Sudden voltage drop

[psl_air]

Flew the mavic mini the other day and experience this weird voltage drop. I didn't know about this until I looked at the flight record a couple of days later. I have three batteries and this happened with one of the new ones. They appear to charge up fine and I did not see any errors indicating battery issues. After landing, it did not shut down right away, the props stayed running for another 5 to 8 seconds after touchdown. Also, is there a way to pull up messages or error history that appear on screen during a flight? I did see other messages that popped up and then disappeared before I could really understand what they were about.

Start of flight.


Voltage drop start.

End of flight.

 

[Gagey52]

Welcome to the forum mate. Good questions I’ve had a number of error messages come up only to have the disappear before you can read them. I’m sure someone here will have an answer.
Regards

 

[Deleted member 103366]

You might be able to see error messages if you replay the flight on or in the flight records section of "profile" or "me " accessed via the front page of the app.

 

[psl_air]

I was looking at the flight record a little closer and I noticed that the voltage shown in the record did not change for a good amount of the flight. It shows it changing at first then it gets locked on one voltage and then when you see the voltage drop in the images above it starts to show the lower voltage. The percentage portion of the record seems to be correct in that it shows a constant drop throughout the flight. I'm wondering if it's just the way the recorder is playing back the record. Or, maybe there's in error in the way the mavic interprets the data

 

[Deleted member 103366]

I assume that the above tables come from a webpage, if correct and if you have no objection to making the data public can you post the URL for that webpage on here? There may be graphical ways of displaying the data that are perhaps easier to read than tables.

 

[psl_air]

I assume that the above tables come from a webpage, if correct and if you have no objection to making the data public can you post the URL for that webpage on here? There may be graphical ways of displaying the data that are perhaps easier to read than tables.

Try this link Park

 

[Deleted member 103366]

That does look precipitous but over a small range.
But before you do anything drastic with the battery wait and see if one of the gurus weighs in. There was a serious battery behaviour discussion in here not long ago with what seems like some very good posts in it dealing with capacities and behaviours. I'm trying to find it
Attached is your plot vs one from a flight just flown that started with a not fully charged battery, your does seem very either horizontal or vertical with nothing in between, which seems odd. Oh the sudden drop in mine is probably idle vs flight

 

[psl_air]

That does look precipitous but over a small range.
But before you do anything drastic with the battery wait and see if one of the gurus weighs in. There was a serious battery behaviour discussion in here not long ago with what seems like some very good posts in it dealing with capacities and behaviours. I'm trying to find it
Attached is your plot vs one from a flight just flown that started with a not fully charged battery, your does seem very either horizontal or vertical with nothing in between, which seems odd. Oh the sudden drop in mine is probably idle vs flight

I'm using the galaxy S7 to run the app, I'm wondering if it could be a software issue or phone hardware issue that could be why the graph looks as it does. In my flight record it does not show the cell voltages until about 8 minutes into the flight but it shows battery voltage. Then right after that it starts showing the cell readouts that stay locked on about 3.7 volts per cell along with the Total battery voltage @ 7.465. The numbers stay locked to those values till about 16 minutes into the flight then show the sudden drop with the numbers again staying locked @ the lower numbers. The only battery values that look consistent are the battery drain percentages.

 

[Deleted member 103366]

I noticed the lack of early data and the break just before the dive but explaining that is beyond me, you need the gurus for that.
However, the battery in question here has serial number 1U5G0CF5Z05055 (see column JF, DETAILS.batterySn or 266 in the csv), and has, I think, only been charged twice (see column DG, CENTER BATTERY.loopNum or 111 in the csv) (The count goes up in steps of 256 I think). If you download CsvView and go through your other flight logs you could perhaps see how this battery behaved on a previous flight or flights.

 

[slup]

Don't think it's anything wrong with the battery itself ... looking at the total voltage reported out from the battery it's a slowly decreasing graph which voltage wise harmonize well with the estimated battery percentage. Have below placed the marker exactly at 50% & there the voltage is 7,29V = 3,65V/cell. It rather looks like the signal group CNTR_BATT doesn't behave ... can't say why though.

I would test this battery all the way through again, low & slow ... & see if the log again reports the individual cell voltage wrong. Also, if you have another battery ... do the same with that & compare.



Don't know if the crappy connection during most of the flight could have messed up the log reporting ..?

 

[psl_air]

Don't think it's anything wrong with the battery itself ... looking at the total voltage reported out from the battery it's a slowly decreasing graph which voltage wise harmonize well with the estimated battery percentage. Have below placed the marker exactly at 50% & there the voltage is 7,29V = 3,65V/cell. It rather looks like the signal group CNTR_BATT doesn't behave ... can't say why though.

I would test this battery all the way through again, low & slow ... & see if the log again reports the individual cell voltage wrong. Also, if you have another battery ... do the same with that & compare.

View attachment 122706

Don't know if the crappy connection during most of the flight could have messed up the log reporting ..?

View attachment 122707

That's an incredible amount of information, So nice to have the ability to retrieve the error logs. I Do have a large antenna system at the park I go to. I'm not sure what it's purpose is but I would imagine it could create a good amount of interference at some level. Not sure. I will monitor each battery closely as well as try different flying locations and see how it works out. Thank you for the information.