I was wondering what the optimum settings for the battery are. I currently have my low battery set at 30% and return home at 15%. Is this ok, or should I go higher, lower? What is yours set at?

Good question. I think I have the same settings

The answer is going to depend on a lot of factors.
There's no one-size-fits-all solution.
If you just fly around the park you would have different requirements from someone that flies 4 kilometres out

I have a P3S and I'm not confined to a park. However, I am confined to the max distance allowed by the DJI program on the P3S.

In warm weather I would have it at 20 and 10.  BUT in cold weather I would have it at 30 and 20.  Also it depends on your experience level, and your experience with the machine.

Always start with these numbers a bit I higher  and then lower them to increase flight time but retain safety.

donnie

One mistake you made in your post, the lower number is the critical low battery level, that does NOT do a RTH. It's will land at the location it's at!! The Smart RTH that is done by the Go app does that.

wmcvey,      Yea I should of remembered that. When the battery gets low it lands because the battery is getting weaker therefore the motors are slowing down and the drone is coming down because of the battery running out of power. Unlike my toy quadcopters, the battery goes from live to dead and it'll fall out of the sky. No warning. I do know the Phantom will return to home when you go out of range. Had that happen last week.

I use 40 for low and 10 for critical.  I want plenty of warning at 40, or even 45%, so I'm sure to be concentrating on wrapping up what I'm doing and get back.  I want 10, or slightly less, because I want all the time possible to get it back before it lands whether I want to or not.