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How to calculate the power of a brushed DC geared motor?

Mar 09, 2026

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When it comes to the world of motion and mechanical power, brushed DC geared motors stand as reliable workhorses. As a seasoned supplier of brushed DC geared motors, I've seen firsthand how these motors power a wide range of applications, from small DIY projects to large industrial machinery. Understanding how to calculate the power of a brushed DC geared motor is crucial for selecting the right motor for your specific needs and ensuring optimal performance. In this blog post, I'll guide you through the process of calculating the power of a brushed DC geared motor, step by step.

Understanding the Basics of Brushed DC Geared Motors

Before we dive into the power calculation, let's briefly review the basic components and operation of a brushed DC geared motor. A brushed DC motor consists of a stator (the stationary part) and a rotor (the rotating part). The stator contains permanent magnets, while the rotor has coils of wire that carry an electric current. When an electric current is applied to the rotor coils, a magnetic field is created, which interacts with the magnetic field of the stator, causing the rotor to rotate.

The gearbox in a brushed DC geared motor is connected to the motor shaft. It consists of a series of gears that reduce the speed of the motor and increase the torque. This makes the motor more suitable for applications that require high torque at low speeds, such as robotics, automation, and automotive systems.

Key Parameters for Power Calculation

To calculate the power of a brushed DC geared motor, we need to consider several key parameters:

  1. Voltage (V): The voltage applied to the motor is measured in volts (V). It determines the electrical potential difference across the motor terminals and affects the motor's speed and torque.
  2. Current (I): The current flowing through the motor is measured in amperes (A). It represents the amount of electrical charge passing through the motor per unit of time and is related to the motor's power consumption.
  3. Speed (N): The speed of the motor is measured in revolutions per minute (RPM). It indicates how fast the motor shaft rotates.
  4. Torque (T): The torque of the motor is measured in newton-meters (N·m). It represents the rotational force produced by the motor and is crucial for applications that require the motor to perform work, such as lifting, pulling, or rotating objects.

Calculating the Electrical Power of the Motor

The electrical power consumed by the motor can be calculated using the formula:

[ P_{elec} = V \times I ]

where ( P_{elec} ) is the electrical power in watts (W), ( V ) is the voltage in volts (V), and ( I ) is the current in amperes (A).

For example, if a brushed DC geared motor is operated at a voltage of 12 V and draws a current of 2 A, the electrical power consumed by the motor is:

[ P_{elec} = 12 \text{ V} \times 2 \text{ A} = 24 \text{ W} ]

Calculating the Mechanical Power of the Motor

The mechanical power output of the motor can be calculated using the formula:

[ P_{mech} = \frac{2 \pi N T}{60} ]

where ( P_{mech} ) is the mechanical power in watts (W), ( N ) is the speed in RPM, ( T ) is the torque in N·m, and ( \pi ) is a mathematical constant approximately equal to 3.14159.

For example, if a brushed DC geared motor operates at a speed of 1000 RPM and produces a torque of 0.1 N·m, the mechanical power output of the motor is:

[ P_{mech} = \frac{2 \times 3.14159 \times 1000 \text{ RPM} \times 0.1 \text{ N·m}}{60} \approx 10.47 \text{ W} ]

Efficiency of the Motor

The efficiency (( \eta )) of a motor is defined as the ratio of the mechanical power output to the electrical power input:

[ \eta = \frac{P_{mech}}{P_{elec}} \times 100% ]

Using the values from the previous examples, the efficiency of the motor is:

[ \eta = \frac{10.47 \text{ W}}{24 \text{ W}} \times 100% \approx 43.62% ]

DC Geared Motor 12V12mm Mini Gearbox Motor

A higher efficiency indicates that the motor converts a larger proportion of the electrical energy it consumes into mechanical energy, which is desirable for applications where energy conservation is important.

Factors Affecting the Power of a Brushed DC Geared Motor

Several factors can affect the power of a brushed DC geared motor, including:

  1. Load: The power required by the motor depends on the load it is driving. A heavier load requires more torque, which in turn increases the power consumption of the motor.
  2. Speed: The power output of the motor is directly proportional to its speed. As the speed increases, the power output also increases, provided that the torque remains constant.
  3. Voltage: The voltage applied to the motor affects its speed and torque. A higher voltage generally results in a higher speed and torque, which increases the power output of the motor.
  4. Temperature: The temperature of the motor can affect its performance and power consumption. As the temperature increases, the resistance of the motor windings also increases, which reduces the current flowing through the motor and decreases its power output.
  5. Gearbox Efficiency: The efficiency of the gearbox can also affect the overall power output of the motor. A more efficient gearbox will transfer more of the motor's power to the output shaft, resulting in a higher power output.

Applications of Brushed DC Geared Motors

Brushed DC geared motors are widely used in a variety of applications, including:

  • Robotics: They provide the necessary torque and speed for robotic joints and actuators, allowing robots to perform tasks such as lifting, gripping, and moving.
  • Automation: These motors are used in conveyor belts, sorting systems, and other automated machinery to control the movement and position of objects.
  • Automotive: Brushed DC geared motors are used in automotive applications such as power windows, windshield wipers, and seat adjusters.
  • Consumer Electronics: They are found in a variety of consumer electronics products, such as toys, cameras, and portable fans.
  • Medical Devices: These motors are used in medical devices such as infusion pumps, respirators, and surgical instruments.

Selecting the Right Brushed DC Geared Motor for Your Application

When selecting a brushed DC geared motor for your application, it's important to consider the following factors:

  1. Power Requirements: Calculate the power requirements of your application based on the load, speed, and torque requirements. Choose a motor that can provide the necessary power output.
  2. Voltage and Current Ratings: Ensure that the motor's voltage and current ratings are compatible with your power supply.
  3. Speed and Torque Characteristics: Consider the speed and torque characteristics of the motor to ensure that it can meet the requirements of your application.
  4. Gearbox Ratio: Select the appropriate gearbox ratio to achieve the desired speed and torque output.
  5. Size and Weight: Consider the size and weight of the motor and gearbox to ensure that they can fit into your application.
  6. Efficiency: Choose a motor with a high efficiency to reduce power consumption and operating costs.

Our Range of Brushed DC Geared Motors

At our company, we offer a wide range of high-quality brushed DC geared motors to meet the diverse needs of our customers. Our motors are designed and manufactured to provide reliable performance, high efficiency, and long service life.

Contact Us for Your Brushed DC Geared Motor Needs

If you're in the market for a high-quality brushed DC geared motor, we'd love to hear from you. Our team of experts can help you select the right motor for your application and provide you with the technical support you need. Contact us today to discuss your requirements and get started on your next project.

References

  1. Electric Motors and Drives: Fundamentals, Types and Applications, Fourth Edition. Austin Hughes, Bill Drury.
  2. Mechatronics: An Integrated Approach. Clarence W. de Silva.
  3. Principles of Electric Machines and Power Electronics. P. C. Sen.