Brushless vs Brushed Motors for Drone: What’s the Difference?

The motor,as the core component of a drone's powertrain,converts the electrical energy stored in the battery into mechanical power to drive the rotation of the propellers.Its performance directly determines the drone's thrust-to-weight ratio,flight speed,flight time,and control stability,making it a critical factor influencing overall flight performance.

Currently,motors used in drones are primarily divided into two main categories:Brushed Motors and Brushless Motors.The key difference lies in the method used to commutate the rotor's current–brushed motors use mechanical carbon brushes and a commutator to switch current direction,while brushless motors rely on an Electronic Speed Controller(ESC)for electronic commutation.

Brushed motors are widely used in entry-level and toy-grade drones due to their simple structure and low cost.However,in fields demanding higher performance and reliability,such as aerial photography,racing,and industrial applications,brushless motors have become almost the standard.

This article will delve into the differences between these two motor types regarding structural principles,performance characteristics,application scenarios,and maintenance costs.It will also provide task-oriented selection advice to help users make scientifically sound decisions based on different budgets and requirements.

I.What is a Drone Brushless Motor?

1.Brushless Motor Working Principle

The working principle of brushless motors differs from that of brushed motors.Instead of using brushes and a commutator,they utilize an Electronic Speed Controller(ESC)to control the direction of the current.The stator of a brushless motor typically consists of windings and an iron core.The ESC,based on the real-time position of the rotor,switches the current flow direction.

This generates a magnetic field that interacts with the permanent magnets on the rotor,thereby driving the rotor to spin.The absence of brushes and a commutator reduces friction losses and brush wear,significantly improving efficiency and lifespan.The electronic control system also enables more precise control of rotational speed and torque,making brushless motors suitable for high-efficiency and high-load application scenarios.

2.Brushless Motor Main Structure

Rotor:

Contains high-performance permanent magnets(e.g.,Neodymium Iron Boron-NdFeB),directly connected to the output shaft,responsible for generating rotational motion.

Stator:

Wound with enameled copper wire.Precise winding arrangements and pole-pair designs influence the motor's speed constant(KV value)and torque output characteristics.

Bearing:

High-speed ball bearings support rotor rotation,reducing friction and enhancing operational stability.

Motor Housing:

Serves as both the structural support and a heat sink.Some models feature cooling holes or integrated fan blade structures.

3.BrushlessMotor Advantages and Disadvantages

Advantages：

High Efficiency:

The brushless structure reduces friction losses.Electrical-to-mechanical energy conversion efficiency can reach 80%~90%,significantly extending flight time.

Long Lifespan:

Absence of brush wear means a theoretical lifespan of thousands of hours.Bearings are the primary wear components.

Strong Power Performance:

Higher power density and torque output for the same size,supporting larger diameter or higher pitch propellers.

Smooth Operation:

Excellent stability,low noise,and low vibration characteristics make them ideal for high-precision tasks requiring stable footage,such as aerial photography and surveying.

Precise Control:

Combined with an ESC,they enable precise RPM control,acceleration curves,and response speed adjustments,meeting the demands of high-speed racing or precision flight.

Strong adaptability:

Brushless motors maintain stable performance in extreme temperature and humidity environments,making them suitable for high-reliability applications such as aviation and military fields.

Disadvantages：

Higher Cost: 

The manufacturing process for brushless motors is complex, and the materials and components used (such as the Electronic Speed Controller, ESC) further increase the overall cost. This cost gap becomes more pronounced, especially in high-performance motors. 

Electromagnetic Interference (EMI):

 The electronic commutation process may generate high-frequency electromagnetic noise, which can interfere with nearby precision electronic equipment (e.g., medical instruments or communication systems). Additional shielding design is required to mitigate this issue. 

4.Brushless Motor Common Types

Outrunner Brushless Motor:

Rotor is located externally,rotating with the outer shell.Magnets are farther from the rotation center,generating higher torque and lower RPM.Suitable for multirotors,aerial photography,and long-endurance flights.

Inrunner Brushless Motor:

Rotor is located internally.Features very high RPM and lower torque,often requiring a gear reduction system.Suitable for FPV racing,fixed-wing,or high-speed drones.

II.What is a Drone Brushed Motor?

1.Brushed Motor Working Principle

Brushed motors achieve current commutation through brushes and a commutator to drive the rotor's rotation.Their working principle primarily relies on the interaction between the magnetic field generated by the stator and the windings carrying current within the rotor.When current flows through the rotor's windings,it interacts with the stator's magnetic field,generating torque that causes the rotor to start rotating.

The rotation of the rotor turns the commutator,which is connected to the motor's power supply via the brushes.The commutator periodically reverses the direction of the current,enabling continuous rotation of the rotor.Due to the friction between the brushes and the commutator,wear and heat are generated.This results in lower efficiency for brushed motors and necessitates regular maintenance and brush replacement.

2.Brushed Motor Main Structure Components

Rotor:

Wound with copper wire coils,connected to the commutator.Generates torque when energized by interacting with the stator's magnetic field.

Stator:

Provides the magnetic field,designed with either permanent magnets or electromagnets.

Commutator:

Mounted on the rotor shaft,composed of segmented copper bars,responsible for switching current direction as it contacts the brushes.

Brush(es):

Made of graphite or metal composite material.Pressed against the commutator surface via springs to enable current flow and commutation.

Bearing:

Supports rotor rotation.Commonly uses sintered bushings(oil-retaining bearings)or ball bearings.

3.Brushed Motor Advantages and Disadvantages

Advantages:

Simple Structure:No Electronic Speed Controller(ESC)required;runs directly from power input.

Low Cost:Mature manufacturing process;material and production costs are far lower than brushless motors.

Easy Control:Speed can be controlled via simple voltage adjustment,making it easy for beginner applications.

Disadvantages:

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Short Lifespan:Brushes and commutator wear out quickly.Lifespan is typically tens to hundreds of hours,requiring periodic replacement.

Low Efficiency:Reliance on mechanical brushes and commutator for current switching results in significant friction losses.Energy conversion efficiency is low,typically only 50%~70%.

Heat and Noise:Friction causes noticeable heat generation and higher operating noise.

Frequent Maintenance:Requires periodic cleaning of the commutator and replacement of brushes.

Prone to electrical noise:Friction between carbon brushes and the commutator generates not only mechanical noise but also electrical noise,which can interfere with other sensitive equipment,particularly in precision applications where its impact is significant.

III.Differences Between Drone Brushless and Brushed Motors

The fundamental difference between Brushless Motors and Brushed Motors stems from their commutation method–the former uses electronic commutation,while the latter relies on mechanical carbon brushes.This difference not only affects structural design but also determines their performance divergence in efficiency,lifespan,control precision,and maintenance costs.

1.Commutation Method&Structural Differences

Brushless:

The ESC sequentially energizes the stator coils to create a rotating magnetic field that drives the rotor.Minimal mechanical wear points due to the absence of brushes and a commutator;structure is more compact and efficient.

Brushed:

Relies on physical contact between brushes and commutator to switch current direction.Friction is inevitable,leading to wear,sparking,and energy loss.

2.Efficiency&Energy Consumption

Brushless:

Electrical conversion efficiency is typically 80%~90%.Low heat dissipation and small heat generation make them suitable for prolonged continuous operation.

Brushed:

Efficiency is mostly 50%~70%.Some energy is consumed by friction and heat.Prolonged operation easily leads to overheating and reduced performance.

3.Lifespan&Reliability

Brushless:

Almost maintenance-free.Theoretical lifespan reaches thousands of hours.Only bearings need periodic checking.

Brushed:

Brush life is limited(tens to hundreds of hours),and the commutator surface gradually wears down,requiring periodic maintenance or replacement.

4.Noise&Vibration

Brushless:

Operate smoothly and quietly with minimal vibration,ideal for scenarios with extremely high stability requirements like aerial photography and surveying.

Brushed:

Exhibit noticeable friction noise during high-speed operation and can cause Electromagnetic Interference(EMI),potentially affecting the stability of some electronic equipment.

5.Power Density&Performance Potential

Brushless:

High power output per unit weight.Can provide greater thrust in a smaller volume,adapting to large-diameter propellers and high-payload tasks.

Brushed:

Lower power density.Suitable for light-load,low-speed,or disposable equipment.

6.Control Precision&Response Speed

Brushless:Paired with an ESC,they enable precise RPM control,fast acceleration/deceleration,and dynamic response,making them ideal for FPV racing or delicate maneuvers.

Brushed:

RPM adjustment precision is limited.Response speed is constrained by mechanical commutation,making it difficult to meet the dynamic demands of high-speed flight.

IV.Application Scenarios for Drone Brushless and Brushed Motors

The choice of motor for a drone isn't simply"one good,one bad";it's the result of mission requirements,performance demands,and budget constraints.Different motor types have their own advantages in different scenarios.Overall:

Brushless Motors:

Offer superior performance,longer lifespan,and lower maintenance,suitable for high-frequency,long-life,performance-sensitive tasks.

Brushed Motors:

Low cost and simple structure,suitable for low-budget,short-life,low-performance-demand applications.

1.Brushless Motor Applicable Scenarios

Professional Aerial Photography&Cinematography:

Requirement:Low vibration,stable thrust,long flight time.

Reason:Smooth,quiet operation of brushless motors,combined with large-diameter,low-RPM propellers,significantly reduces image jitter.

Typical Models:DJI Mavic,Phantom series.

FPV Racing&Acrobatic Flight:

Requirement:Instant acceleration,extreme responsiveness,high RPM tolerance.

Reason:High torque and fast response of brushless motors allow reaching high RPM very quickly.

Industrial&Commercial Missions:

Requirement:Long-duration continuous operation,high reliability.

Reason:Maintenance-free,highly durable,adaptable to harsh environments.

Typical Tasks:Inspection,surveying,pesticide spraying,material delivery.

Long-Endurance Fixed-Wing&VTOL Aircraft:

Requirement:High efficiency,low power consumption,long-duration stable output.

Reason:Brushless motors maintain high efficiency under low loads,extending flight distance and time.

2.Brushed Motor Applicable Scenarios

Toy-Grade&Entry-Level Drones:

Requirement:Low cost,easy replacement,short flight time.

Reason:Low price and simple structure make brushed motors suitable for beginners experiencing flight.

Typical Models:Indoor mini quadcopters.

Education&School Experiments:

Requirement:Intuitive structure,easy maintenance.

Reason:Brushed motors facilitate observing mechanical commutation principles and are easier to disassemble/reassemble.

Short-Term or Disposable Missions:

Requirement:Short usage cycle,no long lifespan requirement.

Reason:High economic efficiency,reducing overall equipment cost.

V.How to Choose Between Brushed and Brushless Motors?

The motor type determines a drone's power performance,operational lifespan,maintenance needs,and overall cost structure.

When choosing,one should not simply pursue"highest performance"or"lowest price."Instead,a comprehensive judgment should be made by combining factors such as mission objectives,budget constraints,usage frequency,and environmental requirements.

1.Mission Requirements&Performance Demands

High-Performance,Mission-Critical Flights:

E.g.,professional aerial photography,FPV racing,inspection/surveying.Require stable thrust,rapid response,smooth operation.

Recommendation:Choose brushless motors.Paired with a suitable KV value and propeller,they enable precise control and high-efficiency output.

Low-Performance,Experiential Flying:

E.g.,entry-level recreational flying,teaching demonstrations.Power demands are low.

Recommendation:Brushed motors are sufficient,economical,and easy to replace.

2.Budget&Total Cost of Ownership(TCO)

Adequate Budget:

Brushless motors have a higher unit price,but their long lifespan and low maintenance costs result in a lower long-term average investment.

Suitable for high-value drone projects or those with long mission cycles.

Limited Budget:

Brushed motors have a low initial investment,suitable for one-off or short-term projects.Even their shorter lifespan won't significantly increase overall costs.

3.Usage Frequency&Lifespan Expectation

High-Frequency Operation:

E.g.,daily aerial photography operations,industrial inspections.Require equipment to work stably for long periods.

Brushless motors'lifespan of thousands of hours avoids frequent replacements and offers high reliability.

Low Frequency or Occasional Use:

E.g.,lab classes,hobby flying(used a few times per month).

The tens to hundreds of hours lifespan of brushed motors is sufficient,and their cost is low.

4.Maintenance&Replacement Capability

Limited Maintenance Conditions:

When operating in remote,harsh,or areas lacking repair facilities,brushless motors are advantageous.Their near-maintenance-free nature reduces failure risk.

Convenient Maintenance:

In labs,schools,or home settings,brush replacement and routine upkeep for brushed motors can be easily performed.

5.Environment&Working Conditions

Harsh Environments:

Under high temperature,dust,or humidity,brush and commutator wear in brushed motors accelerates,significantly shortening lifespan.Brushless motors,with better sealing,offer stronger durability.

Controlled Environments:

In indoor,dry,low-dust environments,brushed motors can also operate stably for extended periods and are more economical.

VI.Common Misconceptions about Drone Brushless and Brushed Motors

Discussions about brushless vs.brushed motors in the drone field never cease.As technology advances,many early-formed notions are no longer valid,leading to several widespread misconceptions.Clarifying these helps in making more scientific choices regarding drone selection and use.

Misconception 1:Brushless Motors are"Maintenance-Free"

Fact:

While brushless motors greatly extend lifespan and reduce maintenance needs due to the absence of brush wear,they are not entirely maintenance-free.Brushless motors still contain mechanical components like bearings,which will wear over time or under heavy use.

Bearings are Key:

Motor bearings are the primary consumable part.Flying in harsh environments(sand,dust,moisture)can introduce contaminants causing rust or wear,leading to noise,vibration,or even motor seizure.

Regular Cleaning is Important:

Periodically using compressed air or a soft brush to remove dust and debris from the motor exterior is crucial for maintaining good cooling and operational condition.

Dynamic Balance Check:

After a severe crash,the motor housing or shaft may deform,disrupting dynamic balance.This causes high-frequency vibration during flight,affecting flight controller stability and image quality.

Therefore,it's more accurate to view brushless motors as"low-maintenance"rather than"maintenance-free."

Misconception 2:Brushed Motors are Obsolete

Fact:

Despite being comprehensively outperformed by brushless motors,brushed motors still hold irreplaceable advantages in specific niches due to their extremely low cost and simple drive requirements.

Toys&Entry-Level Drones:

For price-sensitive markets,brushed motors and simple drive circuits are optimal for cost control.

Micro Indoor FPV Drones(Tiny Whoop):

On gram-scale micro drones,brushed motors provide sufficient power for indoor flight while fully leveraging their lightweight and low-cost advantages.

Education&Experimentation:

Their intuitive structure makes brushed motors excellent for teaching demonstrations,helping beginners understand motor principles.

Brushed motors are not obsolete;they continue to function effectively within their specific niche.

Misconception 3:Brushless Motors are Always More Expensive

Fact:

Comparing only the initial purchase price is deceptive.Evaluating the Total Cost of Ownership(TCO)is more meaningful.

Huge Lifespan Difference:

Brushed motor lifespan is typically tens to hundreds of hours.Performance degrades rapidly as brushes wear,requiring frequent replacement.Brushless motors have a theoretical lifespan of thousands or even tens of thousands of hours,usually limited by bearing durability.

Maintenance Costs:

Brushed motors require periodic maintenance and parts replacement,adding time and component costs.Brushless motor maintenance workload and cost are much lower.

Efficiency&Battery Costs:

Brushless motors are more efficient,converting more electrical energy into power instead of heat.This means longer flight times per charge and fewer battery charge cycles,indirectly saving battery costs.

Misconception 4:Outrunner Brushless Motors are More Advanced than Inrunners

Fact:

There is no inherent"advanced"or"backward"distinction.They are two mature technical routes designed for different applications.

Different Characteristics,Different Uses:

Outrunner motors feature high torque and relatively low RPM.They can drive propellers directly without a gearbox,offering simple structure and high reliability–ideal for multirotor drones.

Inrunner Speed Advantage:

Inrunner rotors spin internally at very high RPM but with lower torque.This makes them perfect for applications needing extreme speed,such as Electric Ducted Fan(EDF)jet models or high-speed fixed-wing drones using reduction gearboxes.

Market Dictates Visibility:

Outrunner motors dominate the consumer and professional multirotor drone market,creating a perception of being more"common"or"advanced."This is merely a difference in application domain,not a generational gap in technology.

VII.Frequently Asked Questions(FAQ)

Q1:What do the numbers in brushless motor model names(e.g.,2207,2810)mean?

These numbers typically describe the dimensions of the motor stator,a key parameter determining performance.

The first two digits(e.g.,22)represent the stator diameter(in millimeters).

The last two digits(e.g.,07)represent the stator height(in millimeters).

Generally,a larger stator size means higher motor torque and power,but also increased weight and power consumption.

Q2:What are common failures in brushless motors?

Abnormal Noise or Rough Rotation:Usually caused by damaged bearings or debris inside the motor.

Motor Shaking or Phase Loss:Motor spins weakly with severe shaking.Often due to a poor connection in one of the three motor wires to the ESC,or damaged internal windings.

Reduced Magnetism:Prolonged operation at excessively high temperatures can demagnetize permanent magnets,reducing motor efficiency and power.

Q3:How do dust,moisture,or high temperatures affect brushless motors?

Dust and Sand:Accelerate bearing wear and can potentially jam the motor.Clean promptly with compressed air after flying in dusty/sandy conditions.

Moisture:While motors have insulating varnish,moisture can still cause bearing rust or short circuits at coil terminals.Dry the motor thoroughly immediately after flights involving water or rain.

High Temperatures:The nemesis of brushless motors.Overheating reduces magnet performance(demagnetization),accelerates bearing aging,and can even burn out windings.

Q4:Why are some brushless motors expensive while others are cheap?

Price differences mainly reflect materials,craftsmanship,and design:

Materials:High-end motors use higher-grade magnets(e.g.,N52SH),high-temperature resistant wire,and better quality bearings.

Craftsmanship:Expensive motors have superior dynamic balancing(minimal vibration),neater winding with higher slot fill rates(improving efficiency),and tighter manufacturing tolerances/precise assembly.

Design:High-end motors invest more in thermal management(e.g.,vented housings,integrated fan blades)and lightweighting,ensuring performance while minimizing weight.

Q5:What is the relationship between a brushless motor's KV value and thrust output?

The KV value(RPM per Volt)is a crucial parameter indicating the motor's rotational speed per volt of input(RPM/V).A higher KV value means the motor spins faster at a given voltage,but typically produces lower thrust and torque.It's suitable for high-speed flight or racing.A lower KV value generally provides higher thrust,making it suitable for large-diameter propellers and long-endurance flight applications.