Understanding V5 Smart Motor (11W) Performance

Smart Motor

The V5 Smart Motor (11W) had to be perfect for V5 to be successful. Thousands of hours of engineering and analysis went into designing this motor. Everything has to work together: the motor, gears, encoder, modular gear cartridge, circuit board, thermal management, packaging, and mounting. Users can control the motor’s direction, speed, acceleration, position, and torque limit.


Consistency is the name of the game. Software limits the motor's max speed, which not only makes the performance across different motors more consistent, but allows the motor to operate at max speed while under load. In fact, the motor is capable of running at max speed until it reaches about 60% of peak power (12.75W) or 35% of stall torque (2.1Nm).

The motor is also capable of producing 11W+ across 30% of the speed range, giving VEX Robotics Competition teams unprecedented power.

Internal circuit board

The (11W) V5 Smart Motor’s internal gear design has to withstand all the motor’s power, and the abuses of external forces coming into the motor from loaded arms and robot momentum. The gear train is our most robust yet. Metal gears are used in all high-torque locations for strength. Plastic gears are used in the low-load, high-speed locations for smooth and efficient operation. An internal gear cartridge is user changeable for output gear ratios of 6:1, 18:1, and 36:1.

The motor's shaft socket can accommodate 1/8" Drive Shafts as well as 1/4" High Strength Shafts.

The motor’s internal circuit board has a full H-Bridge and its own Cortex M0 microcontroller to measure position, speed, direction, voltage, current, and temperature. The microcontroller runs its own PID (proportional-integral derivative) with velocity control, position control, torque control, feedforward gain, and motion planning similar to industrial robots. PID is internally calculated at a 10 millisecond rate. The motor’s PID values are pre-tuned by VEX for excellent performance across all operating conditions.

Advanced users can bypass the internal PID and take direct control with raw, unaltered PWM (pulse-width modulation) control. Raw control still has the same rpm limits, current limits, and voltage maximum that keep the motor’s performance identical.

Additional control of the V5 Smart motor is achieved by internal encoders. These measure the amount of rotation of the shaft socket. The rotation is divided into a number of steps or “ticks” which provides feedback as to the amount a shaft has turned. The resolution of the encoder is determined by the internal gear cartridge of the motor. The encoder values are provided in the chart below per each gear cartridge.

“Consistent motor performance is a game changer”

One of the (11W) V5 Smart Motor’s most unique capabilities is completely consistent performance. The motor runs internally at a slightly lower voltage than the battery’s minimum voltage, and the motor’s power is accurately controlled to +/-1%. This means the motor will perform the same for every match and every autonomous run, regardless of battery charge or motor temperature.

Stall current is limited to 2.5A to keep heat under control without affecting peak power output. Limiting stall current eliminates the need for automatic resetting fuses (PTC devices) in the motor, which can cause unintended motor outages. The 2.5A limit essentially removes the undesirable region of the motor’s performance curve, ensuring users do not unintentionally create stall situations. Finally, to make sure the motor lasts, the internal temperature is monitored. If a motor is approaching an unsafe temperature, the user gets a warning. If the motor reaches its temperature limit, performance is automatically reduced to ensure no damage occurs. The motor has four levels of response to rising temperatures. Each temperature level limits the motor current: level 1 = 50% current, 2 = 25% current, 3 = 12.5% current, 4 = 0% current.

The motor calculates accurate output power, efficiency, and torque, giving the user a true understanding of the motors performance at any time. Position and angle are reported with an accuracy of .02 degrees. All of this data is reported and graphed on the V5 Motor Dashboard. For more information on viewing the V5 Motor Dashboard, view this article from the VEX Library.

The motor's #8-32 Threaded Inserts can be flipped over in the motor’s housing and this will make them flush with the housing rather than slightly protruding. This is useful when the motor will not be mounted directly to a piece of structural metal. For example, this will allow the motor to be mounted using standoffs. Should any damage be caused, there are replacement parts for the motor so an entire motor does not need to be replaced when it is damaged. These include the V5 Smart Motor Cap Replacement and the V5 Smart Motor #8-32 Threaded Inserts.

Lastly, the V5 Smart Motor ports are illuminated with a red LED for visual communication. No red light indicates that no connection is made with a powered V5 Brain. A solid red light indicates a connection is made with a powered V5 Brain and it is communicating. A fast flashing red light indicates which motor is connected to a port that has been selected in the V5 Brain's Device Info Screen. A slow blinking red light indicates there is a communications fault. For more information on using the V5 Smart Motor (11W), view the following articles from the VEX library.

Motor Programming

Advanced Options
  V5 Smart Motor (11W) Specifications Motor 393 + Controller 29
Speed Approximately 100, 200 or 600 rpm 120, 160 or 240 rpm
Peak Power 11 W 3.93 W
Continuous Power 11 W 2.70 W
Stall Torque (with 100 RPM cartridge) 2.1 Nm 1.67 Nm
Low Battery Performance 100% Power Output 51% Power output
Feedback Position
Velocity (calculated)
Torque (calculated)
Efficiency (calculated)
Encoder 1800 ticks/rev with 36:1 gears
900 ticks/rev with 18:1 gears
300 ticks/rev with 6:1 gears
627 ticks/rev with High Torque gears1
392 ticks/rev with High Speed gears1
261 ticks/rev with Turbo gears1
Dimensions 2.26” W x 2.82” L x 1.30” H
57.3 mm W x 71.6 mm L x 33.0 mm H
1.97” W x 2.16” L x 0.98” H
50 mm W x 55 mm L x 25 mm H
Weight 0.342 lbs
155 grams
0.209 lbs
95 grams

1. Motor 393 Position requires the Integrated Motor Encoder (IME).

For more information, help, and tips, check out the many resources at VEX Professional Development Plus

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