I’ve been thinking recently, what are some reliable ways to test a VESC or other ESC? manufacturer specs are great to have and sure we have the ESC based on VESC list for that but what about more realistic data? we know most china VESCs can’t actually handle their full advertised current load. I want to figure out a good way of testing a VESC to find out its true limitations much like @Battery_Mooch tests cells (in spirit, the methodology would obviously be different)
I guess a benchtop PSU and oscilloscope would be primary tools, would that be enough to test phase current and supplied current?
it would also be beneficial to see data around current spikes, hall sensing data and other factors. it will help separate the quality VESCs from the bad ones and make new DIY-ers jobs a lot easier with VESCtool settings.
Addn: I feel like I’m missing an old thread here as I can’t be the first person to think about testing ESCs…
I will add this, then, since you deleted your original posting of this.
It depends on what you’re looking to test. Generally, any test that you want to be representative of a situation for a certain device, needs to approximate said situation.
If you’re just testing whether or not a specific ESC can sustain X amount of amps, then generally you would use FOC open loop into a motor that can handle that current, and then monitor thermals.
Since that generally still leaves the battery in current relatively low, you could then set up a dynamometer to simlate torque load on a motor at a certain RPM, and funnel that back to require more current draw from the battery.
A power supply likely isn’t going to be able to provide 50-75v at tens of amps, unless you’ve got quite the budget. So a battery of a representative size would be appropriate.
Generally, most folks who are interested in testing such things simply use the most practical test jig available, which is an actual eskate they’ve built, and then substitute the part in to test.
Of course, that’s dangerous should the part fail, but it’s usually cheaper for someone who doesn’t have a whole shop’s worth of stuff to make testing jigs.
You could also design a specific PCB based testing jigs like what Future Motion does, but that takes engineering talent and money.
Adendum: DIY builders with enough reading, collaboration, and expertise in the parts they employ, generally have a reliable starting point for almost any application, since all of these parts and systems are based around the same philosphies of design.
Those who choose to push beyond those conventions do so at their own risk, as is the nature of testing things in any sense. @Takachi14 has an affinity for pushing insane amounts of current everywhere under his feet, and @Heathlewis I imagine has some expertise when it comes to testing the real world limits of the sheer RPM thresholds for his parts.
Every build is a test jig for something.
The best data comes from the community, as each member tries something and gives their data.
The best thing that I have ever found in helping to grow knowledge and expertise, is to actually read what the community says, and actually listen to it. Just a general thought.
Like Mario said you’d need to set up a whole test apparatus. Testing ESCs would be pretty difficult too because you need something to consistently apply a load if you really want them to be loaded. The “simplest” thing I can think of is to get a brake disk and caliper, connect that to your motor, and adjust the brake pressure until you get a consistent RPM and load that you want to test at. Even then it might need to be pretty beefy to be able to do a long continuous test. The brake would have to handle something like 10x more heat than the motor since motors are something like 90%+ efficient. That is basically a type of dyno, but you’d be adjusting it by ESC load instead of actually calculating the torque. Calibrating a friction brake dyno is not an easy task I don’t think, but I’ve never looked into it a ton. There are also eddy current dynos, generator dynos, and some other things, but I think brake would be the easiest to jerry-rig yourself. I guess the generator also wouldn’t be that difficult, but you’d need a giant electronic load or something to put power into.
I definitely agree @TheBoardGarage that every build is essentially a testing jig for any part, but as you said that’s pretty dangerous if you’re pushing limits, not only for the rider but the parts can be damaged too, not just the one being tested.
A fully dedicated testing jig seems like the right move. Even if I’m not liquid enough to build one right now I’d like to figure it out for thought experiment sake.
A tachometer does seem like a necessary part.
Instead of a disc brake, what about another motor and ESC applying an electronic brake? Then I could monitor BEMF generated in the slave motor while the motor or ESC being tested applies RPMs
For current and voltage I figured a PSU would do better, as a battery drops in voltage as it’s depleted and the supplied current also lessens over time whereas a PSU of appropriate spec could supply it consistently.
Sorry, I moved it to it’s own thread as it seemed to be in a wrong-ish place before.
To get something like a 60V 60 Amp PSU you’re going to spend a ton of money or have to make your own. Those are not normally lab equipment people just have around.
On top of that, you’re talking about ~3.6 kW. A standard US circuit breaker is only like 1.8 kW. If you want to really push high-end ESCs you’d want something more intense. You want to test 20s ESCs? Then you need at least 84 V you’d end up needing something along the lines of https://www.digikey.com/en/products/detail/astrodyne-tdi/T100108057-1-LF/13617962 or something which is $8k and even then you can’t max the current of certain ESCs. That would probably be “good enough” though.
Also, I’m pretty sure most ESCs would blow up if you tried to do a couple of kW of braking with them and you’d need a load they could put all that energy into which also costs money. I’m not actually sure what the max braking power ESCs can handle is.
Alternatively to using one ESC to brake, you can couple 2 motors to each other (belt drive is probably the easiest) drive them forward so they’re fighting each other while both consuming current and not storing any energy while you can run the load at a constant current and the driver at a constant current.