Since its release, the CLRacing F4S has proven to be a very popular flight controller offering excellent performance for the money and packed with loads of features. However, despite the best design efforts, it is close to impossible to predict how the board will respond to the thousands of possible quadcopter configurations. Recently some users have been reporting random spin of death crashes with this board.
Cheng Lin, the designer of the F4S has confirmed that some of the ESC on the market are particularly noisy, and this noise can cause a random large voltage spike. This voltage spike can affect the ground plane on the FC causing the processor to shut down.
So far the following ESC are confirmed to cause this problem:
- EMAX Bullet ESCs
- Kiss ESCs
- ZTW Polaris 25a ESCs
- LittleBee Zeus ESCs
However it is not limited to just these ESC.. fortunately, there is an easy fix
How to fix this (use low ESR caps)
The easiest way to solve this is to simply add a low ESR capacitor (220iF or 330uF 35V) across the power pad on each ESC. If you don't have enough space on your ESC, you can also add a 1000uF 35V Capacitor across the battery connector, but adding a cap to each ESC is always the best solution. This is because you are adding a cap closest to the source of the noise (the ESC).
Where to buy
CLracing is also working on a modified design for the F4S to help mitigate this problem, and also many ESC manufacturers are also including many more capacitors on their ESC to avoid this on any other FC. In general though, its always a good idea to add a cap across each ESC, particularity if you are having noise issues irrespective of hat FC you are using.