KV question

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Wheels007

Wheels007

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Corally RC's
  1. Sketer
I have two motors of the same can size, but one is 2150 kv and the other is 2600 kv. Which has more torque/ less prone to over heat?
 
Kind of a loaded question. It’s like “I have 2 V8 engines a duramax and a built 350. which one will make the trip up the mountain better?” 🤣. I think it will depend on other variables which is best for your uses. 🤙🏻
 
project_revenant said:
Kind of a loaded question. It’s like “I have 2 V8 engines a duramax and a built 350. which one will make the trip up the mountain better?” 🤣. I think it will depend on other variables which is best for your uses. 🤙🏻
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I guess it could be sumd up like, heavy=lower kv, light=higher kv?
 
Basically lower Kv means less rpm with the same voltage. 3.7v x 2150kv= 7955rpm 3.7v x 2600kv= 9620rpm. So that’s 2021 rpm less per cell “with standard LiPo”. So my question is how do we get more torque with less kv? In theory couldn’t we use higher kv and just gear accordingly? Or is that too much strain in the system. I do believe the rpm limits of the motors play a huge role in the decision making as well.
 
project_revenant said:
Basically lower Kv means less rpm with the same voltage. 3.7v x 2150kv= 7955rpm 3.7v x 2600kv= 9620rpm. So that’s 2021 rpm less per cell “with standard LiPo”. So my question is how do we get more torque with less kv? In theory couldn’t we use higher kv and just gear accordingly? Or is that too much strain in the system. I do believe the rpm limits of the motors play a huge role in the decision making as well.
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Honestly, it goes over my head..theres different winds, with different targeted rpm ranges ect..
 
Interesting topic! A higher kv motor has lower turns, that is, fewer turns off wire inside the motor and because of this there's less resistance and higher speeds. A lower kv motor has more turns which means more resistance and lower speeds, but also a stronger magnetic field and this is what gives more torque. The strength of the magnets inside the motor also plays a role here of course, but assuming you motors are of equal specs and the only difference is the turns then the lower kv one has more torque.
 
project_revenant said:
Kind of a loaded question. It’s like “I have 2 V8 engines a duramax and a built 350. which one will make the trip up the mountain better?” 🤣. I think it will depend on other variables which is best for your uses. 🤙🏻
Click to expand...
Duramax will always win... lol.
 
project_revenant said:
Basically lower Kv means less rpm with the same voltage. 3.7v x 2150kv= 7955rpm 3.7v x 2600kv= 9620rpm. So that’s 2021 rpm less per cell “with standard LiPo”. So my question is how do we get more torque with less kv? In theory couldn’t we use higher kv and just gear accordingly? Or is that too much strain in the system. I do believe the rpm limits of the motors play a huge role in the decision making as well.
Click to expand...
Also what about different grades of motors, example: if you had high end 2150kv and a cheap motor 2150kv wouldn't the high end have more rpm ?? therefore giving more power, not sure would that be torque or speed ??
A stock TpPower motor will normally have a rpm limit of around 60000 rpm whereas a cheap motor may only be 45-50000 rpm..!!
What happens then 🤔
 
BashingBrian said:
Also what about different grades of motors, example: if you had high end 2150kv and a cheap motor 2150kv wouldn't the high end have more rpm ?? therefore giving more power, not sure would that be torque or speed ??
A stock TpPower motor will normally have a rpm limit of around 60000 rpm whereas a cheap motor may only be 45-50000 rpm..!!
What happens then 🤔
Click to expand...
My understanding is the high end motor will be more likely to run at the advertised rpm, the lower end less so,ie, I've heard the blx/spectrums typically run slower than advertised by as much as 200rpm. Don't quote me, I don't own an analyzer,but I know I've read it somewhere.
Then QC comes into play, quality of materials, assembly and so on.
The actual rpm rating isn't a big deal, you never really want to hit max rpm anyway as the top efficiency of the motor is generally at lower than max rpm.
 
KnowAir said:
Not biting..😬🤐🤣

JK, a brand is a brand..if it works, I like it👌
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Thats funny, I was really thinking about diesel vs gas, but I am a Chevy guy. Having said that, I wouldn't turn down a Cummins or Powerstroke either!

KnowAir said:
My understanding is the high end motor will be more likely to run at the advertised rpm, the lower end less so,ie, I've heard the blx/spectrums typically run slower than advertised by as much as 200rpm. Don't quote me, I don't own an analyzer,but I know I've read it somewhere.
Then QC comes into play, quality of materials, assembly and so on.
The actual rpm rating isn't a big deal, you never really want to hit max rpm anyway as the top efficiency of the motor is generally at lower than max rpm.
Click to expand...
Also, the lower quality motors use lower quality bearings, lower quality copper for the windings (which increases I2R losses) which all contribute to higher temperature motors and lower RPM's. At least that is what I have read.
 
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