KISS 24A ESC Race Edition – Review, Setup, Guide

Flyduino kindly sent us a set of the new KISS 24A ESC Race Edition (RE) to try out. In this post we will go through the key features, performance testing, and finally some guides on how to use these KISS 24A ESC.

Get your KISS 24A ESC Race Edition from Flyduino.

Also Check out my review on the KISS FC.

Overview of KISS 24A ESC Race Edition

In this review I will talk about the following topics, hopefully it will cover most of the stuff that a new user would normally ask.

  1. Features and Spec
  2. Hardware
  3. Firmware
  4. Telemetry
  5. Why ESC Catch Fire – Over-Current/Temperature Protection
  6. How to use KISS 24A ESC RE
    • Connection to FC and Motor
    • Reverse Rotation
    • Calibrate ESC
    • Flash Firmware
    • Running 5S / 6S / 3D mode
  7. Performance Testing
  8. Conclusion

Last Update: 28/02/2016

Many thanks to Artur Banach for taking some of the pictures for me! :)

Features and Specification

kiss 24A esc re fpv mini quad

Here is a list of features from the product page. I added my own comment in green text.

  • 32-bit processor
  • Allows 24A continuous current even with bad ESC cooling – I think they mean even mounting ESC’s inside the frame and not the arms, e.g. using their carrier PDB
  • 2S to 5S LiPo – Even possible on 6S but not recommended
  • Telemetry capability: Voltage, Current, Temperature, Motor RPM – Only works with KISS FC at the moment
  • Over-current protection – ESC measures the current going through and limits it to 30A max (max current adjustable)
  • Over-temperature protection – when reached critical temperature, ESC power is reduced
  • Adaptive auto-timing – more efficient than fix timing
  • MAX RPM: 450,000erpm, 64,000rpm on a standard (14 magnet pole) motor
  • Accurate RPM control (~ 950 steps)
  • Active freewheeling – common in other ESC’s as well, helps ESC to run more efficiently
  • Supports normal PWM signal (25-500Hz), OneShot125 and OneShot42, protocol auto detected

Size and Weight

The size of the KISS 24A ESC is 19 x 27mm, which is smaller than the KISS 30A of 21x35mm. To be exact, the dimension is 19.55 x 26.94 x 4.19mm.

kiss-24a-esc-littlebee-20a-size-comparison

Weight of the ESC is 3.6g excluding any wires and soldering.

Hardware

KISS 24A ESC RE is currently one of the very few ESC‘s that runs on a 32-bit processor.

Majority of the ESC’s on the market at the moment are based on an 8-bit ATMEL or SiLabs MCU, such as the previous KISS 12A/18A/30A ESC’s (ATMEL), Littlebee 20A (Silabs F330), XM20A (Silabs F390). This reminds me how flight controllers evolved from 8-bit to 32-bit about 2, 3 years ago, same thing is probably happening on ESC.

The 32-bit MCU on the KISS 24A is an ARM Cortex STM32F051 microcontroller running at 48MHz. It allows faster communication and processing, also unlocks the potential for more complex and sophisticated functionality in future development.

kiss esc 24A race edition stm32

No BEC

Just like other Opto ESC’s, the KISS 24A doesn’t come with a BEC, so you cannot power your flight controller directly from the ESC.

FET and Gate Driver

The FET’s are AON6512 N-FET which are actually rated for up to 150A, but in most cases heatsinks are required to run at high current like this. Using high current rated FET’s helps the overheat issue, especially in situations where we try to avoid heavy heatsinks.

kiss esc 24A race edition mosfet

Similar to the Littlebee 20A and KISS 18A ESC’s, the new KISS 24A Race Edition also use gate drivers for faster switching, which makes the motor braking especially fast.

Voltage Limit

The ESC is capable of 2-5S LiPo battery, but on paper it can take up to 25V so in theory you could run 6S with it. However it’s not recommended. Also Flyduino mentioned there is over-voltage protection that triggers at 26.5V.

Firmware

Say goodbye to BLHeli and SimonK, the new KISS 24A ESC runs on a custom firmware developed by themselves.

You will still have the same features like OneShot125, active braking (a.k.a damped light in BLHeli). It also support standard PWM signal and a new ESC protocol, OneShot42.

kiss esc 24A race edition four mini quad

Old KISS users told me that they don’t normally get as many updates as BLHeli or SimonK. It could be a good thing if no one is complaining, means they tend to get things done right the first time. :)

One advantage on Flyduino’s part is they have the control of both hardware and software. I reckon it would make it easier to write the firmware which is specifically for that particular hardware they also designed. Not saying writing ESC firmware, and hardware design are easy, but it enables one to focus more on performance rather than compatibility.

Oneshot42 is a new ESC protocol developed by Flyduino, that is 3 times faster than Oneshot125.

Telemetry

The KISS 24A ESC is capable of sending telemetry data to the KISS FC, such as voltage, current, temperature and RPM. The telemetry data then can be forwarded from the FC to the OSD (MinimOSD) via serial port, and display it on your screen. (Note that it only works with MinimOSD that has to be flashed with their own custom firmware.)

kiss 24A esc re fc

This feature only works with KISS FC at the moment. However this KISS ESC telemetry protocol is open source, so it’s completely possible that other FC get supported in the future.

This opens the door for 2-way communication between ESC and FC, which could be used to improve flight performance of our multicopters in the future.

The Telemetry protocol can be found in this document.

Why ESC burns?

I see this question a lot when people discuss about this new ESC: “is this likely to catch fire like the old KISS 18A?”

So why ESC catch fire? Well, ESC gets hot when it draws current. If you have bad cooling and the heat cannot go anywhere, the MOSTET’s will overheat. At some extreme cases, the MOSFET’s get so hot it eventually melts the solder holding them in place. It will be able to move around on the PCB and causing shorts, which then burns the ESC and goes up in flame!

Flyduino Precaution

Flyduino introduced the intelligent current limiter and over-temperature protection. They basically reduce the power when either the current or temperature reach the max limit, to prevent ESC overheating and burning.

I saw this in action when I was doing thrust tests and I was well impressed: I was testing a fairly powerful setup with this ESC, current draw reached 30A at 80%, but as I continued to increase throttle, current draw just fluctuated around 30A and didn’t go above it. Of course if you wish to set a higher, or lower limit, you can change it in the settings (CLI Mode).

So far we have not heard any burning report on these 24A ESC’s yet.

Update 28/Feb/2016: We have our first burnt 24A ESC LOL – Link here. But really i think it’s just an user error! The prop and motor combo is drawing current way over the spec recommended. (with 5045BN it draws over 27A already, with Triblade 5045BN it will be over 32A for sure)

KISS Race PDB – Flyduino Kiss Carrier

There is a KISS ESC carrier you can get for the ESC and KISS FC. You can sit your ESC’s and FC directly on the PDB, and solder them together. It simplifies the wiring a lot and the build would look cleaner.

kiss race pdb esc fc carrier close up

However the Kiss Race PDB doesn’t fit any of the frames that I have, so I don’t seen myself using it.

The dimension of the PDB is 99.5 x 45mm.

kiss race pdb esc fc carrier

How to use KISS ESC 24A

For the most accurate and up to date instructions, please visit the manual provided by Flyduino.

What Flight Controllers does KISS 24A Support?

It will work on with every FC that supports 50-500Hz PWM, or Oneshot125. It’s doesn’t support Multishot yet.

Connection and Soldering

Typically any KISS ESC’s from Flyduino comes with no wires, you have to solder these on your own. Make sure you have the spare wires in hand or go and get some before ordering these ESC’s.

kiss 24a race edition connection motor fc

You can probably solder the motor wires directly on the ESC. So all you really need is two 16 or 18 AWG wires for power (voltage + ground), and two 24/26 AWG wires for signal (signal + ground). If you want ESC telemetry as well, then add one more 24/26 AWG wire. The AWG number depends on your current draw.

You should solder the signal wire to the pad bellow the PWM label and the ground wire on the left of the GND label. Not to the pad bellow the TLM label (TLM – Telemetry)! That’s the telemetry pad. you must solder both ground and signal, otherwise you might have desync/twitching issue.

kiss 24a esc solder pads led explain

There are 2 more solder pads labelled “TX” and “RX” on the other side of the ESC, they are used for talking to the ESC via serial port. There is also an open solder bridge labelled “BT”, which is the bootloader pin, is used for firmware flashing. I will explain how to use these later in the article.

Calibrate ESC

Flyduino suggests no ESC calibration is required for this ESC because of accurate resonators.

But if you want to calibrate it anyway, same procedure applies as you would do on other ESC. With Cleanflight and Betaflight you could still use the motor tab to do so.

But if you are using the KISS FC firmware/configurator, you can follow these steps.

CAUTION: Remove Props before you start!!!

  • Unplug Lipo battery
  • Move transmitter throttle stick to max
  • Connect Lipo
  • Wait at least 5 seconds, for one long beep
  • Move throttle stick back to 0, wait for ESC to restart (long short long beeps)
  • Disconnect Lipo

Reverse Rotation

You can reverse the motor rotation by swapping 2 of the motor wires, but a much cleaner way is to bridge the two solder pads on top of the ESC (next to status LED).

Running 5S/6S, or 3D mode

If you want to run 5S, (or even 6S – not recommended), or 3D mode, it’s recommended to solder a capacitor across the voltage input of the ESC, because these put a lot of stress on the ESC.

Adding capacitor also helps when you have long power wires. Typically a 220uF on each ESC should be enough.

CLI Mode

You can connect and talk to the ESC with CLI mode (command line) to perform many useful tasks.

A FTDI cable (USB to UART Adapter) is required to connect the KISS ESC to a computer (same tool you use to flash the CC3D). You don’t need to connect the 3.3V or 5V power, only TX, RX and Ground is needed. The ESC will be powered by LiPo battery. To get the computer recognise your ESC and detect serial full duplex mode, you need to connect the USB UART first then the LiPo.

kiss-24a-esc-serial-port-tx-rx-programming-telemetry data

You need to wait 5 seconds after connected LiPo for it to enable CLI mode.

Then you can talk to the ESC with any serial monitor such as the Arduino Serial monitor, or Putty using 115200 baud rate.

There are currently 4 commands:

help - list all the available commands and explain what they do
tlm - print ESC telemetry data
reset - restore all settings back to default
info - system information
CLxx - set max current limit, xx should be 01-30A

For more detail about KISS ESC CLI, refer to this document.

Flash KISS ESC Firmware

You can download the firmware from Flyduino’s site, by entering your ESC serial number there. This way you should get the firmware that is exactly written for your ESC.

To get the serial number, go into CLI mode described above, and enter “info” in the serial monitor. You should get something similar to the following returned.

info
KISS ESC24A Version: 1. 100
Manufacturer: Flyduino.net
Dev.: Felix Niessen
S/N: 20323931-42335719-001C004A
Max. used Voltage: 1503
Current limit (A): 30

Once you downloaded the firmware, simply use the STM32 Flash Loader Demo program to update the firmware as shown in the manual. If you have trouble getting the STM program to read the MCU, try again on a different computer.

Detail instructions of flashing ESC firmware can be found here.

Reading ESC Telemetry Data

There are more than 1 way of reading ESC telemetry data.

  • OSD
  • Serial Monitor
  • Chrome Configurator

Apart from feeding the FC the ESC telemetry data, then displaying it on OSD, you can also see the telemetry data on the serial monitor by entering “tlm” in CLI mode described above.

If you have the KISS FC, you can also read the data from the GUI too. If the FC detects the ESC’s you can use the drop down menu over the gyro & acc graph to choose what you want to see.

kiss-fc-configurator-data-output-esc-telemetry-drop-down

To have the FC detect the ESC’s you will need to power them at the same time, e.g. with LiPo battery connected, the GUI save button will be ignored. (Remove your props)

ESC killing VTX?

If you are using these ESC’s, I strongly recommend using LC filter / voltage regulator in between your FPV gear and the LiPo. The fact that these ESC’s are working so well with active braking, it’s going to cause some serious voltage spikes, which might be enough to damage your video transmitter or OSD.

Even just some capacitor soldered to the power inputs of the ESC’s would help!

In fact I recommend doing this moving forward on any mini quad. ESC and motors are getting more and more powerful, we have heard a lot of reports on the Littlebee now killing FPV gear.

Performance Testing

Hopefully I would be able to test these ESC’s soon on a quad, but before that here are some static thrust test results, from a few different motors, props setup comparing the performance between Littlebee 20A, DYS SN20A and KISS 24A ESC.

Testing Condition:

  • The tests were done using the Turnigy Thrust Stand
  • LiPo Voltage 16.0-16.4 V – Turnigy Nanotech 1800mAh 4S
  • Both SN20A and LB20A are flashed with 14.4 BLHeli firmware, Activate braking enabled

KISS 24A ESC Race Edition performed really well, very efficient and generate more thrust than the other 2 ESC’s in most cases. The Littlebee 20A is surprisingly close in terms of performance, given how cheap it is.

Cobra 2204 1960KV

cobra-2204-1960

Gemfan 5030

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 531 9.4 152.3 3.49
Littlebee 20A 615 10.8 175.0 3.52
KISS 24A Race 635 10.7 173.3 3.66

HQ 5045 BN

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 698 19.5 315.9 2.21
Littlebee 20A 744 21.1 341.8 2.18
KISS 24A Race 787 21.6 349.9 2.25

HQ 6045

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 962 22.0 356.4 2.70
Littlebee 20A 989 22.3 361.3 2.74
KISS 24A Race 1032 23.5 380.7 2.71

Cobra 2204 2300KV

cobra-2204-1960

Gemfan 5030

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 684 13.6 220.3 3.10
Littlebee 20A 734 14.5 234.9 3.12
KISS 24A Race 718 14.3 231.7 3.10

HQ 5045 BN

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 790 25.4 411.5 1.92
Littlebee 20A 879 28 453.6 1.94
KISS 24A Race 862 27.2 440.6 1.96

HQ 4045 BN

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 555 16.5 267.3 2.08
Littlebee 20A 570 18 291.6 1.95
KISS 24A Race 588 18.2 294.8 1.99

Emax RS2205 2600KV

EMAX RS2205 2300KV mini quad motor

Gemfan 5030

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 837 20 324.0 2.58
Littlebee 20A 1002 22.3 361.3 2.77
KISS 24A Race 990 21.7 351.5 2.82

HQ 4045 BN

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 707 24.5 396.9 1.78
Littlebee 20A 720 25.3 409.9 1.76
KISS 24A Race 776 27 437.4 1.77

Gemfan 4045

ESC Peak Thrust – g Peak Current – A Max Power – W Efficiency – g/W
DYS SN20A 498 12.2 197.6 2.52
Littlebee 20A 518 14 226.8 2.28
KISS 24A Race 529 13.5 218.7 2.42

Conclusion

At this moment, I don’t have much to complain about (yet) :) Just before I got the ESC, there was some sync issues with running high KV motors (e.g. 2700KV motors) with 2Khz mode. It was due to an input processing problem with Oneshot high refresh rates. But it was quickly fixed by the team in firmware update. (impressed by the quick responds)

So only a few minor things:

  • Better manual translation
  • Maybe allow users to reverse rotation from GUI like BLHeli?
  • Firmware flash is still not simple enough, maybe that can be done from a GUI like BLHeli. What’s even better would be auto detect version and update reminder
  • And most importantly, more stock :)

I never own any previous KISS ESC’s , so it’s hard for me to say how much better this is and whether you should upgrade or not.

But if you want to get the new features on the 24A, that aren’t offered by the 18A or 30A, then you should consider it :) That’s because these ESC’s are using totally different MCU (i.e. STM32 vs ATMEL), so the capability and firmware would be different as well.

Any questions or comment please let me know.

15 thoughts on “KISS 24A ESC Race Edition – Review, Setup, Guide

  1. Harold Short

    Hi Oscar,
    As a newbi to the quad world your posts have been very helpful. I have built my second drone using the Kiss FC and 24 A escs, the problem I am having is that when the drone is turned on one or two of the motors stay on even when throttle is all the way off. I tried the different escs settings 42, 125 and PWM but cant get them to turn off. Any suggestions

    Reply
  2. ollopa

    I disagree with your explanation of what causes ESCs to burn. In the first place it’s extremely rare for FETs to overheat to the point of desoldering themselves, shifting, and shorting out. In the second place, failure of FETs in the drive section of an inverter is almost always a consequence of the inverter design or gate control.

    There are too many modes of failure to describe in detail but consider the following:
    * Inadequate dead-time (overheats FETs or blows them right away)
    * Shoot through (mitigated by the above, caused by slow reverse recovery time of the FET / body diode)
    * Inadequate gate drive (Rds losses goes way up if the FET isn’t fully on, switching losses go way up if the driver can’t dump enough current to quickly charge the gate capacitance)
    * Oscillating gate drive (blows the gate junction and smokes the FET)
    * Underrated components (FET voltage, for instance, not adequate to handle transients)
    * Lack of a snubber or inadequate snubber to control high voltage turn-off transients

    These are the most common design defects that cause the inverter FETs to fail. Some of these are also what would cause the FETs to overheat, but I’m still very skeptical of the claim that FETs are overheating to the point of desoldering themselves.

    Reply
  3. Krishnakumar

    Hi Oscar,

    You have some great articles! Really love the details you provide…
    I got a KISS FC and the KISS 24A ESCs… After reading your articles, I found that KISS FC can be connected to KISS PDB via the JST 6-pin cable of which 4 wires are for ESC signal, one for ground and ONLY ONE FOR TELEMETRY!!! Does that mean you could combine all of the telemetry wires together and just feed it all to the single port on the JST?? It does not make sense to me to do so but thought I would check if you knew… Reason being, I plan on connecting my 24A ESCs via the JST port 1 by crimping my own wires to avoid soldering… Please let me know your thoughts and keep up the great work with your articles!

    Reply
  4. Daniel Ribeiro

    Hello Oscar, nice blog, everything I search on Google ends here!
    So I’m worried about the Voltage Spikes that ESCs do when Damped Light is enabled. You recommend to install an electrolytic capacitor on the ESCs power inputs to protect the quadcopter electronics, but how about the battery? Do you think this problem can reduce the battery life by frying the cells for this short time bursts?
    Best wishes!

    Reply
    1. Oscar Post author

      I wouldn’t think so. LiPo has very high discharge rate, and many of us can cycle the LiPo batteries 100+ times without problems (if it doesn’t get destroyed during flight before that).

      Reply
  5. Ryan

    Hi Oscar,

    Great review. Did you have success testing the RPM control feature? I am not having any luck. In the specifications it advertises “Accurate RPM control ~ 950 steps”. I tested a few ESCs on a thrust rig with an RPM monitor. The RPM changes with battery voltage like it does with every other ESC that lacks RPM control. Any ideas on why this may be?

    Thanks!

    Ryan

    Reply
  6. Jiri S

    Hi oscar,

    I need your help. I have Kiss FC with Kiss esc 24 race edition conncting to the emax 2204/2300 motors ane I have desync/twitching issue same as in these video

    https://www.youtube.com/watch?v=sPpryPy6yqk

    wire layout I have according to the instructions, including telemetry. Any idea what to do?

    Thanks Jiri

    Reply
  7. Jeremy

    Hi Oscar,

    Thanks for your article. Do you find a suitable frame to put the Kiss carrier ? I’m looking for a 210mm size.

    Thanks

    Reply
    1. Oscar Post author

      unfortunately it’s too big for most 210 frames. You might have to consider a 250 frame if you want to use the Kiss Carrier, like the ZMR250 or QAV250 should work fine. maybe use some shorter arms on the ZMR like 5″ to make it lighter LOL :)

      Reply
  8. Mpkiteman

    Hi Oscar.
    I’ve read with a lot of attention your review.
    I’ve tested those escs, and my opinion is positive, but…

    I explain : I have the combo Kiss FC and Kiss ESC.
    And believe me, if you want to enjoy the full Flyduino experience, you must run this combo.

    With my first FC, I had some problems certainly because of the integrated voltage converter.
    Flyduino replaced it veryyyyyyyyyyy quickly, and I could fly…
    The difference with the Littlebees, it’s the smoothness of the motors.
    They really spin with no noise, it’s butter…really fantastic.
    BUT …
    after 2 flights and had problems with one esc, and 2 flight further with another one !
    A bad batch ?
    I hope…
    First ESC showed me wrong voltage of my 4S battery in the osd (19V…). I removed my battery, then this one never worked again : no smoke, no hits, no green led…nothing.
    Second one…I hate this second one, because my quadcopter fall off the sky without reasons.
    When I discovered my quad, this esc was beeping all the time with green led flashing very fast…
    Impossible to initialize it again. https://www.flickr.com/photos/[email protected]/shares/3E33t8

    Every faulty part has been replaced very quickly thanks to Flyduino, and this very important to understand that behind those electronic parts there’s a really reactive team, and they develop themselves their products !
    They really care about their customers.

    So,to resume : combo Kiss FC and Kiss 24A esc = fantastic flights, so smooth, you won’t believe it…But in my opinion there’s some production problems due to very young and complex products :

    – Sometimes, users with quads equipped with Kiss 30A esc are falling off the sky without any reasons (with mine it was with 24A Kiss ESC…) Flyduino is investigating.
    – Be careful with the USB connector on the Kiss FC (put extra solder on both sides of the connector) but actually this is solved by Flyduino, because the verify each FC one by one before selling them.

    Reply
    1. Oscar Post author

      thank you :)
      i actually heard similar stories from other people as well and i pointed those potential problems in my KISS FC review.
      however i have yet experienced them myself

      Reply
    2. Mark

      Hi Oscar
      i have made an awfull mistake of soldering the ground signal wire to the TLM pad and now it wont even light up. Is there a fix for this problem thanks
      mark

      Reply
  9. Alessandro

    Hi Oscar!
    As a German, i enjoy the privilege to buy KISS ESCs local with cheap and fast shipping so me and my friends fly KISS for quiet some time now.
    As for me, KISS 12A and 18A gave me the best flightperformance compared to every other ESC with every Firmware.
    Now i have the KISS 30A on my 6S Setup and they work great, the copter is “snappier” and more locked in than compared to all the others.

    On Youtube there are also many videos where people yaw with normal ESCs and KISS escs, you can see and hear the difference.

    Yes there were problems with burning KISS 12A and 18A with v1.0 and v1.1 but they pretty much fixed that.
    As for me: I did feel a noticable difference in my MiniQuad but also my XXL 6S Copter and im sure you will “feel” the difference too ;)

    Reply
    1. microsky

      Hi, Oscar,

      Thank you for the information.

      But would like to see to compare with DYS XM20A instead of SN20A, as SN20A is the old esc, XM20A is the latest one.

      Would like to see how it works with this Kiss 24A.

      BR,

      Reply

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