DYS BL20A / SN20A Mini Opto ESC – Alternative to KISS ESC

by Oscar

KISS 18A ESC has been one of the most popular ESCs, they are light weight (2g excluding cables) and perform exceptionally well thanks to the higher signal update rates. However I have not personally tried KISS ESC, due to their high price point and frequent incidences of catching fire.

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Finally DYS has released a similar size/weight ESC that is much cheaper (at $11), yet able to run BLHeli firmware and have oneshot / damping light supported.

This ESC is tiny compared to other regular 20A ESCs.



  • Current: 20A
  • Peak Current: 22A
  • PWM output rate: 18KHz
  • Signal refersh rate: 20-500Hz
  • Outout PWM frequency: 18KHz
  • App program: SimonK
  • Battery: 2-4S
  • BEC: NO
  • Battery: 2 – 4S
  • Size: 23*12*4.5mm
  • Weight: 7.6g(with wires) 2g (without wires)

Be aware that this ESC has no BEC (one of the reason why they can be made so small and light), which means you will need additional 5V power source for your Radio receiver and flight controller. I recommend using one of your spare normal ESC if you want to save some money. :)

There are two series of ESCs, one is branded as SN20A which has SimonK flashed. The BL20A has BLHeli fimrware, so make sure you know which you are you buying.


Actually the DYS BL20A mini ESC was release late February / early March. But now more and more resellers are carrying them in the shops, making it more widely available. Here is a link to the DYS BL20A Mini ESC product page on Banggood, I like them because they offer free shipping world wide (you can also pay a little extra get it within a week).

RCTimer has a similar 20A mini ESC, from the layout of the component and PCB, it looks identical to the DYS BL20A ESC. I believe RCTimer just rebranded them.

DYS SN20A compared to a coin.

dys-sn20a-bl20a-mini-esc-pcb-compoent dys-sn20a-bl20a-mini-esc-pcb-compoent-size-compare-coin

The RCTimer 20A Mini ESC.


Manual, instruction from DYS SN20A ESC.


Update (15 Jul 2015) – ESC on Fire

There have been lots of report of these SN20A ESC catching fire. Some say it’s a particular batch that caused issue. Anyway I did also experienced some quality control issues with these ESCs as well. 2 out of 8 were faulty from my order. Here are some pictures of the burnt ESC from our Multicopter group.

dys-sn20a-esc-burnt-fire-blow-up-quadcopter dys-sn20a-esc-burnt-fire-blow-up-mini-quad dys-sn20a-esc-burnt-fire-blow-up

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Rob 5th November 2019 - 9:20 am

Using those ESC’s since 2015 (four years now) never had a slightest issue with.
Really good cheap stuff.

RCfun 14th December 2017 - 5:46 am

Hi Oscar,
Could I ask whether DYS BL20A / SN20A Mini Opto ESC can be used on RC Plane with 1806 motor, 2300KV, 2S Lipo?
Thank you.

Dave S. 13th December 2015 - 6:34 pm

Hi Oscar.
I have an update on my DYS SN30A opto. I could use a little help myself now.
Even though bending the board for diagnostic reasons can get the motor spinning again there is a pattern evolving.
It seems that the ESC fails several flights after a crash involving that particular motor/prop.
Mine got caught in a net this time and I didn’t realize it immediately so the throttle was not immediately cut.
I have SunnySky X2207s which I believe can demand a lot of amps. I suspect that during a stall the amps drawn exceed the
SN30A maximum capacity. A couple of flights afterwards and I found the motor struggling to start. When that happens and it does eventually start, don’t fly it unless you want to risk motor or a crash.
So what do I do? Get 40 amp esc’s or less demanding motors? I find the 7 minute 2.2 AH battery life a bit annoying too.
Should I replace motor / esc combo entirely? I don’t wan’t to replace esc’s each time I have this kind of crash.
In conclusion, IS there a mounting stress issue AND over current (2 different causes of failure) or just over current. Nothing is obviously Fried at this point so I really don’t know now.

Oscar 14th December 2015 - 5:21 pm

maybe try littlebee 20A, they seem to be tougher than the DyS 20A i found.

Dave S. 7th December 2015 - 12:34 am

Hi Oscar.
I have discovered the cause of my DYS SN30A failures with MY install. Perhaps the info will prove valuable to some.
Everyone usually lashes them on with ty-wraps. Even semi-gently is too much.
Two out of four failed and with a LOT of time I believe the stresses that are created damage the VIA’s inside the board.
Flexing the board one way then the other will cause it to fail and recover. If however the throttle is up when the fault occurs it causes a chip or two to fry. Initial cause-Board stress, symptoms usually a fried chip (the process stalls and all of the current lingers on the chip too long).

Xyphon 15th October 2015 - 10:04 pm

Hi Oscar,
got an issue with those escs. First I had a problem with one, the motor was shaking and emitting a shrill sound. Then I tried to flash them all with the latest version of BLHeli (14.01) but now all four motors have the same problem !
I tried to change the Demag Compensation to High and also the PWM Frequency/Damped to Low, but nothing to do, all four motors are shaky and shrilly sounding :/
Got any idea of what woul be the cause of my problem ?

Gaston Barouille 8th December 2015 - 5:52 pm

Hi Xyphon, I have the same problem with 4 motors. When I check them connected directly to radio RX they work fine , but when I plug on CC3D they do hi freq noise and didn’t work. Sometimes motor #4 works at certain throttle position.
Do some one knows what it could be?

Julian 13th October 2015 - 11:12 am

Hi guys , yesterday i bought 8 esc maytech mini opto KS20A with KISS firmware , but i want help to change reverse rotation motor and parameter (if possible)
i ask Agnes of maytech on skype but no answer now

i don’t found software to setup the ESC

it seems to work fine , very agressiv power up , and very good brake
i build a ZMR modified with cobra 2204- 2300kv , NEURON controler (build in my town , METZ in France)
thanks for help

Oscar 14th October 2015 - 9:42 am

I don’t know those ESC, but easiest way to change motor rotation is to swap 2 of the ESC-motor wires.

DuDlik 3rd October 2015 - 9:18 pm


For what 6 dot on esc plate?

Oscar 6th October 2015 - 4:29 pm

yes that’s right! i think it’s for those who doesn’t have the flashing tools.

Kenny 23rd September 2015 - 7:59 pm

Hi Oscar

I pass my summer toasting those ESC and get may motors toast too

Most of the problem was when I crash and motors still try to run, on a failsafe or bad throttle handle and the prop is stock in the grass. Fix the problem with a proper failsafe and motor stop on cleanflight.

Still, even with this setup, one just fail in air at full throttle when doing a fast climbing. Almost lost my gopro and many craft dommage…

trash that shit and use some new afro 20A race edition, almost as small and you can’t go wrong when the hardware is designed by timecop… never had a problem since that time

xypher 20th September 2015 - 5:51 pm

Hi Oscar

Were you able to get replacement/refund for the faulty esc? I got 3 out of 8 that do not work. Terrible.

Oscar 21st September 2015 - 4:02 pm

Banggood did send me a couple replacement after reporting, but that took a while for them to reply and ship…

willy 16th September 2015 - 10:49 pm

After a lot of search to see what was the best deal I bought 4 of this DYS SN20A, I flashed with BLHeli 14.0 and configured on my CC3D, after some tests on air everything run ok and smooth, than next day when i was doing some PID setup over the table after 3sec of full throttler without props one ESC burn, no idea what was that … i got a new one from warranty but the seller send the BL20A version.. he told me that i could flash it with the same hex as i did on others but i coudnt find the BL20A firmware version, so i flashed with de SN20A firmware version… now the motor act like shaking… the question is, did the esc burned the motor too when it burned or is because i flash with SN20A firmware version and not BL20A firmware version that i cant find?

Greg 19th September 2015 - 9:33 am

Hi Willy,

sorry I can’t help you, but I’m facing same problem. One ESC burned, then I replaced it by a new one, and motor is shaking. Sometimes I can fly few minutes, then one motor or many I don’t know, stopped spinning and it fall down.
Those ESC are installed between 2 carbon plates, I think it could be a problem. I just buy a new one and will try again with a better isolation and I will tell you.

Alexandru 10th August 2015 - 7:42 pm

Hi Oscar,
I’ve ordered these ESCs and re-flashed them to BLHeli from the beginning I’ve got them. Not sure if this is firmware issue (or I have to re-flash them again) but once it takes off, flies about 3-5 seconds and fells down. Looks like one of the rear motors stops working (suddenly). Then I hear the initialization beeps from the motor. Is not the power issue as all LEDs are on and if I push throttle, motors spines up (just few of them). Sometimes I here motors beeping and beeping (till I disconnect the battery), but don’t understand which one re-initializes.
Also is not the motherboard the issue as the quad is still active and responsive to tx. Or maybe motherboard has to be re-flashed?…

Oscar 12th August 2015 - 4:08 pm

sounds like bad ESC… have you tried the latest BLHeli firmware? 14.0?

Airyck 16th December 2015 - 5:22 am

Hi Alexandru,

Also make sure to go through the ESC calibration process again if you haven’t already (I know this is an older post but it might help someone else). You can do this in Cleanflight/Baseflight by connecting and going to the “motors” page. *REMOVE YOUR PROPS FIRST*- Enable the motor sliders and push the master slider all the way up; plug in your battery at this point; you’ll hear some musical tones. When the musical tones finish move the master slider all the way down; when the musical tones stop the calibration is complete and you can disable the motor sliders again.

klaatu 6th July 2015 - 10:56 pm

lotta complaints about these escs on banggood’s reviews, saying 1 wire bootloader doesnt work or that they donk work at all or blow up when connected to battery

Oscar 7th July 2015 - 5:05 pm

me and a friend both successfully flash these ESC via one wire, no problems at all! “lotta complaints” you mean 3 people? LOL I am sure there are a lot more for the KISS ESC…

klaatu 7th July 2015 - 7:41 pm

3 out of 6 reviews is HALF the people complaining….other half is complaining about other stuff…im not saying they not good but im not really comfortable with these reviews

Chris Barth 26th June 2015 - 11:48 pm

BEC or no BEC these ESC’s are super small and surprisingly tough. I regularly pull 25+ amps at 4s through these without them breaking a sweat. I use the simonk bootloader with blheli firmware so I can use my afro usb tool. These perform better than some ESC’s costing twice as much.

Mpkiteman 27th May 2015 - 10:29 am

Hi Oscar, have a look at this, they are already with Blheli ;-)


It’s the same product than DYS, but branded RCX !

hendrikw 18th May 2015 - 10:42 pm

Hi Oscar,
Did you get the BLHeli or the Simonk version?
I know I can flash BLHeli on the Simonk version using my afro usb programmer but would this work the same for the BLHeli? Would I be able to flash Simonk to the BLHeli version?

Oscar 20th May 2015 - 10:22 am

i haven’t placed my order yet, but i am planning to get the BLheli version :)
to your question, only if the ESC’s got SimonK bootloader otherwise you need need a AVR programmer and flash directly to the chip.

Adam 14th May 2015 - 4:26 am

I’ve flown two identical quads, one with KISS esc’s, one with these DYS SN20a’s flashed with BL heli, both with active braking and oneshot enabled, both running the same PID’s. In my opinion, the DYS one flew alot nice, had crisper responses to throttle changes, and just felt more locked-in overall. I’d defiantly rather buy four DYS esc’s for the price of one KISS esc, because from my experiece, they’re alot better, and less prone to fires

Oscar 18th May 2015 - 2:55 pm

interesting ! thanks for the info :)

rahul joshi 13th May 2015 - 1:32 pm

Sir,if we want to use pid controller to control speed of bldc,how can it work and can bldc work without esc.?

Chris Barth 27th June 2015 - 12:14 am

ESC’s are controlled by PWM input from some signal source. Its hard to beat a ESC for driving these BLDC motors they are pretty amazing for what they do. The microprocessor takes the PWM signal input and electronically commutates the motor through the FET’s which split up the DC power input into three separate channels or phases. Motor position and rotation is sensed by the unpowered phases back EMF.

thomas 10th May 2015 - 4:54 pm

I think i know what esc´s im gonna take.
I´ll soon order all parts for my first mini, so excited.

Artur Banach 9th May 2015 - 6:49 pm

I should have them next week:)