title_body: My DIY Project - My motors and voltage regulator for water pump does not work at the same time I am working on a project to make a quadrocopter that can spray liquid material. Unfortunately, I had this problem: when I give full thrust and try to activate the water pump at the same time, the water pump won't respond. However, if I stop the rotors and then activate the water pump, it will work. What can cause this?
  Flight controller: K++ Jivi
  Voltage regulator: similar to this one
  The water pump is being controlled by a voltage regulator that connects to the flight controller like a servo pin (for those who know this flight controller, the VR is attached to pin: EXT1 -&gt; P2).
upvoted_answer: If you are using the same battery for everything, the drone rotors might be drawing too many amps causing your pumps to not spin. Try using an external battery for it, or get a bigger battery for the whole drone. And if this doesn't help, please explain your setup a bit better.