Seemingly premature power exhaustion

[outermagnolian]

On two flights this week my new unit, with at least 25% remaining battery, just dropped. Props still spinning under power but rapid loss of altitude resulting in a crash. First time, it hit the beach. No harm but confusion. This morning it fell short of the beach by about 150 feet. A watery grave in 30 feet of ocean

What is happening? Should the unit lose lift with solid battery life remaining?

 

[OI Photography]

On two flights this week my new unit, with at least 25% remaining battery, just dropped. Props still spinning under power but rapid loss of altitude resulting in a crash. First time, it hit the beach. No harm but confusion. This morning it fell short of the beach by about 150 feet. A watery grave in 30 feet of ocean

What is happening? Should the unit lose lift with solid battery life remaining?

Yes. You don't run your battery down to 0%, after 30% you don't have "solid battery life remaining." The physics of power supply over battery capacity aren't linear...once you get below 30% their ability to deliver current drops like a rock (or a Phantom).

And it can ruin your battery.

 

[tanasit]

You may want to change the FS voltage level setting, so that after the first warning you have more time before it starts to land itself. You want to have 20% or more capacity left in the pack after the flight to ensure long service life of the pack.
It is a good practice to use the time for ALL flight.