Litchi app, log file, flight replay, battery problem?

[AzDroner]

P2V+V3
Flew the drone today, short flight, landed and turned off.
Turned on again and launched another flight with 70 percent battery left according to my litchi app. Seemed to stay at 70 percent for long enough to make me concerned, so I brought it close to me to keep an eye on it. The percent started to decrease so I flew the drone around until it reached 29 percent and kept trying to auto land. Got it landed, (should have hand caught) and it flipped over up side down. Only damage, nicked one prop.
Took a look at the litchi log in flightreplay and found the following:
Flight log gives 10 lines of data per second. Got 4040 lines of data.
This flight was 6 minutes 40 seconds long
Started this flight at 70 percent battery
Battery stayed at 70 percent for 2 minutes 9 seconds (Normal? I don't know)
Battery percentage then dropped one volt every 5 to 8 seconds down to 30 volts.
This is dji battery with 48 charges on it, I've now discharged it down to 8 percent and charged it up again, will see if that changes anything.

 

[Fourprops]

I definitely would keep it no higher than 5 to 6 feet keep an eye on it. I was told when these batteries get around the 50 charge Mark it's time to get a new one

 

[Mark The Droner]

Frequently I see posts like this where the battery behaves oddly after having launched with less than a fully charged battery. The sticker on the bottom of my Phantom says "Never launch without a fully charged battery." Words to that effect. Why? I don't know. But maybe there is something going on that we can't explain. Maybe we should always launch with a fully charged battery.

 

[MapMaker53]

Interesting. My P2V+v2 doesn't have that sticker and I have often flown on 50-75% when putting it back into the air just to get a few quick photos as long as I have a reasonable amount of charge left. But I don't keep it up longer than a few minutes and always return before hitting 30%. Also, I never send it out further than 75 meters or so on a partial battery because I know there are cases where the charge suddenly drops.

 

[Mark The Droner]

I've got a Vision. On the bottom of the craft there are two stickers. One is a QR code and the other is a larger sticker with the S/N. But below that in tiny letters, it says Check List Before Every Flight!

And below that, the third bullet says "Always check the battery status, and start the flight with a fully charged LiPo flight battery."

I used to think nothing of starting off at 70% or so, but I stopped after reading some of the posts on this site.