How can I review how my batteries operated during a flight ??

[Moose1967]

I do apologize if this was already covered but I can't find an exact post on this subject.

I am reading about drones that fall out of the sky and the culprit is a bad cell - well that's what the evidence points towards.

So can someone post the procedure (step by step) for me to fly with each of my batteries (I have three and a Mavic Pro) and then look at the battery logs and see how each cell is during flight.

I am a pilot that does the pre flight check list etc but I am also the pilot that wants to avoid issues if I can. I have never had a crash and hoping to avoid it at all cost through regular maintenance of the drone and batteries. I also don't usually drain my batteries below 50 percent - maybe the odd time - also don't use sport mode unless I am fighting the wind. So I have been real good to my three batteries with about 30 flights on each.

Much appreciated.

Thanks

Moose1967

 

[Keule]

then look at the battery logs and see how each cell is during flight.

An easy solution is getting an Airdata.com account and sync your logs with them.
You will see detailed information about your batteries.

Edit: Here what it's look like:

 

[Former Member]

An easy solution is getting an Airdata.com account and sync your logs with them.
You will see detailed information about your batteries.

Edit: Here what it's look like:

View attachment 73116

View attachment 73117

View attachment 73118

I second the motion.

 

[tcope]

I would also turn on the battery voltage within the DJI Go app and use this to monitor voltage during flight (and not just percentage of battery).

 

[msinger]

Since there's no telling when a battery cell is going to fail, it would be best to do as @tcope suggested. That'll allow you to see the lowest battery cell voltage in DJI GO at all times and take the necessary measures if you notice something doesn't seem right mid-flight. You can find that setting in the following section of DJI GO:




Another thing you could do is set the C1 or C2 button to "Battery Info". That'll allow you to quickly pop open the Aircraft Battery section of DJI GO and see the status of each individual battery cell.

 

[Former Member]

Common sense prevails.

If your battery is too hot to the touch, it needs to be monitored.

If your battery is puffed, stop using it.

If your battery has been in a crash, it will make a great paperweight.

 

[Moose1967]

Common sense prevails.

If your battery is too hot to the touch, it needs to be monitored.

If your battery is puffed, stop using it.

If your battery has been in a crash, it will make a great paperweight.

thunderdrone you are missing my point - outside of everything you mention you hear about some that fall from the sky due to a bad battery cell that’s may not be apparent from the things you mention - hence the post !

 

[Former Member]

thunderdrone you are missing my point - outside of everything you mention you hear about some that fall from the sky due to a bad battery cell that’s may not be apparent from the things you mention - hence the post !

Yes, but based on my experience working on thousands of crashed drones, I have found that in almost every single case, a drone fell from the sky due to an unlatched battery, bird strike, or simply colliding with something and losing the battle.

A battery with a bad cell will not cause a drone to fall from the sky. It will make the battery drain faster, but then when the combined voltage of all 3 cells reaches critical level, RTH will will take over and land the drone immediately. If one cell is lower than the others, the other 2 cells will try harder to make up the voltage difference needed to keep the bird airborne.

Lets start on the ground. If you have a bad cell, it is most likely you will get a battery error before you even spool the motors up. The 2 cells combined might not give you enough volts to satisfy DJI Go 4 that you have enough battery to take off. If you are able to get airborne with a low cell, every time you give it throttle, you will get a battery overdischarge error message. Thats a warning sign.

If you are lucky (or unlucky enough) to get a distance away, and that one cell is creating a huge drain on the existing 2 good cells, the battery temperature will increase, but that wont necessarily make the drone crash. The built-in low voltage cutoff will create a RTH situation. The drone will attempt to land itself based on the estimated remaining flight times the algorithm the remaining mah and voltage is providing to the flight controller.

Lets say, on the ground, one cell is 2.0 volts (legally dead) and the other 2 are 4.2 volts. 2+4.2+4.2=10.4 volts. That is enough for a climb out, but might not be sufficient for sustained flight, especially if it is windy or you are fighting a head wind. 10.4 volts could possibly give you a few minutes flight time before the drone forces itself to land. 10.4/3 = 3.5 volts average per cell

3.2 volts per cell or aggregate 9.56 volts would represent maybe 13% battery.

Long story short, you will know by error message, or by substantially reduced flight time, when a battery is getting ready to give up the ghost.

Technical geniuses, please feel free to correct my theory and assumptions.

 

[Moose1967]

Thx thunderdrone - so maybe I am thinking this out too much - sometimes on here I will see a post where graphs are showing battery cells separately - one cell beings lower than the two others possibly causing the drone to fail - this is what I mean - doing some kind of graph like that to eliminate the use of that battery or only use that battery for tweaking things in pre flight etc - kinda like a battery cell check - but if the djigo4 app will give you a warning I have never gotten any - all three of my batteries have 25-30 flights - they never get stored in cold areas always at room temp - I rarely fly them less than 40-50 percent - store them around 55 percent battery and I always let them cool down before charging again.

 

[Meta4]

I am reading about drones that fall out of the sky and the culprit is a bad cell - well that's what the evidence points towards.

sometimes on here I will see a post where graphs are showing battery cells separately - one cell beings lower than the two others possibly causing the drone to fail

I think you've got your wires crossed.
I read a lot of flight data and see a lot of fall-from-the-sky incident data.
I can't remember seeing any that were due to a bad cell.
It's quite normal for the cell voltages to differ slightly without there being a problem.

If you really want to see what's going on with your cell voltages during a flight, you can't do much better than to look at your flight record with the Phantomhelp log viewer.

DJI Flight Log Viewer | Phantom Help

Upload and view flight logs from your DJI drones

www.phantomhelp.com

That will show you what's going on in each cell for every 1/10th of a second of a flight.

 

[Moose1967]

Meta4 here is a graph of what I mean:

Repair Invoice.......... REALLY?????

September 2018. Flying over ocean in Oregon, battery at 42% suddenly 0% battery in a millisecond, force landing alert and MA lands in two feet of saltwater and sand. Used my DJI refresh and had a brand new MA sent with replacement battery. Even though this was NOT pilot error, as I needed the...

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