Hi all,
I see other similar posts but not sure if my situation is the same.
I flew starting with a fully charged battery for approx 3 mins bringing Battery to 83% then another flight 2.5 mins taking the battery to 69% , Then a supposedly quick vertical to about 20m to do 1 Pano shot from a lookout point, Battey was 50% at take off, Looking at the log , the Battery voltage dropped from 14.9v to 12v in a split second at the 2.5second mark, Once I reached the height of about 23m I sticked forward to move the drone out of the sun before intending to rotate for the footage. The log for the 1st flight seems to have a bit of weird battery info showing a drop then an increase? The % does not seem to change with the voltdrops .
The Drone just dropped to the ground, smashing the gimbal and landing gear.
I have had the drone approx 8yrs ish, cant remember exactly, Have not used it a lot (3 x Batteries, 16, 21 cycles and the relevant battery 18 cycles) Total for the drone since new.
What do you think caused the drop from the sky?
What Voltage does the drone cut or switch off at?
All software and firmware is up to date and no warnings came up.
I was using Litchi
I know we should use a fully charged battery each flight but after just a few minutes of flight from full charge, I would not expect to have the drone cut out.
If this is a battery issue, How can we check batteries for possible issues before use? These Batteries were nearly $300 each at the time so I want to check them properly before discarding them.
1st Flight log - https://www.phantomhelp.com/LogViewer/38MU7QZ468L86GKVR58N
Crash log - https://www.phantomhelp.com/LogViewer/1Y7W55CLFRHJR20ZNV8L
Any help would be really appreciated, Thanks
The crash flight occurred roughly 22.5 hours after the previous flight. I suspect the battery had performed a discharge.
I think the conventional wisdom is that it’s OK to fly on a non full battery if the flight takes place soon after the previous flight.
“battery had performed a discharge”
Meaning, the battery had started a auto discharge because of it settings?
I didn’t look at the log.
Rod…
Thanks for that Budwalker, Do you think the displayed 50% battery would then have been inaccurate? And the drop from 14.21v to 11.81v in .2 sec seems a bit weird to me due to no real change in throttle etc ?
Thanks RodPad, I have the discharge times set to max, 10 days I think it was. I think, If you press a button on the battery or use it, then that time starts again, eg another 10 days from the last use. But definitely something I did not think of.
Yes, that would be my guess. I didn’t see anything specific about an auto discharge. The sudden drop in indicated voltage matches the description of what happens when an auto discharge has happened. I suspect the initial indicated voltage comes from the last time the battery was on. In this case the actual voltage was 11.81v and the 14.21v comes from the last time the battery was on.
I know you KNOW this stuff!
I will be in the back ground!!
Rod…
Actually, I’m just guessing here.
And the drone displayed 50% battery so I thought I could sneak 5 min in for a quick pic. So it seems that a display delay was what tricked me? and lesson learned with regards to taking off with a less than full battery 
Thanks Very much for your advice people, This now makes me a bit more confident to fly it again once fixed 
@Ramjet1965, yes don’t do that!
I have made MANY other mistakes, but these forums help!
I always look for missing and crashes!
Because I have done them both and doesn’t make your day.
Rod…
Something would now like to add, The Crash log shows the Battery voltage at 11.76 in the player and the Temp was 62.5f
The temp would have been cold due to being camping and the drone was stored in the vehicle over night which was pretty cool.
I ran the Drone today with the same battery, still not charged since the crash and strapped to a couple of chairs for about 5 minutes, The voltage did not drop below 12.686 and is at 36% now but the batteries temp was 96.7f and the drone did not cut out.
I have looked at dozens of logs of my flights in AirData spanning 8 ish years and the battery temps were never below 89f at take off, and rose to as much as 137f during flight. Most of the flights would have had a near full charge at take off though.
The discharge was set at 5 days in the app when I checked and it was only 3 days since charge.
I don’t doubt that this was user error, “Not taking off with a charged battery”, but the battery still provides enough voltage with No top up charge to keep the drone going for way longer than the crash flight did but with the battery Warm.
I know that Lithium batteries optimal operating temp is approx 60f to 95f so my 62f was at the lower end and would account for higher volt drop in those few seconds of relatively cold flight and seems to reflect in the log.
I think that Low Temp was possibly the tipping (Crashing) point in this case.
What do you think to that theory?
It’s possible more could be learned by looking at the .DAT log file. Look here
https://datfile.net/DatCon/retrieve.html
to see how to retrieve it. To provide it you will need to use a public sharing site like Dropbox or GoogleDrive.