There is real data to back up this question.
An organization did a test on Tesla battery systems with different discharge depths/cycle life and came up with a measurement curve. The experiment was measured in a total of four case scenarios :.
1. 0%-100%, i.e. full discharge;
2. 50%-100%, i.e. full discharge and then recharging after using half of the charge;
3. 25%-75%, i.e., after reaching 75% full capacity, charging was stopped and then started after 25% use;
4. 0%-50%, i.e. start charging from 0%, after charging to 50%, stop charging and continue using to 0%.
In the above test, it can be found that under 0%-50% charging and discharging conditions, the cycle life of the power battery is the longest, and it basically doesn't decay much after 3,000 times of charging.
In the 100%-0% deep cycle mode, after 900 cycles, the capacity decayed to 50% or less.
So it's not as if a full charge and discharge will improve battery life. And of course, it's basically impractical to use it below 0% and then recharge it.
According to the curve of the Tes battery, it can be found that 25%-75% charging and discharging is still more reasonable.
We have also asked the engineers of the car company about this issue, and the answer we got is that it is recommended to charge the electric car when the remaining power is about 20%.