15

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 energized in a particular order to create a series of electromagnetic forces that ‘pull’ the bell (which contains permanent magnets) around. As there are three sets ...


15

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 wires (connected to one of the three phases in the motor) is driven by the ESC with a phase-shifted AC waveform. Each wire's waveform is shifted by 120 degrees ...


14

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 current at the moment of commutation can involve sparks (which is an inefficient waste of energy), and in any case is a free-running operation without the possibility ...


13

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 specialised tools to hold motor bells, such as the one pictured below which can be found here, on Thingiverse.


13

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. Contrary to a lot of popular belief, it actually isn't a direct measurement of the RPMs at any given input voltage. There is an ancillary relationship between the ...


12

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 reasonably easy to replace). With IC engines there are complex issues piston and bore temperature, expansion, lubrication and heat cycling - but electric motors ...


11

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 circuit. Just an improved version of the BEC which makes it more energy efficient. UBEC: Similar to SBEC, just more energy-efficient at the expense of being ...


11

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 when there is zero load on the motor, thus making the rotation rate with no load applied the so-called "free-speed" of a motor. Adding a load to the motor, such as a propeller, will result in the ...


10

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 stator (this is called eRPM), and will report that number to the flight controller if you've got bidirectional DSHOT enabled. If your motor bell has x magnets (...


10

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 "clip"), also known as a C-clip, Seeger ring, snap ring or Jesus clip, is a type of fastener or retaining ring consisting of a semi-flexible metal ring ...


9

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 mm.) A Kv number (already explained on this site) Kv - or Kv - has some really good answers at the provided link so I won't go into detail here, but it is ...


8

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 drive them. Despite sometimes looking similar on the outside, the functional principles of brushed DC motors and brushless DC motors (aka. BLDC motors) are quite ...


8

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 example, if it is a BLHeli_32 ESC, you can go to the BLHeli_32 Suite and reverse the motor direction from there.


7

Technically, you could connect 2 motors if they're exactly the same and it will probably work. However, there is a good possibility of various weird things happening due to this. The problem with connecting more than one motor to a single ESC stems from how these motors are driven. An electric motor works by using electromagnetic coils to pull permanent ...


7

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 Circuit) and a UBEC (Ultimate Battery Eliminator Circuit) are both versions of BECs that are more efficient. An OPTO is an Opto-coupler, and this isolates the ESC’...


6

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/burn the insulation on motor windings, which then short out and wreck the motor itself and possibly the ESC as well. If the source of this torque is just a prop,...


6

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 deeper into the origins of these names and why the distinction between them exists. The term "BEC", which stands for Battery Elimination Circuit, has its roots in ...


6

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 before they have a chance to wear out. You do have to watch out for the bearings and magnets, however. With the bearings, like any mechanical component, they ...


6

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 that can be wired without crossing any wires and without having to reverse the direction. But that could just be a coincidence, so you should definitely not trust ...


5

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 Xing primary line. Also, even though all motors tend to claim "N52SH" or "N52H" magnets in their specifications, there is a huge range of variation in magnet ...


5

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 you want to use a tool to simplify things, and in that case the other answers are good. Just remember to be careful. Some examples of how I like to hold:


5

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 own, molded specifically for my motors' size: It grabs the motor well (especially thanks to the teeth), but it's quite bulky and motor-specific, so I'm still in ...


5

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 identical (more of a problem if home-building with what's on the bench) Loss of redundancy (if a prop jams or motor fails, you have no thrust) Cannot use ...


5

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, outrunners create more torque and rotate slower than inrunners, which usually have less torque and rotate significantly quicker. The two different designs are ...


5

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 you've got a bad phase. I suspect this is the issue. Also try swapping the motor to a different arm. This will eliminate the ESC as the issue. If the problem ...


5

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 980 to 2450 will give you a bit more than 6 times as much. That's almost certainly too much power for motors (and ESCs) of that size. For double the power, you ...


5

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 size, just fit in the car. Output shaft diameter - so it fits your gear. Mounting bolt pattern, size and spacing. The Kv, or speed constant, which sets how fast ...


4

You can, but it's not recommended. First of, you will need an ESC that can handle twice the current of what one motor consumes. The motors will also be seen as one single motor by the ESC, so of one of them has an error or becomes out of sync, both of them will stop.


4

I feel like it's important enough to mention this to create a new answer even though there's a ton of good information here already, as you mention it's the transient currents that kill ESCs. To be perfectly honest we're well within the rating of even 20A (25A 10 second burst) ESCs in terms of sustained current draw on almost any setup you can imagine. It's ...


4

This table provides guidance to propellor size: ╔══════════════════╦═══════════════╦═════════════════╦══════════════════╗ ║ Frame size ║ Prop size ║ Motor size ║ KV ║ ╠══════════════════╬═══════════════╬═════════════════╬══════════════════╣ ║ 150mm or smaller ║ 3" or smaller ║ 1306 or smaller ║ 3000KV or higher ║ ╠═══════════════...


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