellow, we just have to test how stable is the torque using the brake
The test will be completely automatic and will generate in one run torque vs speed vs efficiency
I’m just a bit worried if the brake disc will end the test on a acceptable temperature, I think a big fan pointed at it will be needed and incorporate cooling time and stabilization time, or in another aproach, make each measurement so quick that it don’t have time to heat up, Just have to check if the data is stable in short periods or if we will have to round and filter it over a period of time
