17 votes
Accepted

How can I reverse the direction of a brushless motor?

Swapping any two of the wires connecting a brushless DC motor to its ESC will reverse the direction it spins. Despite the name BLDC which implies that the motor runs on DC power, each of the three ...
ifconfig's user avatar
  • 5,998
15 votes

Why do brushless motors have 3 wires compared to 2 wires on a brushed motor?

A standard brushed motor has a positive, negative and a commutator that switches the polarity of the rotor. Conversely, a brushless motor has a multiple of three sets of coils. These coils are ...
Drones and Whatnot's user avatar
14 votes
Accepted

Why does a brushless drone fly longer?

Brushless motors (aka BLDC) are typically[*] more efficient than brushed DC motors. Higher efficiency equates to longer flight times for a same battery pack. Amongst other reasons: The inrush ...
Kenn Sebesta's user avatar
  • 1,912
14 votes
Accepted

What does KV mean on motors?

Ok, so this could turn into a very long answer! The short version is, Kv stands for the velocity constant, and it has to do with the rotational velocity it takes to generate one volt of back EMF. ...
QuadMcFly's user avatar
  • 1,200
13 votes
Accepted

How does one hold the motor bell still when tightening prop nuts?

You know those rubber wristbands that are given out at lots of events? You can wrap one of those around the motor bell to get better purchase on it, and then torque down the prop nut. There are also ...
Drones and Whatnot's user avatar
12 votes

What does BEC, SBEC, UBEC, and OPTO mean for brushless motor ESCs?

BEC: Battery-eliminating circuit. Basically just allows you to use the ESC to power the controls circuit, servos, etc. (hence eliminating the need for a battery) SBEC: Switched battery-eliminating ...
Lee J C's user avatar
  • 121
12 votes
Accepted

Does frequently changing the amount of power to a bldc motor wear it out?

No, changes in speed should have little effect. The only wearing part of a brushless motor is the bearings, which are generally rated for a certain number of rotations and a certain load (and are ...
Robin Bennett's user avatar
11 votes

What does KV mean on motors?

KV, often stylized as kV, is a rating for how quickly the motor will rotate for every volt supplied to it. (units of rpm/volt). However, this is only exactly true ...
ifconfig's user avatar
  • 5,998
10 votes

What happens if i select the wrong number of motor poles in BetaFlight?

This is a setting that is needed for RPM sensing and RPM filtering. An ESC can not sense the RPM of your motors directly, but can sense how often the magnets in the motor bell pass by the coils in its ...
FlashCactus's user avatar
  • 2,997
10 votes
Accepted

What is this ring attached to the bottom of this rotor shaft?

That is a circlip (or C-clip) - it looks like it is used here to prevent the shaft from coming out of the bearing. From the Wikipedia link above: A circlip (a portmanteau of "circle" and &...
Kralc's user avatar
  • 6,036
9 votes
Accepted

Can I run two motors off of one ESC?

Technically, you could connect 2 motors, and it will probably work if they're exactly the same size and model, and have identical props on them. However, if the motor-prop combinations are ...
FlashCactus's user avatar
  • 2,997
9 votes

What do the numbers mean on a brushless DC motor?

A four-digit number (e.g. 2212) This number describes the dimensions of the stator inside the motor. The first two digits are the diameter (in mm) and the second two digits are the height (again, in ...
Kralc's user avatar
  • 6,036
8 votes
Accepted

What does BEC, SBEC, UBEC, and OPTO mean for brushless motor ESCs?

This is an understandably confusing topic because of how the names evolved, and some of those acronyms have become more of a marketing label rather than an actual term. So I'm going to dive a bit ...
FlashCactus's user avatar
  • 2,997
8 votes
Accepted

Why do brushless motors have 3 wires compared to 2 wires on a brushed motor?

TL;DR: Brushed DC motors have two wires because they require DC current (+VCC and Ground), while brushless motors require more complex driving circuitry which controls the AC current required to ...
ifconfig's user avatar
  • 5,998
8 votes

How can I reverse the direction of a brushless motor?

Swap any two of the wires between the ESC and the motor. Alternatively, use the configurator on your computer for whatever firmware your ESC runs and switch the direction via the software. For ...
Drones and Whatnot's user avatar
7 votes

What does BEC, SBEC, UBEC, and OPTO mean for brushless motor ESCs?

A BEC is a Battery Eliminator Circuit. This provides a way for you to power other components, such as servos from a source that is more regulated than VBAT. An SBEC (Switching Battery Eliminator ...
Drones and Whatnot's user avatar
6 votes
Accepted

Effect of motor load on ESC?

The primary thing that high torques affect in a brushless motor is the current flowing through. It obviously affects your ESCs, but also the motors themselves: high currents have been known to melt/...
FlashCactus's user avatar
  • 2,997
6 votes
Accepted

Difference between iFlight XING-E and XING motors?

The Xing and Xing-E motors have two primary differences, materials used in the bell construction, and the magnets used. The bell is a lower stength 6061 aluminum alloy than what they claim for the ...
QuadMcFly's user avatar
  • 1,200
6 votes
Accepted

Does the performance of a brushless motor decrease over time?

Like most things, it depends on how you treat it. As far as I know, you should never need to worry about a brushless motor wearing out, especially for our purposes where we will likely demolish them ...
Drones and Whatnot's user avatar
6 votes

Is there a method to wire a brushless motor to an ESC so it spins in the required direction first time?

Without disassembling the motor, and figuring out how the ESC is designed, there is no other way then simply testing it. From my experience, the motors spinning clockwise has usually been the ones ...
Hannes Hultergård's user avatar
6 votes
Accepted

Brushless Upgrade for RC Car

The important points are: The physical size. One of these is labelled 'BL3650', which probably means that the can is 36mm diameter and 50mm long. Of course, it doesn't have to be exactly the same ...
Robin Bennett's user avatar
5 votes

How does one hold the motor bell still when tightening prop nuts?

You don't need to hold it with a tool, it's enough to pinch it with your fingers. Using a tool to hold it increases the risk of damaging the threads if you are not careful. But I can understand if ...
Hannes Hultergård's user avatar
5 votes

How does one hold the motor bell still when tightening prop nuts?

There are commercially-available tools that are designed to grab around the bell using a rubber band, like this one: However I felt that it's a fair bit too expensive for what it is. So I made my ...
FlashCactus's user avatar
  • 2,997
5 votes

Can I run two motors off of one ESC?

From a technical standpoint it is possible, but there are a number of considerations: Only need one ESC so lighter ESC needs to have a higher current rating to fully power the motors Motors must be ...
Kralc's user avatar
  • 6,036
5 votes
Accepted

Why do brushless drone motors tend to be more expensive than brushed?

Brushless motors are typically CNC machined for a large part of their manufacturing process. The top part of the bell and bearing race are machined from aluminum. The shafts typically steel or a ...
QuadMcFly's user avatar
  • 1,200
5 votes
Accepted

Why do most multirotors use outrunner brushless motors?

The difference between outrunner and inrunner BLDC (brushless DC) motors is that an outrunner's rotor is outside the stator while an inrunner's rotor is inside the stator. (cit.) In general, ...
ifconfig's user avatar
  • 5,998
5 votes
Accepted

How to measure the RPM of a drone motor using Betaflight?

Bi-directional DShot can help you here. After updating the BLHeli firmware on your BLHeli_32 ESCs to the latest version (support was added only recently) and the firmware on your flight controller to ...
ifconfig's user avatar
  • 5,998
5 votes
Accepted

Grinding sound on FPV motor but no apparent damage

It looks like a bad phase to me. Check the resistance of each phase, wire 1 to wire 2, wire 2 to wire 3, and wire 1 to wire 3. If one of those is much higher resistance or shows no continuity, then ...
QuadMcFly's user avatar
  • 1,200
5 votes

How can I increase the lifting power?

Faster motors will definitely give you more thrust. However the relationship isn't linear but increases with the square of the speed. So doubling the kV will give you 4 times the power, and going from ...
Robin Bennett's user avatar
5 votes
Accepted

Lipo battery with an ESC and a BLDC motor

The motor part number (Turnigy L2210C-1200) tells you two things: The 2210 is the physical size and the 1200 is the Kv rating. The Kv rating tells you the RPM (revolutions per minute) per volt applied....
Kevin's user avatar
  • 501

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