I’m going to continue the discussion with them and see where it goes. Their reply is surprising and pretty lame for sure.
Classic flipsky response.
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It’s not clear that the KV is lower than stated. You are testing them under load, and if the KV was higher, you would have less torque per motor amp, so your top speed under load could be lower even if the kv is higher. That’s why you haven’t actually determined whether the KV is different than advertised. For example if your top speed was limited by wind drag before (& not by back emf voltage as would be the case unloaded), then switching to a higher kv will give you a lower top speed, because you will have less torque at the same speed. So I recommend testing the actual KV unloaded by putting the board upside down on a test bench in BLDC mode, multiply the max rpm by 1.05, then divide by the battery voltage you had during the test.
PS the loaded speed estimate based on a generic “efficiency” parameter of 90% in the ESK8 calc is misleading. you would actually need to know the motor current and battery current limits, winding resistance, quantity of motors, whether it’s FOC or BLDC, frontal area, drag coefficient to get a reasonable estimate of the peak loaded speed on flat ground in most cases, especially when you want to go fast. for example if your top speed is limited by wind drag, simply switching to a higher kv will make you slower, not faster as the calculator estimates with a “generic 90% efficiency” parameter.
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I will have to try again with a USB connection but unfortunately when I tried to set it to BLDC through VESC Tool via Bluetooth or through Metr, I got errors trying to write the motor config. In VESC Tool it said something about motor type not being compatible or something like that.
Despite that, I should be able to test setup A vs setup B with the same settings and I would hope they should be similarly off from the calculated values. You’re right that such test should be on the bench to be more accurate.
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You don’t know whether both are mislabeled so unless you measure both a comparison is probably meaningless.
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