Let's talk about torque ( and KV's )

[BashingBrian]

So my question is about torque..!!
I'm no rocket scientist but at the same time I'd like to think I know a bit about stuff and things
But answer me this, what makes torque and why do lower KV motors have more torque ?? I understand the long can, fat can torque benefits.
In general though why do low KV motors have more torque..
Let's torque....

 

[Outcastblxnut]

Because they just do

 

[Grimbles]

In general though why do low KV motors have more torque..

Witchcraft?

 

[JvG]

So my question is about torque..!!
I'm no rocket scientist but at the same time I'd like to think I know a bit about stuff and things
But answer me this, what makes torque and why do lower KV motors have more torque ?? I understand the long can, fat can torque benefits.
In general though why do low KV motors have more torque..
Let's torque....

A lower kV motor has more windings. The electrons have to travel a greater distance but more go through the total windings in the motor so it turns slower but has more torque.

 

[Camaroboy383]

So my question is about torque..!!
I'm no rocket scientist but at the same time I'd like to think I know a bit about stuff and things
But answer me this, what makes torque and why do lower KV motors have more torque ?? I understand the long can, fat can torque benefits.
In general though why do low KV motors have more torque..
Let's torque....

More winds of thinner wire on lower kv rotors... Carries more voltage with less amp load...

 

[AIan]

Just cause
That’s what everybody said

 

[Cheez]

http://rcboats.kiwi/index.php/ct-menu-item-15/ct-menu-item-31/ct-menu-item-43

 

[JvG]

Another question:

same car, same speed. Let’s say k8s exb at 50mph.
What’s the difference between a higher kv motor with a smaller pinion or lower kv motor with a larger pinion?

 

[Lefty_Al]

higher kv motor needs more RPM to make the same speed as a lower KV with larger pinion.
at a high level
Speed = final gear ratio * motor RPM

if you lower the pinion you need to increase the RPM to keep the same speed.

 

[JvG]

higher kv motor needs more RPM to make the same speed as a lower KV with larger pinion.
at a high level
Speed = final gear ratio * motor RPM

if you lower the pinion you need to increase the RPM to keep the same speed.

Yes correct but what's the difference in power usage, heat production and acceleration, if any......

 

[Lefty_Al]

Yes correct but what's the difference in power usage, heat production and acceleration, if any......

Hard to say without some specifics on the motors in question. I suspect the lower kv will run cooler but likely be able to pull more current under acceleration.

 

[Yonic]

Another question:

same car, same speed. Let’s say k8s exb at 50mph.
What’s the difference between a higher kv motor with a smaller pinion or lower kv motor with a larger pinion?

as i understand it, theoretically there's no difference. but practically you'de have a motor that is more effecient in a specific KV then the other, so the option that uses that KV would be more tourqy/cooler/efficient.

 

[Jerry-rigged]

Higher KV motors (In theory) make more total power. Lower KV motors make less power, but more torque.

Also realize - if both motors are geared for 50mph, they will make the same amount of power and heat.

This all assumes same motor size, same voltage, etc.

 

[rotauq]

Kv is like the internal gearbox. Changing your gears to get the same speed does output roughly the same power/torque. Same can, same potential. It's either optimized for high volts(low kv) or high amps(high kv).

Not gonna throw in formula's but Kv and Kt are both (no load) constants. On some previous thread it was concluded low kv has an almost neglectable advantage in torque.

On the other hand once you go in extreme's you'll find the lower the kv the thinner the wires, and thus the maximum amp's it can handle. Not a problem when you go for keg-sized motors but at 36/40mm it's notable.

A low kv motor will be slightly more torqy and definitely will be more efficient under average load. But a relatively higher kv motor can take more of a beating for having slightly higher thresholds, potentially giving you that little extra you were looking for.

 

[The Bean]

"So in the end, it doesn't even matter"

- Chester Bennington

 

[rotauq]

"Pushed as far as I can go"

- Chester Bennington

 

[The Bean]

"It all fell apart"

- Chester Bennington

 

[Monster Dork]

The thinner wire will bleed more heat if the current is constant. Low KV motors have higher internal impedance. In theory, anyway. I suspect that in our applications, in practice it's neither bad nor good. It just is.

 

[The Bean]

Thicc wires have less resistance --> should give moor powa

 

[Monster Dork]

Not necessarily. This is an AC motor, so you're dealing with reversing magnetic fields, lots of physics comes into play that you wouldn't even consider for a DC circuit.