Kv Ratings on Brushless motors

[godale03]

Hey Guys,

I made a mistake earlier today by mistaking a 4300Kv motor for a 4.3 motor, therefore thinking that that motor was hotter than a 5300... of course which I mistook for a 5.3 motor. I have also found out that Novak, the brushless motors I am the most familiar with, used to classify there motors differently than they do now.... ie. a 4.5 motor is hotter than a 6.5 motor. So I guess my questions are... how do you find out how many Kv a motor is? What does this number mean?, and How do you use it to figure out if it is the right mill for your application? Thanks



Tom

[flm_savage]

lower motor number = higher torque and the ability to run higher voltages.
higher motor number = lower torque but more rpm per volt. normally won't accept higher voltages.

that said, i run a 6900kv in my firestorm. I would have gone with the 5700 but i only wanted to run a 7 cell pack and run time isn't crucial to me. So i got super fast with decent torque and average runtime.

[Lessen]

I believe.... "believe" that the Kv rating is basically equal to RPM per Volt with no load. So your 4300 Kv motor would turn at 30,960 rpm (4300 x 7.2) at full throttle with a 7.2v pack under zero load

[godale03]

Man... I have alot to learn. I thought the 4.5 would be the Kv rating. Thanks for the info guys. I will hit the books an try to educate myself with the proper information.

[Lessen]

When it comes to the Novak motors I believe the number of the motor (in this case 4.5) is relative to the Kv rating. I think that motor has a Kv rating of 4500.

I think what has you twisted is that you are used to knowing that less turns (lower number) = hotter motor. However, with brushless motors the higher number will give you more top speed.

[godale03]

Originally Posted by Lessen

When it comes to the Novak motors I believe the number of the motor (in this case 4.5) is relative to the Kv rating. I think that motor has a Kv rating of 4500.

I think what has you twisted is that you are used to knowing that less turns (lower number) = hotter motor. However, with brushless motors the higher number will give you more top speed.

Yup... I am sure that is what I am confusing. Just going to take some time I suppose. I just appreciate you guys not hanging me for sounding like such a dumbass.

Tom

[Lessen]

Dont' sweat it man. For the past 3 years I thought you couldn't fast charge Nicd batteries. *buzzer*... wrong. Nobody knows everything.

[godale03]

Originally Posted by Lessen

Dont' sweat it man. For the past 3 years I thought you couldn't fast charge Nicd batteries. *buzzer*... wrong. Nobody knows everything.

In my case sometimes I think I know nothing! Things change so damn fast these days. It's hard to keep up.

[Brushlessboy]

The lower the number on the Novak systems, the faster the car will be. The 3.5 Velociti has a Kv rating of 10500 revs per volt, while the SS 8.5 Pro runs only 5000.
You can get 2.5 turn motors but the quality of Novak sees no real difference in the REAL power results.

[Lessen]

Dont' they realize that they are just confusing people with these stupid number ratings? Why can't they just call it Velociti 10.5?

[CharliesTheMan]

well it's kinda like a Chevy 350 small block having 350 cubic inches, 290 horsepower, and 325 lb/ft of torque. Different numbers for the size and power rating.

[Brushlessboy]

Here Here Lessen! In both Nitro and Electric the numbers are confusing, and real outputs unknown unless you chase down manufacturers websites.
I am SURE they could all give us a clue in the model name.
Or maybe I'm just missing something!
Just to confuse you even more. The Velenion system that comes with Traxxas VXL's has a rating of 10.5 turns, (according to Traxxas) but absolutely EATS my 8.5 turn Novak.
GO FIGURE.......

[CharliesTheMan]

Well thats kinda like the os .21 that would eat the picco .26 isn't it?

[Brushlessboy]

Spot on again Charlie, but I've never understood how you can TUNE an electric motor.
I though electric either worked or it didn't!!!!!
(not real clever but I can lift heavy things)

[Lessen]

yeah, there really aren't very many standards in the power world of r/c. Definitly when it comes to dyno there is no consistancy. One mag says one thing, one says another. I've read more than a couple articles on inconsistancy within the industry.