troubleshooting drone dead drop MPP

Hello,

I have a Mavic Pro Platinum refurbish. Has been great for about a year, crashed a handful of times, nothing serious just broken props. I am trying to troubleshoot for a bad arm or motor, but i can not seem to find the motor current or rpm in the logs, or even during live flight. I uploaded the flight log from the crash here DJI Flight Log Viewer - PhantomHelp.com It is suggested if i can see the current or rotor speed i can see which motor is having trouble and go from there.

Details:
Drop happened February i was flying, it was around 40deg f with moderate wind. the drone was giving lots and lots of errors, i cleared them and they stopped so i figured it was warming up still. Flew for a while, and then got motor obstructed error, i was hovering around 8ft up trying to read the app to troubleshoot and it full stop and dropped. Broken front leg, i replaced and it has been flying fine but still gets the motor current error some times, never again the obstructed error. Props have not been changed since crash, they all look clean, smooth and good. I removed and re attached them and the motors spin smooth and easily.

You will need the .dat file for that. It looks like FLY144.dat. Motor speeds and current are not logged in the .txt file.

Ok i think i understand, i see the 144 file number in there, i uploaded it from the controller here 22-02-09-11-11-09_FLY144.DAT - Google Drive. please let me know if it will not let you access it.

It looks like you have two motor issues… Here are the values you asked about.

MOTOR SPEED

MOTOR CURRENT

I am new to reading these but tell me if i am on the right path.

So what i am seeing is on the current graph the left front motor continuously increasing current, that tells me the speed controller is bad, because as it warms up it is getting less efficient until it hit a point it just reset. It could be the motor but i would guess that it would have been more up and down overall, that curve more resembles a heat cycle.

On the rpm image the lines are moving together however the front two are slightly higher but stay consistent. this could be cheap props or the front two just naturally work harder due to weight distribution? But i see a blip at the 42.263 mark where left front and right back both shot up but the rest stayed steady. I wonder why because they are opposite corners. Maybe if front left crapped and the flight computer left front right and rear left solid to keep elevation static and then used rear right to roll and pitch to compensate?

overall the surges could be explained by wind gusts, they are inconsistent and for the most part all 4 motors surge together which would indicate the whole unit is surging in power at the same time.

Here is a new .dat file, i just flew it, tried to keep it in one spot, mild wind, off the back porch and it did come with come motor current errors but did not shut off after running for about 15 min.

I then landed and then took back off and tried to run it in sport mode really hard, ending in many vertical up/down without other input so the esc should be well in to operating temp. Would you be able to get the same current and rpm reports for this flight?

One thing i noticed was when shutting off rotors the front left stopped first, almost immediately when it landed it stopped while the others spun down normally. still the motor spins easily just like the other 3.

I really appreciate getting help with these .dat file.

You might also want to take a look at the ESC temps. The front ESC temps are running about 25 C cooler than the back temps.

I would have expected the just left front to be different. Typically, the temps run within 5 C. Here are the temps from my MP.

How interesting. So for my problem it looks like I have 2 solutions, replace the esc/flight computer board or the motor or both, or just scrap the MPP and get a new one. (this is now 3 generations ago)

But for the sake of the mental exercise and because i see lots of people with the motor current issue and without these charts it is really impossible to troubleshoot. It would be nice to come to some conclusions about these charts.

BudWalker the chart you made for esc temps is that from the crash log or the test log i just did?

I am trying to find a more detailed photo of the flight computer/esc. The layout may help, because i assume the 4 esc’s are laid out in pairs so one will heat up the second one.

One thing that does not correlate, if the front left is drawing more current and that was the reason for the shut down, but the rear esc’s are over temp that does not seem right.

So for others to troubleshoot, if the rotors are in good shape, and the motors spin freely and all 4 feel the same you are 50/50 that the motors are ok. Typically when a motor is failing either the bearings are bad or the windings have too much resistance either way the motor will draw extra power to try to keep up to speed. The motors are about $25 from ifixit and seem reasonable to replace without lots of skill.

The next step would be to pull flight logs and look at the charts to see if one of the waves is +/- about 10% from the others. Either way reading and understanding these charts is difficult and the flight computer board is a single non serviceable unit so you might as well just replace it. I have seen these boards for 100-250$ and they require a more detailed teardown and soldering. so depending on your skill set.

For my time, once we pulled the logs and saw the front left was definitely problematic, i should have replaced it just to see if that worked. I have spend more than $25 worth of time trying to read these charts and using everyone else’s time too. If the problem persisted it is either the flight computer or sending to dji to be refurbished or buying a whole new one because even with the flight computer there could still be other issues such as a bad main capacitor so there is bad power, or a bad battery pack which would also require further work and time.

In answer for Bud. Here are both for you.


This is also curious. Look at the Left Front And Right back voltage vs current. These show zero.

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Good catch

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