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.

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

Why you should add capacitor to the battery lead?

How to Bind Frsky Receiver?

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.

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.

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).

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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)

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, I believe you still need to do the same.

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:

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.x: bind_rx_spi, for Betaflight 3.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!

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Passion for planes, flights, aeronautical engineering and eager to share my knowledge and related areas of interest.

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