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Specialist in Multirotor Tech & FPV Equipment

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DYS XML20A BLHeli Multirotor 3-4S OPTO 20A Slim ESC

DYS XML20A BLHeli Multirotor 3-4S OPTO 20A Slim ESC


Only 1 left in stock

DYS multicopter parts

Messy quad builds, if you ask us, ESCs are the problem. They have 7 wires leading from them, which is a recipe for untidiness. While you can't remove the wires, you can hide them and this ESCs lets you do just that. The XML20A is unique in that it is probably one of the slimmest 20A ESCs on the market. Measuring just 8.5mm wide, it will fit inside tubes as narrow as 10mm. So if your multirotor uses carbon tubes, this is the ESC for you.

The XML20A is one of DYS's new XM series ESCs. The XM series feature the latest in ESC technology. The XML20A in particular features the new Silicon Lab 8051 series processor, which has a running speed of 50MHz, the SN/BL series ran at 16MHz. The extra processing capability makes it particularly suited to high KV motors and helps to delivery an even faster throttle response making it a great choice for racing and acrobatic mini quads. Additionally the drive circuit has been upgraded to ultra-low resistance MOS, which improved the overall efficiency and reliability.

The DYS XM ESCs arrive factory-flashed with BLHeli firmware, supporting OneShot125 and damped mode to give ultra fast throttle response. For those than don’t know, BLHeli is a next generation firmware which looks set to take over from the dominance of SimonK firmware. BLHeli offers great new features like OneShot125* and Damping Light. OneShot125, simply put is a feature that lets your flight controller communicate with your ESCs much faster; the result being your multirotor can respond much quicker to commands. On the other hand Damping Light is a sort of active breaking. With normal ESCs when you reduce the throttle, the motor will only be slowed down passively by the drag of the props. With Damping Light enabled, the ESC will act like an electronic brake to actively reduce the motor speed. Again, this feature makes for a much more responsive and stable multirotor. While OneShot125 and Damping Light are the killer features of BLHeli, there are other benefits. For example, you can configure the ESCs to sound a beacon if they sit idle for 10minutes, which might just help you find your racing quad if you crash it in a field of long grass.

Thankfully the configuration is made easy by the BLHeli software suite, and connecting them to a computer is also straightforward. The DYS XM ESCs support configuration via your flight controller. This means you don't need to remove them from your drone or even use a USB linker (although this is also supported - compatible USB linker). Simply install betaflight (instead of cleanflight) on the FC and download the latest BLHeli suite - more instructions here.

The DYS XM 20amp ESC is avaible in three formats:

  • XM20A V1 - no motor wires, direct solder pads, reduces weight and lends itself to neat installations
  • XM20A V2 - identical to V1, but with soldered motors wires
  • XML20A - super slim, can be installed within a 10mm tube


  • XM sereies upgraded from BL/SN series, new SiLabs 8051 microprocessor
  • BLHeli 14 and OneShot125 ultra high speed preinstalled
  • Includes BLHeli Boootloader - supports ESC programming via FC.
  • Dampened Light (active braking) enabled
  • Super Slim, can be fit inside a 10mm tube
  • Fast throttle response – high 500Hz throttle refresh rate compatible with all flight controllers
  • Supports high KV motors
  • Twisted signal cable reducing the crosstalk during signal transfer
  • New ultra-low resistance MOSFET for superior current handling

NOTE: These ESCs have no BEC, they are OPTO. You will need a 5V BEC to power your flight controller/receiver.​

*Your flight controller must support OneShot to take advantage of this feature.

For more information about BLHeli, please refer to the BLHeliSuite website.

  • Model: XML20A
  • Battery: 12.6-16.8V (3-4S Lipo)
  • Current Rating: 20amp / 22amp burst
  • BEC: No (OPTO)
  • Signal frequency: 20-500Hz / Oneshot125 Ultra high speed (3000Hz)
  • Firmware: BLHeli (bootloader and formware)
  • Size: 48x8.5x4mm
  • Weight: 6.7g


  • 1x DYS XML20A

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What you need to know about ESCs: ESCs or Electronic Speed Controllers act as the messenger between your flight controller and motors. They provide a pulsating signal to the motors to drive a change in RPM and thus a resulting multicopter movement. A good ESC is paramount to stable flying. As brushless motors are multi-phased, normally 3 phases, you can't just apply DC power to turn them on. An ESC is basically a motor controller board that has a battery/signal input and a three phase output for the motor. Each ESC is controlled independently by a PPM signal that ranges from 1ms (min speed=turn off) to 2ms (max speed) in pulse width. The frequency of the signals varies between manufacturers, but for a multirotor it is recommended to use an ESC that supports a high refresh rate. A fast ESC will enable the motors to adjust quickly improving throttle response, drastically increasing stability and providing a more locked in feeling. Some ESC support programming, meaning you can reflash them with custom firmware. For instance, multirotor firmware such as SimonK is highly recommended by many for the best flight performance. However, caution should be applied as it is possible to ruin an ESC when attempting this process, therefore only a competent person with the correct equipment should attempt to reflesh an ESC. If you're after a good tutorial on how to flash your ESCs I recommend reading this.

When choosing an ESC you should match its ampere and voltage rating to your motors and LiPo. Current rating is usually given as 2 figures; a value which represents the maximum continuous current load and a higher burst figure which corresponds to a short term current (allowed normally for no more than 10-30 seconds) e.g. that produced at take off. It's recommend to select a speed controller allowing for a 20% safety margin. The other main ESC rating is the maximum voltage. This is usually expressed as the number of cells, e.g. a 6S LiPo (22.2v).

A lot of ESCs incorporate a BEC (Battery Elimination Circuit). This is a handy feature as it means that (within certain conditions) you do not need a separate receiver battery. They work by stepping down the main battery voltage to usually 5V. However, this process is inefficient and creates heat; the greater the differential between battery voltage and 5V the more heat generated. Consequently BECs (unless of the switching type) only work with a specified number of cells, often only up to a 3S LiPo and also within a specified current load. If not being used, the ESC’s BEC should be disabled by removing the middle (positive) wire to the receiver. For the reasons stated above, most large capacity ESCs do not have a BEC, but instead are almost always of the OPTO type (opto-coupled). OPTO ESCs differ from regular ESCs as the throttle signal between the motor and receiver circuits within the ESC are coupled via a light beam, not by a direct electrical connection. This is supposed to reduce radio interference between the motor and receiver. As a result, OPTO ESC require 5V to power the input side of the optocoupler, this is usually provided from the receiver, which in turn is powered by a separate battery or SBEC.

ESCs have three sets of wiring. On one side two wires, one black and one red that go to the battery or power distribution board. Also on the same side, you would normally have a 3 pin servo/receiver cable that usually plugs into a motor output on your flight controller. Finally the other side commonly has 3 outputs, which connect to the motor cables. If your motor is spinning in the wrong direction, simply swap the positions of two of these wires.

You should also give careful thought to the position of your ESCs within your craft. They are concentrated sources of magnetic interference, so locate them away from flight electronics such as the compass. Make sure they are ventilated, as they are likely to fail if they overheat. Some people recommend placing them out on the frame booms below the motors so that they are cooled by the prop wash; others caution against this approach as they are more vulnerable to damage and longer wires increase the risk of damaging voltage spikes.

Finally, some ESCs come pre-calibrated, however it's advisable to calibrate all ESCs before use by following the manufactures instructions.

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