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  1. #1
    RC Racer
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    KiloVolts on Brushless motors vs Volts on Brushed Motors

    I am looking at the Titan 550 motor, and the specs say it is a 14 V motor. I am also looking at a brushless motor and the specs say it has 1800 Kilo volts (KV). Am I reading/understanding something wrong or is that they way it is?
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  2. #2
    RC Qualifier
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    If memory serves me right I believe on a brushless motor for every volt applied the motor will spin at 1800rpm. So at 11.1v or 12.6v for a fully charged 3s lipo that would mean the motor would spin 22,680rpm at the shaft unloaded. Up the voltage and the rpm goes up. Not sure how they measure brushed motors, but I think itís by turn. Hope this helps.

  3. #3
    RC Racer
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    Quote Originally Posted by TITANIUM94010 View Post
    I am looking at the Titan 550 motor, and the specs say it is a 14 V motor. I am also looking at a brushless motor and the specs say it has 1800 Kilo volts (KV). Am I reading/understanding something wrong or is that they way it is?
    Brushed motors are rated by their designed max voltage if memory serves me correctly.
    Brushless motors use KV to tell what speed they will spin.
    1V x the KV of the motor will be how fast it spins.
    So 2200kv at 10v would spin 20,000RPM.
    Some companies do rate their brushed motors in KV also, to make the comparison easier.

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  4. #4
    RC Turnbuckle Jr. Greatscott's Avatar
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    Quote Originally Posted by TITANIUM94010 View Post
    I am looking at the Titan 550 motor, and the specs say it is a 14 V motor. I am also looking at a brushless motor and the specs say it has 1800 Kilo volts (KV). Am I reading/understanding something wrong or is that they way it is?
    Nope, that is pretty much the way it is...

    There are two primary ways that motors are rated, turns and KV.

    Turns...
    • When you see a turn rating, "21-turn motor", that is the number of windings in the rotor. The lower the turns the faster the motor will be, but it will have less torque. That is why higher turn motors are better for crawlers and scale rigs. When you seen a motor with a ".5", it means brushless sensored, i.e.: 17.5 turn motor.
    • Turn ratings change depending on the size of the motor. A Traxxas 12T 550 motor is about the same rating as a 21T 540 motor.

    KV...
    • KV is a bit easier system to understand, it is simply the number time voltage, i.e.: 1900kv is the RPM at 1 volt. The basic understanding here is that higher KV motors will have more speed, but less torque (sound familiar?).

    Traxxas puts "14V" on there motors, this is not a KV rating, it is just the maximum voltage that the motor was intended to run under.
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  5. #5
    Traxxas Employee TireSlinger's Avatar
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    Quote Originally Posted by Greatscott View Post
    A Traxxas 12T 550 motor is about the same rating as a 21T 540 motor.
    I would say the Titan 12T 550 motor is similar to a 15T 540 motor. At least that's how the XL-5 ESC is rated, 12T at 550 or 15T at 540.

    Back in the day when brushless was new people didn't understand the KV ratings, so you would see someone running a 9000kv motor with a huge pinion gear and overheat things. Manufacturers started equating KV to "Turns" so users would understand that a 9000kv motor was similar to a 4 turn (or so) brushed motor. In other words, go small on the pinion because it's a very high RPM motor.
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