I just updated my Smart Controller to v4.3.25. Now the battery discharge time can be changed. I set mine to two days. Suppose I am set to fly and something comes up where I can't on day one. Day two and three it is raining. The batteries start discharging and on day four I am set to fly again. I don't know how much the batteries wil discharge in a day or two, but lets say they are at 85%. Is it okay to charge them back to 100%, or should I fly with them at 85% and run the batteries down to the usual 20% - 30% and then charge them up?

   If it is not okay to recharge at 85%, what is the safe level to recharge?

well the general consensus of opinion is don't fly unless batts are fully charged, so charge em up till fully charged

dji manual says always launch without full  - i have flown with discharging batteries and thank fully not suffered issues - however if i did suffer and issue which resulted in a dispute with dji they would likely simply state that launch was without full battery and therefore the loss (or issue) is my own responsibility.