title_body: How do I tell when to replace the motors on my tinywhoop? I own a brushed micro quadcopter, more commonly known as a tiny whoop. I've read that brushed motors in general, and especially those used in such quadcopters, have a limited lifetime and that you should replace them when they near the end of that lifetime. 
  
  However, as far as I can tell, there are no obvious signs that the motors have become too old to fly, as they don't break but instead their performance decreases over time. There's a maximum total runtime in hours listed for the motors, but I can't imagine any way to track how many hours the current set has been flown for besides writing down the length of each flight, which would be extremely tedious.
  
  So how do I figure out whether my motors are worn out and should be replaced, or are still okay to fly with?
upvoted_answer: As someone who loves collecting data for analysis, I do track all of my flights.  I have found that, under normal conditions, brushed motors should last for at least a few hundred flights.  You can get higher if you don't fly hard or get things caught in the props or motor shaft that will make the motor heat up more than normal.  
  
  How to determine whether a brushed motor needs to be replaced is a tough question and it really depends on your willingness to fly with a drone that isn't operating perfectly.  With mine, the telltale indicator is that I notice less power than usual and yaw is off a bit (twitchy or lethargic).  This makes sense since all motors perform to the level of the least capable motor.  If you experience less performance, first, ensure that it's not just the battery.  This is easy to do - just use a newer battery, or one that you know is still providing good power.  The next thing to do, if the battery checks out, is to replace the motors.  I recommend replacing all of the motors at once for brushed motors since they are all getting some form of wear while in use.  Replacing them all ensures that you are starting with peak performance.