title_body: What happens when a multirotor runs out of battery mid-air? If I am flying a multirotor drone and it runs out of battery mid-air, what will happen to it? Will it just fall down from the sky or will it give me a low-battery warning?
upvoted_answer: Assuming that you ignore all of the warning signs that your battery is low, while also assuming that you can completely deplete the voltage in your battery, the drone will ultimately reach a point where it is still providing power for the motors to spin the props, but the props won't provide enough lift to keep the drone in the air. 
  
  The drone will start to descend slowly and will increase descent the longer time goes on.  If you are a few feet off the ground, it might look like a soft landing.  If you are a few hundred feet off the ground, it might be a hard crash.  There will also be a point where the voltage cannot provide enough power for the flight controller and receiver and other electronics on the drone, which will shut them down and at that point, if the drone is still able to fly, it will drop since motors will not be spinning at this point.
  
  The last scenario is not likely to happen since the main electronics tend to run at very low voltages, so they will have power for a while after the motors stop spinning fast enough to provide lift to the drone.
  
  The drone won't just give you a warning when the battery is low.  You, or the maker of the drone, need to set that up.  If it's already set up, then you should have all you need to avoid a low voltage scenario.