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  1. #1
    RC Racer
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    Can someone explain KV in laymans terms

    Im fairly new to rc and dont understand KV or "turns" in a motor. Why would you want a high kv apposed to a low kv and what difference does it make how many "turns" your motor has, is more turns better? or less turns? oh, and poles... please explain poles also. this may sound funny comming from a 34 year old, but explain it like your talking to a 13 year old please. Im not dumb, but I am VERY lost and would REALLY like to understand this stuff, then I can explain it to MY 13 year old .....thanks

  2. #2
    RC Qualifier
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    lower the KV the higher the voltage you will need, higher KV will need lower voltage. I'm not that up on brushless stuff, but thats what I know about that. For brushed and turns, the lower the turns, the faster the motor will be, there are also types of windows like single double quad etc. i believe single has more torque than quad does. Brushed stuff is really old, not really relevant with todays technology.

  3. #3
    RC Racer
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    I'll explain KV if you explain Google ;-)

    http://www.rcknowhow.co.uk/blog/2011...atings-basics/

    "The KV rating is quite simply the number of revs per minute the motor will produce per Volt of electricity thatís applied. So a 3000kV brushless motor will output 30,000 rpm when you apply 10 volts to its terminals."

    As for poles (this from a short thread at URC)

    "More magnet poles means more switching in the esc as the polarity changes more often for a single revolution of the rotor. That can create extra heat in the esc but good quality esc's can handle that. The advantage is that the higher pole count motor will feel "smoother" in the torque department and has a little natural braking as well off throttle."

    Others more knowledgable people may wish to may want to chime in but this is what I took away from this and other reading......

    • Kv Rating is the number of revs per 1v applies
    • High KV = High Top Speed / Low Torque
    • Low KV = Low Top Speed / High Torque
    • 2 pole = Lower Torque / Lower heat (in the ESC)
    • 4 pole = Smoother/Higher(?) Torque / Higher heat (in the ESC)


    I'm still not 100% on the Higher torquue with 4 poles. I now run a 4 pole 4000KV motor in a 2WD slash (on 2S only) and it rocks.

  4. #4
    RC Champion
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    as stated above,

    KV rating on a motor is theoretical RPM per volt.

  5. #5
    RC Racer
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    with brushless motors do the "turns" still matter, or is the kv rating the only important stat? how do the 2 stats work together?

  6. #6
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    low turn=higher speed lower torque. higher turn=lower speed higher torque.

    Turn is related to the winding in the motor - path the voltage travels. shorter travel path (low # windings), faster motor spins.
    Stats are separate....mostly. Typically, you'll see a higher turn with a lower KV rating and a lower turn with a higher KV rating. Basically, KV is related to turn in this way. thats all I can speak to.

  7. #7
    RC Racer
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    can you over rev a motor? if so, how would you know if you had a setup that would over rev? how would you avoid it? what would happen if you did over rev?

  8. #8
    RC Racer
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    does any one make a high turn high kv motor? or low turn low kv motor? or would that not work???

  9. #9
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    In a brushless motor an over rev would create heat, IE overheat. But under rev will also create heat. So you have to gear and watch your temps. Also alot of bl motors will have a max rpm, so you would have to choose voltage accordingly.
    Rusty 2.5R,T-max 2.5 & 3.3,Summit VXL Nitro 4-tec

  10. #10
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    Just an FYI, Turns have no correlation to Kv. Turns is used to describe the number or turns of wire creating the coil in the motor. Kv is the RPM per volt. Now with turns (usually used for brushed motor rating) the wire can be very thin or can be very thick and this affects the rpm. IE a 15 turn with thick wire will have a different rpm from a motor with 15 thin turns. The accepted max rpm on brushless motors is 60,000rpm, some high end systems can take more. Multiply your battery voltage by the motors Kv rating. I run 2s lipo(8.4v after a full charge) on a 6800kv system, so it's spinning up at 57,120rpm (without any load or voltage drop)
    Dye-no-mite Pow-er Go Fast, Wirrrrr Screeeech BOOM

  11. #11
    RC Turnbuckle Jr.
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    Which you will always have load and voltage drop!
    Plus with a 60,000 rpm motor its not good for the motor to run that rpm all the time if ever. Better to stay in the 30-50k range

  12. #12
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    whats the max rpm on our vxl setup???

  13. #13
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    50k rpm
    10 letters
    summit /mustang /stampede-2s spc lipo

  14. #14
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    im running stampede tires a 55 spur and a 29 or 30 pinion, on 3s lipo, its got pretty hot until i installed a fan and heat sink. do you guys think im over or under revving mine????

  15. #15
    RC Racer
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    what kv size motor would you suggest ? I like to go fast, but normally im in a confined area so i dont ever really get a chance to get to top speed much. I was plannin on getting the gottogorc motor esc combo for christmas.

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