Coming down is harder than going up

If you asked someone if a quadcopter took more energy going up than coming down, I believe most would say "going up".

But that isn't always true.  When a multirotor comes straight down, it is flying in its own downwash, which is very turbulent. Coming straight down too fast is a bit scary when you see how much the craft pitches.  Sometimes you might think that it is going to crash.  And that can happen - especially if the P-I-D control parameters are not set properly ("I" value set too high).

I have been practicing going straight up, then straight down.  I have the "up" speed set to 8 meters/second (26 feet/second or 1,560 feet/minute).  I have the "down" speed set to 3 meters/second (588 feet/minute).  Coming straight down much faster than that is not advisable if you have a craft with props larger than 10".  Bigger props have more trouble with stability while coming down. Side winds can add to the instability.

So, the time it takes to go up is less than half the time it takes to come down.

If - for example only, you wanted to climb to 1000 meters (3280 feet) with a craft that weighed 2.4KG and had a 3 - cell (12V battery).  I calculate that the battery current would be 75A during the climb.  That is 900Watts!  Coming down, I calculate that the battery current would be about 35A, which is about half the power used during the climb, but the time it takes to come down is MORE than twice the time it takes to go up. 

As a result, it takes more total energy to come down than to go up!  

Also remember, to produce the same amount of power, the current must go up as the battery voltage goes down (Watts = Volts X Amps).  That means that the current required for anything (climb, hover, etc.) will go up as your battery voltage falls - causing your battery voltage to fall even faster. Battery remaining capacity falls faster than battery voltage.

If you are someplace where you can try for an altitude record and you have less than 50% battery remaining at the maximum height, you are screwed UNLESS you can come down at an angle - where you don't have so much trouble with downwash and can come down faster.