Today It was suggested to me that people who upgrade just their motors to larger motors get more torque with the same motor amp settings. backed up with experiences of both bikes and esk8s doing this and feeling more torque.
My understanding is that motor torque is proportional to motor amps x Kt. (torque/amp) and that Kt is inverse of Kv. (it’s 1/Kv) so a larger motor of the same kv maybe able to handle more motor amps, but with the same motor current it’s torque should be the same.
Am I wrong? is there some case where both these things can be true? maybe the smaller motor loosing some effeciency due to heat?
You’re right, though I think it’s easy to make the wrong assumption if you don’t think too hard about it. More bigger = more better.
As far as I understand, the efficiency and heat thing actually goes the other way: large motors have higher parasitic losses and are less efficient, but I’m not sure to what extent
Can handle bigger current. My 6355 (marginally) beats a 6384 at 65A, but the 6355 just can’t push 80/90A without a Bad Time, so if you want to do that you’ve gotta go bigger
Lots of pretend experts out there that don’t use data or formulas at all to form their opinions. “My buddy said it made more torque and he knows a lot” is usually the most amount of data they’ll use for their claims.
A rebranded sealed maytech, 170Kv. I used to run it 56 because of a typo, and changed to 65 a week or so ago. Very unscientific small sample size etc, but I didn’t feel a noticeable increase in heat
damn. I have the old FS 6355 and on a warm day after a run on 45A they are too hot to touch. No idea how hot they really are because they don’t have temp sensors though.
Firstly, most of these people are probably switching mfg’s so the comparison likely isn’t direct, slight KV differences and stuff like that will effect things a little.
But I think one of the only plausible reasons they could be feeling more power is if they are hitting thermal reduction and then with the larger motor thermals are much better they’re no longer having the power reduced. Otherwise, I don’t see much of a reason for that claim.
dunno if there is other reasons behind this but… (im no expert so you tell me why)
2wd 6355 metr logs tell me the max amps on startup was roughly 30amps per motor (battery amps)
2wd 6374 metr logs tell me the max amps on startup was roughly 50amps per motor (battery amps)
not exact numbers (rounded slightly) and they were both up the same hill.
both motors were flipsky
both times it was up a steep hill and pretty much full throttled it.
i def felt more torque with the 6374s also
the 6355s didnt get hot (like ouch hot) but the end of the hill and were set to allow more amps (all the way to 60amps)
could be ive made an obvious mistake here though (of why this happened)
so say you had flipsky 6374s at 100A. and upgraded to 63100s thought it felt like more torque, even when the 63100 was lowered to 80A? this is one of the anecdotes.
how would you explain that?
just real KV differences vs stated KV differences? which is what I suspect?
or can something like the 6374 be oversaturated and performing worse than it would have it was at 80A?
is it possible that running the 6374 at 100A over saturates it and it somehow does worse than it would have at 80A (it’s rating).
No, unless youre using vesc, because vesc torque efficiency drops exponentially with current due to poor tracking in sensorless with increasing current. This is the cause of that doggone torque pickup effect everyone gets.