Furthermore. You can push your
mini 4 further than the 18% if you absolutely have to. Quite a lot further in some circumstances. You cancel the RTH when it first tells you it's doing it in 10 seconds, and (unless you are in crazy wind) for a few mins you can carry on flying...
If you tap the battery meter whilst in flight you get 3 very useful times:
1. Time to RTH at 18%, allowing you to see it coming and plan for it, and allow it to happen, which is best for your battery, best for the craft, for your mental health, and generally best for everybody
2. Time to Forced Landing: Letting you know how long you have before it descends on its own. You can still oppose this with upward stick movement btw !
3. The time until the battery is genuinely empty, ***** itself and you fall out of the sky. Flying it down to that last number is madness - never do that, obviously.
With that said, once you are at Time 2, and it starts landing on its own, as long as you continue to mix solid up commands with your directional ones, you can travel a surprising distance home if you find yourself in that horrible situation ! But for god's sake don't rely on it, or do it in anything other than an emergency.
A quick example of such an emergency might be:
Say you took off for a Cineflight into moderate wind, and flew 500m out against it (sensible, so it's behind you on the way home), and you spent down to 25% power getting the shots you wanted. But now you need to get home, and the wind has reversed direction, and increased quite a lot. Now it's a struggle to get back, and power starts subsiding at alarming levels while the drone fights it. You get to 18% in what feels like no time. But if you just do RTH here it's gonna fly up to your safety altitude where the wind is much, much stronger, and you'd be dealing with that on a weak / low power pack, starting a vicious cycle that may well end in craft down. So instead, we can countermand the RTH before it happens, manually DROP our altitude to as low as we can safely get, and make our way home, holding the up stick when the craft starts descending on its own. Many have been saved from death this way ! It does have a detrimental effect on the pack when it is forced under 3.2 volts per cell, and much moreso and more quickly if you ramp it to the minimum it will allow before it falls out of the sky, which is 2.7v