Review: Crazybee F4 Pro Whoop FC (V1 V2 V3 Changes)

The Crazybee F4 Whoop FC is designed by Happymodel, originally for brushless Tiny Whoops but are now also used in ultra-light micro quads, such as my favourite Sailfly. It’s a compact and light weight solution, as the radio receiver, FC and 4in1 ESC are all integrated into one single board.

The Crazybee Pro F4 FC is evolving fast since the V1 came out in 2018. We will check out the latest V3.0 in this post, and also talk about the changes they made to V2, V2.1 and V3.

Note: the Crazybee F4 Pro FC is designed for brushless motors, NOT brushed motors.

For more Whoop Style flight controller, check out our whoop FC round up.

Differences in V1.0, V2.0, V2.1 and V3.0

Here are some of the biggest differences between each version:

  • V1.0 can only handle 1S – 2S LiPo, 5A ESC
  • V2.0 supports 1S – 3S LiPo, bigger receiver bind button and boot button, the battery lead solder pads changed to through hole
  • V2.1 – stronger voltage regulator but only supports 2S – 3S Lipo. Camera and VTX is now connected to the FC via plastic connector instead of soldering pads
  • V3.0 supports 2S – 4S LiPo, ESC upgraded to 10A. A few things have gone back to how it was before due to the lack of space: no longer using plastic connector for VTX and camera, just solder pads now; And bind and boot buttons reverted back to the original tiny ones; built-in current sensor

Why you should add capacitor to the battery lead?

How to Bind Frsky Receiver?

Crazybee F4 Pro V3

Product Page: | Amazon

The CrazyBee F4 Pro V3.0 was released in July 2019. The first BNF model that uses this FC is the Eachien Cinecan 4K.

The biggest changes are probably the 2S – 4S LiPo input support and the ESC’s current rating are doubled from 5A to 10A (each). The ESC MCU are upgraded too, but they are still running BLHeli_S.

They used larger push buttons for receiver bind and bootloader mode on the board, but decided to go back to the very small buttons they used in the V1, possibly due to the lace of space.

Here is the specs of the Crazybee F4 Pro V3:

  • Processor: F4 MCU
  • Gyro: MPU6000 IMU
  • Built-in Betaflight OSD
  • Weight: 4.3g
  • Board size: 28.5×28.5mm
  • Input Voltage: 2S – 4S LiPo (7V – 17V)
  • Built-in Blheli_S 4in1 ESC
    • ESC Current Rating: continuous 10A, burst 12A (each motor)
    • ESC MCU: EFM8BB21
    • ESC Protocol: Dshot600
    • ESC can be flashed and configured using BLHeliSuite via FC passthrough
    • ESC firmware: F_H_40_REV16_5.HEX
  • Built-in RX and No RX options available:
    • Frsky SPI receiver with telemetry (D8/D16 switchable)
    • Flysky SPI receiver with telemetry (AFHDS/AFHDS-2A Compatible)
    • Spektrum DSM2/DSMX compatible satellite receiver (Default RX2 was used for DSM2/DSMX receiver)
    • The “No RX” version supports external serial receiver such as XM+, Crossfire, S-FHSS and DSM2/DSMX, iBus
  • Built-in Current sensor with maximum capacity up to 70A
    • Please set Current Meter Scale to 470
  • Built-in 5V 1A voltage regulator with LC filter for clean FPV Video
  • Built-in voltage detection

IRX1 – inverted for Frsky SBUS. RX1 – normal, not inverted.

Crazybee F4 Pro V2.1

Product Page: | Amazon

In May 2019, a minor updated version the Carzybee F4 PRO V2.1 was released.

Not much has changed, mostly just changing the connector interface for FPV setup – from solder pads to a 5-pin SH1.0 connector socket. This version no longer supports 1S, some suspected that the 5V regulator has been upgraded.

Crazybee F4 Pro V2.0

Product Page: | Amazon

In Jan 2019, Crazybee F4 PRO V2.0 flight controller was released, supporting 1S – 3S LiPo. They also replaced the tiny buttons for bind and boot with some bigger push buttons, making it easier to use. This FC is used in the Mobula7 HD (with Turtle Camera).

Crazybee F4 Pro V1

Product Page:

The Crazybee F4 Pro V1 is a step up from the older CrazyBee F3 Pro. Not only it has a faster F4 MCU instead of the F3, they also added an extra UART bringing the total number of UART’s to two.

The CrazyBee F4 Pro boards were introduced with the popular Trashcan 2S brushless whoop and as well as the Mobula 7 (new version). Betaflight firmware target was added since Betaflight version 3.5.5.

Note that the RX1 Input of the Crazybee F4 Pro FC is designed for radio receiver input, therefore it has an inverted input for SBUS (pin labelled IRX1). If you wish to connect a non-Frsky serial receiver, make sure to use RX1 which is not inverted, not IRX1.

There are solder pads available on the CrazyBee F4 Pro FC for connecting RGB LED and buzzer.

There are four different receiver options, each with a different betaflight firmware target:

  • CrazyBeeF4FRPro – Frsky
  • CrazyBeeF4FSPro – Flysky
  • CrazyBeeF4DXPro – Spektrum
  • CrazyBeeF4Pro – Without receiver (you can add your own external serial RX)

Add Capacitor to Prevent FC Burnt Out

On May 17th 2019, Happymodel made an announcement to address a common issue with burnt out boards, which tends to happen as soon as users plug in the LiPo battery, frying ESC MOSFET and 5V regulator.

They believe the problem was caused by users changing out the the PH2.0 battery connector to the lower resistance XT30. This was done on purpose to “boost” the power of our quads, but unfortunately also leads to more severe voltage spike when you connect the battery to the quad. Apparently, using batteries of lower internal resistance (higher discharge rate) and higher capacity can also make matter worse.

Happymodel proposes a simple solution, which is to add a low ESR capacitor to the battery lead. This capacitor should have an ESR lower than 0.2ohm and have a capacitance of 100uF or higher. They recommended Rubycon ZLG/ZLH series and Samyoung NXB series.

The image below shows how much voltage spike a 100uF capacitor can reduce when you plug in the battery.

A 100uF Capacitor should be enough for 3S 300~350mah battery on the Crazybee F4 PRO V2.0 and V2.1, and 2S 300~350mah battery for the V1.0. For batteries larger than the 350mah mark, they recommend using a 220uF or larger capacitor.

With the Crazybee F4 PRO V3.0, they no longer supply a capacitor for this board. So it’s now up to you whether to solder an extra cap to the power or not.

This seems to be a reliable fix to the issue, hence many new pre-built kits with the Crazybee F4 Pro FC now come with a 100uF capacitor soldered to the XT30 pigtail, such as the Mobula7 HD and Sailfly-X.

You can solder up the cap by yourself, or just buy this pigtail:

Binding Frsky Receiver

You can bind the built-in SPI receivers in two different modes, FRSKY_D (D8) or FRSKY_X (D16). Although you can get telemetry with D16 mode, but we recommend D8 mode because it offers better range.

Before binding, go to Betaflight’s configuration tab, and change “SPI Bus Receiver Provider” to the one you prefer.

Then go to your Taranis, under Model Setup, Internal RF, you need to change mode to either D8 or D16.

There are two ways to bind the Crazybee F4 Pro to your radio if you are getting the Frsky version: by holding down the bind button, or through CLI.

Bind Button

  1. Connect LiPo battery to the quad
  2. Hold down bind button for 2 seconds until the LED becomes solid
  3. Enter bind mode on your Taranis
  4. If binding is successful, the LED on the quad should start blinking
  5. Reboot FC, Done!


  1. Connect the FC to computer, open Betaflight Configurator and go to the CLI tab
  2. Enter this command to force FC into bind mode:
    • For Betaflight 4.1: bind_rx, BF4.0: bind_rx_spi, for BF3.x: frsky_bind
    • Enter save
    • The red blinking LED on the FC should now stop blinking
  3. Activate the bind option on the radio
  4. Wait a few seconds, then stop the bind function on the radio
  5. Reboot FC, Done!

35 thoughts on “Review: Crazybee F4 Pro Whoop FC (V1 V2 V3 Changes)

  1. Tojo

    I’ve got a CRAZYBEEF3FR board from my Mobula7 and made the mistake of updating the firmware to 4.0.6 recently.
    After having to fully reconfigure my binding, switches and betaflight configuration still two problems remain..

    1) drone is randomly looking link to the radio and falls from the sky, no signal response from radio even walking right up to the drone. Not until the drone is powered off/on again. I’m operating on D16 no telemetry.

    2) battery voltage seems completely erattic now. I used to fly for several minutes without major voltage drop. but a brandy recently charged battery is dropping to 7.2v-6.9v after only a short flight.. I’m seeing only about 20mah usage. These are new batteries and have only had 2-3 charges.

    Still playing around to see if this stuff can be corrected. I really like this as a starter drone..
    Is the board the problem (ie not supported by betaflight at this point) or is this just a configuration issue I need to work out?

  2. skywinder

    Hi. After crash my radio start to loose signal, and in the end lost it completley.
    Now my radio signal not recognized by mobula 7.
    Can’t re-bind it again too.
    Just want your recommendation: what can I check, is it possible to fix this? is anyone got this issue before?

  3. jose

    i just installed the new V3 crazybee board. it has no capacitor on the lipo leads. Can i still install a capacitor there to make sure it wont burn the 5v reg that happened on my ver 2.1 board ? thanks

    1. Oscar Post author

      one of the improvement they made in the V3 is to prevent issues like burning out 5V BEC in the V2 boards :)
      You can still solder a cap to the lipo pads though.

  4. Pyty

    Hi Oscar, you can fix one output esc in these crazybee? i have 3 of 4 differents versions with problems in one ESC in 1s and 3s…

  5. Chris

    Hey Oscar, just letting you know your link In the sentence “For more Whoop Style flight controller, check out our whoop FC round up.” actually links to you AIO FPV CAMERA & VTX COMBO ROUND UP.

  6. Mike

    I can’t seem to get an led strip to work on the f4 v3 version. I have connected the wires to a ground, a +5v, and to the led pad on the FC. I am using Ws2812 LEDs, but, it doesn’t seem to want to activate them. I have attempted to change settings in betaflight to enable and change them, but nothing happens. Is it not supported on the v3 version of this board?

    1. Oscar Post author

      have you tried the LED strip on a different FC? just to ruin out the possbility that the LED strip is faulty.

  7. yannick

    hello. i do have problems with internal rx so i decided to pur on an external rx as frsky pro… to have better reception. so I bind my receiver with my jumper t16 pro. the led is green solid but nothing happen in betaflight… Do i have to power off the internal receiver and how can I do that???
    best regardes

  8. Are

    Bought taranis X9d 2019, running 2.3.7
    Sailfly Frsky
    Betaflight connects (10.4, 10.5.1 and 10.7). Everything works in betaflight but Cannot bind from cli or manually. Tried D16 with almost all firmwares from 4.1 to latest . I can easily bind it to older taranis x9d+ in D8. Ideas?

  9. huck

    I bought the v3 with no RX since I’m a spektrum person. I bought a BetaFPV DSMX Rx to use with it. The Rx has 5v + and – wires I need to solder somewhere. Is there a second set of 5v+ and – pads on the v3 besides the VTX pads? I hate the idea of doubling up the Rx and VTX power wires on there and I see lots of pads that are not labeled in all the pics of the v3 board that I have found online. Thank you

  10. Andrew

    Do you think you could improve the reception of the on board receivers by soldering a length of old laptop wifi coax in place of the existing antenna? Need to solder the outer shield to ground?

  11. ErikWTN

    Great article! A ton of good info in here. Thanks!
    BTW, they changed the CLI bind command again for BF 4.1, it’s now just “bind_rx”.

  12. Vladimir Cerovic

    My new crazybee f4 v3.0 causing problems :( My v2.0 burned so I bought this one. Installed in mobula 7 hd. Bind, set switches. When I apply throttle, Motors go nuts and drone tries to flip or something and disarms… Any help please? Individual motors work fine in motors tab of BF. I use frsky and x lite.

  13. Tb

    Hi Oscar!
    (Sry my bad english)
    I have a Mobula 7, with F3 Pro FC. My soldering pads (Lipo + input) was damaged.
    Soldering is not possible. Where can I solder the (lipo+) input current? Is there another option?

  14. Casey

    You have to type in “save” in cli after you bind it to your controller then cycle power to the flight controller then it should stick

  15. Raul

    Hello. I have installed an R-xsr receiver on the cracybee f4 pro V2 controller in f.port mode. But I can’t make it work.

    The receiver had it installed in another free drone and it worked perfectly. So he ruled out receiver failure
    Any ideas. I have followed the Oscarling tutorial for the cli commands but none has worked for me

  16. andres pinzon

    Hi, I´m desperate trying to connect to a devo7e dsm2 mode. I tried everithing: CLI , bind button and it doesn´t connect. I Have the F4dx pro v2.0 crazybee . I configurate 1024 spektrum UART 2 and in the transmitter removed the fixed ID, put in bind mode on dsm2. I don´t know whats else to do. Thank you

  17. Joe

    I also want to build a Kabab toothpic on 1s. I used an older crazybee f3 board, 0802 motors, a runcam and an eachine vtx.
    The eachine vtx goes from 25 to 400 mah and needs 5v, just like the cam. I soldered everything to the f3 board, and it worked for 30 sekonds, then the voltage regulator went up in smoke. I should have known.
    Now I ordered a crazybee f4 v2.0 board, because I want to start with 1s. Question: Can I connect the vtx to 5v, or will I blow the f4 as well????? I can’t find any information on this!

    Thanx in advance,

  18. Colin MacKenzie

    wonder if some one can suggest a bit of advice. I have a Crazybee F4 2.0 pro with Spektrum on board. the first problem is when i use the CLI and enter either set spektrum_sat_bind=9 or 5, I tried both and both make the board go into bind mode, then bind it, it will bind. But if i unplug from the Battery and plug it in again it does not go into bind until i put it thorugh betaflight and repeat the process above. I can keep it to stay in the bind mode. I have to repeat the process through betaflight to get it to go into bind mode. The 2nd problem is after I get a bind it will not arm. I have gone through all the suggenstions i could find in the blogs and such and it will not arm. Radio is working and it FC is resonding. One test I did was to bind it on the usb. THen goto the motors in betaflight and enable them. I could then spin them up and down with the radio. I unplugged it from the radio and could get it into the air BUT the rolls were reversed. I brought the quad down and unplugged the batter and of course lost the bind and was in the same boat as the start. I travel on my radio is all correct as far as i can tell. the CLI does not report any errors , other then the normal ones you get about it being on betaflight and such. when i enable my arm switch i can see betaflght showing they are there but the ARM never goes yellow. I have set all my travel on betaflight between 1000 and 2000 and the min is set to 1050 so i know it is not my throttle so high to arm. Man, i am exasperated with this. I really want to get this going. Oh and one thing. The board shipped with betaflight_4.0.0_CRAZYBEEF4DX_20181211.hex and that would not allow any of the modes in betaflight to be displayed so i flashed with the latest version of beta fight for the FC. I even put the original version back on it and checked it and nothing. Currently i have Betaflight / CRAZYBEEF4DX (C4DX) 4.0.6 Sep 1 2019 / 00:26:33 (2a64051a2) MSP API: 1.41 on it.

  19. Perbowo wicaksono

    So no love for 1s on crazybee f4 v3? Or is it still can be done? Planning to buy one for building kabab toothpick spec. Thanks


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