Building a motor-to-motor dyno...

So unlike within the ebike market, I’m not seeing much for load testing/dyno graphing motors for high-speed outrunners like we use on boards. Given the general availability of twin-motor ESC’s these days, I’m wondering… Why not build a motor-to-motor load dyno? Has no one done this already?

I’d like to be able to build a test jig and compare various motors I’ve bought over the years for efficiency, torque, heat shedding capacity, etc…

So if I’m not duplicating someone else’s work already, let’s start figuring this out.

Let’s start with some thoughts and questions I have:

As motors heat up, they lose power. This goes for both the input and “load” motor, in the case of a dyno setup; I have two options here:
A: Find and profile a “big” motor that has far more torque/power capacity than what I will be testing, profile it’s efficiency and loss profiles, and factor those out of further tests.
B: Alternatively, test two identical motors against each other. The thought behind the latter is that any running losses from heat would be identical between input and output. I don’t know if this is sound logic, or if I’m introducing further unknown variables into the mix rather than controls.

For now, I’ll be reaching out to to see if I can glean some info from their dyno setup and see where I need to take this. If anyone has thoughts, suggestions, or examples of existing builds, please let me know.

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Following! Some of my buddies and I want to build a dyno for boards

and not motor to motor. Tires to something to something to motor maybe.

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Yeah but the info he comes up with here might still be useful

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:100: agree.

naively to me it sounds like a good plan. motor as load and measurement. vs more complicated hydraulic setup. or non measuring physical brake setup.

Here’s the thing about a motor-motor dyno; you can measure power in and power out, and they don’t have to directly couple; you can connect a gearbox to measure efficiency loss, or whatever else you want to test.

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