UPDATE: RPM only spreadsheet: https://drive.google.com/file/d/1AlqKE8W0fRsTYwPrgUGsmLXVMFXlcH1U/view?usp=sharing  Thanks to Sean for this.

Hello, I have a very new Mavic Mini. I tried to fly for a few minutes today in no wind conditions and I did not even go high. Below 5m. Upon launch, the aircraft swayed a bit but stabilized but immediately a propeller spinning too fast error throws up. I land the aircraft and the left rear motor was beeping. I restarted the aircraft and tried again. Nothing this time. I tried three more flights from same area and hovered. It swayed a bit around 2m from the ground sometimes to left sometimes to right  but I moved the craft higher and it hovered more or less fine.

I am a new pilot so unsure if it was a fluke. Here's what I did differently during that flight. I had a very small sticker on top of the aircraft that had my contact details. I launched it from the mavic mini (non flymore) box and it swayed immediately on launch. I removed both of these things during the launch after that.

Flight logs txt I was able to retrieve from phone

The flight before the issue (was 2 days back) : DJIFlightRecord_2020-11-07_[11-33-48]  https://drive.google.com/file/d/1KD75qcSxK-WB_kNe2Ii4qjnHKo39rGsk/view?usp=sharing
The flight during the issue : DJIFlightRecord_2020-11-09_[13-11-18]  https://drive.google.com/file/d/1a8J0VigdaK4nVd2jlmTHP8yO6Nd7QyGW/view?usp=sharing

Three flights after restarting where the errors weren't shown: https://drive.google.com/drive/folders/18bxcsOGCJh89fgUG9ekZYzWoU_C3Bpgu?usp=sharing

Logs from MCFlightRecords but I am confused what is what. I had data sync on so it might not have all the info.

Here's the log from the aircraft SD Card- https://drive.google.com/file/d/1FZcKO37Tk7UKT2H138oifSaoZXNex_xO/view?usp=sharing  (again, the time of issue is 2020-11-09 13:11:18 flight start time)

I am a newbie, please point me to right direction. Thanks.

If by MCFlightRecords you meant MCDatFlightRecords,  the MCDatFlightRecords folder is in the FlightRecord folder where you found the .txt logs. You are looking for a file with a name like 2020-11-09-13-xx-yy_FLY034.DAT or 20-11-09-13-xx-yy_FLY034.DAT, I get both forms of the date year for some reason.

I have had a quick skim through the log from the mSD card and it, as expected, seems to cover a number of flights, there are 113,700 odd lines in the file lol. (If you pm me an email address I will send you the csv and spread sheets of the log).

The left rear and to some extent the right front motors consistantly report higher speeds as shown in the attached.


I am guessing the 2nd set of data represent %'s
To me this suggests that at least the props of the left rear need changing.

However I have not looked at how the drone was being flown in these logs, others are MUCH better at that than me.
What I would say is you need to do a check flight.
Indoors start the motors and take off using the automated buttons, hover for a minute or so and then land using the automated buttons. DO NOT TOUCH THE JOYSTICKS DURING ANY THIS FLIGHT. Then post the flight's DAT file.


If your MCDatFlightRecords folder is currently empty I would switch off sync, wifi and mobile data (belt and braces approach lol) before you fly this check filght and leave them off until you have a copy of the DAT file saved somewhere safe elsewhere.
If your MCDatFlightRecords folder is currently empty and it is thought by others that syncing erases the DAT files you might try emailing DJI and asking for a copy of the DAT file, |I have read that they will in some cases send one, whether that is true remains to be seen.

Hello there nilanganray. I am sorry to read and to know about this issue on your DJI Mavic Mini and thank you for reaching out. Did you receive any error message on the DJI Fly application? To ensure a safe and enjoyable flying experience with your DJI Mavic MIni, DJI have added a new safety notification feature on the DJI Mavic Mini in the latest v01.00.0500 firmware. This feature lets customers know when propellers need to be inspected or replaced. In addition, I will post an official DJI thread with regards to this matter. Thank you.

https://forum.dji.com/thread-214705-1-1.html

Sean-newbie Posted at 11-9 02:11
If by MCFlightRecords you meant MCDatFlightRecords,  the MCDatFlightRecords folder is in the FlightRecord folder where you found the .txt logs. You are looking for a file with a name like 2020-11-09-13-xx-yy_FLY034.DAT or 20-11-09-13-xx-yy_FLY034.DAT, I get both forms of the date year for some reason.

I have had a quick skim through the log from the mSD card and it, as expected, seems to cover a number of flights, there are 113,700 odd lines in the file lol. (If you pm me an email address I will send you the csv and spread sheets of the log).

Thank you Sean for a great detailed reply and helping me out. I am not sure if I completely understand all you have said.

I have some questions. Does the SD card log have entries since day 1? I would be keen to know what the LBack speed is for flights 10 days back. That would give an idea. My drone is around 15 days old.

Also, I had another question. Not sure if it is possible for you to answer it. Is the prop speed same during my flight that showed the error (11-09 1:11pm) and the ones where no error showed i.e the one I had two days back and the 3 flights I had after this error where no error showed.


Another thing. I do not recall this correctly but I think I read somewhere that the Mini has one of the rear sides spin faster than the other ones because of weight distribution. Not sure how to confirm it.

Finally, I am wondering if it is okay to do your indoor test outside if I am sure there is no wind. Thing is I am not confident flying indoors and have tight spaces.

FINALLY, THANKS AGAIN AND I AM PMing YOU MY EMAIL ID FOR THE CSV.

EDIT- THis is the thread where many users talk about having higher motor speed in rear left prop - https://forum.dji.com/thread-214705-1-1.html For the record, I do not have the Flymore combo carry case that many users seem to suspect.

Re "Does the SD card log have entries since day 1?"  I have no idea, ignoring GPS dates in 2015 I see dates form 28/10/2020 but bear in mind the size of the file and that I could have missed some. At a guess fc_log.log contains samples from some logs.
The incident flight .txt log points to the 34th DAT file and the DAT files are numbered/named sequentially but the counter resets to either 0 or 1 at 99 + 1. Their recording starts at drone switch on and stops at drone switch off.

I haven't trawled through the data to check the number of dates.

Re question two, "I had another question. Not su....." at the moment I haven't looked that closely at the data.

I believe the weight distibution and speed thing to be correct BUT, if so, it applies equally to all 4 motors, so both rear motors should turn slightly faster than the fronts. But, and assuming you were not having it do acrobatics, 12000rpm vs 8000 rpm etc. is not good.
Bear in mind that any maneuvers you make are caused by speed changes in appropriate motors and you can perhaps see the reason for the joystick commandless check flight.

The mini flies very well indoors and the wander once hovering seems to be less than 10cm, however there may be an initial take-off-and-climb drift of up to 1m or so but, believe me, the room where I normally fly it is a tidy person's nightmare of nightmares.

Could you do the test outside? yes but be sure there is no wind.

Sean-newbie Posted at 11-9 03:19
Re "Does the SD card log have entries since day 1?"  I have no idea, ignoring GPS dates in 2015 I see dates form 28/10/2020 but bear in mind the size of the file and that I could have missed some. At a guess fc_log.log contains samples from some logs.
The incident flight .txt log points to the 34th DAT file and the DAT files are numbered/named sequentially but the counter resets to either 0 or 1 at 99 + 1. Their recording starts at drone switch on and stops at drone switch off.

Thanks. Could you email me the data? I would like to inspect myself to see if I can find data from older flights and compare it.  I have PMd you my id.

Sean has been of great help. He provided me a sheet with motor data only.  After seeing the data, I am more confused as some flights  have higher RPM on LFront while some have higher on Rback, etc. Although today's seem to indicate that the Rback is speeding. But today's data does seem most problematic with Lback going as high as 14k with others below  10k. Although it did stay in 12k range for the most part.  

Different from my flight 2 days back. I can't seem to realize what might have went wrong. I see no damage at all in Rear left props and both today and 2 days back I only flew around 10m for a few minutes. I would do a hover test as Sean suggested and also change the props few days later to see if there is any changes.  

Meanwhile if someone wants to take a look at RPM only data, check here: https://drive.google.com/file/d/1AlqKE8W0fRsTYwPrgUGsmLXVMFXlcH1U/view?usp=sharing

Without knowing the command inputs and the wind conditions at those times citing specific readings is not really helpful, besides which you appear to have sorted the data by the speed of the left back motor which distorts the impression given. I think I sent the data sorted by the GPS time stamp.
This is why the hover test is strongly suggested. Besides, if you switch sync and wifi etc. off you should end up with a DAT file for the test flight and then CsvView can generate charts, which are often easier to interpret than numeric tables.

CsvView does not seem able to generate a motor speed chart for the fc_log.log file, though it did produce the csv file I sent.
The speed only spreadsheet was meant for you to get a general impression and because of its 'minimal' file size, the impression I got was that the left back was generally the fastest motor and quite often significantly so.
BTW you should now have access to the full spread sheet, 450Mb or so

Sean-still-learning Posted at 11-9 09:45
Without knowing the command inputs and the wind conditions at those times citing specific readings is not really helpful, besides which you appear to have sorted the data by the speed of the left back motor which distorts the impression given. I think I sent the data sorted by the GPS time stamp.
This is why the hover test is strongly suggested. Besides, if you switch sync and wifi etc. off you should end up with a DAT file for the test flight and then CsvView can generate charts, which are often easier to interpret than numeric tables.

Thanks. I will do the hover test you recommended in optimal conditions and get back to you.

I had a quick question. Sometimes I notice that the hover is not as stable near the ground as it is like 2-3 meter above ground. Is this because the wind from the props hit the ground and nearby objects and then push the drone a bit?

"Is this because the wind from the props hit the ground a.... " I think so but I also suspect that the VPS is sensitive enough to pick up objects below the drone that are flapping in the downdraft. Some of the twitches I have seen from mine seemed to be synchronised with flapping cloth or paper etc

Hiya,

read your post and the reactions on that.

I have a MM 1, never had an high rpm over speed warning in all my flights.
Just picked 3 random flights and see the RPM data.

Left Rear motor is always spinning but faster than the Right rear motor. (hover. no wind. no inputs, or flying forward with no cross wind)

If your warning is just once and all flights after that no warnings...do not worrie about this isolated high rpm warning.(ofcourse always check rotor blades as part of your pre-flight check for cracks, damage etc etc)

As said by Sean ; do a hover in house (so no wind, no rc inputs), and share that flightlog and DAT file (both on your mobile device).

cheers
JJB

JJB* Posted at 11-9 12:14
Hiya,

read your post and the reactions on that.

Sean-still-learning Posted at 11-9 11:12
"Is this because the wind from the props hit the ground a.... " I think so but I also suspect that the VPS is sensitive enough to pick up objects below the drone that are flapping in the downdraft. Some of the twitches I have seen from mine seemed to be synchronised with flapping cloth or paper etc

Hi,

I have done the test as you suggested.

Here is what I did.  Autoland hover for a minute or two. Then autoland.  Then I manually took off again and flew a bit here and there.  Extremely negligible wind really.


https://drive.google.com/file/d/1_WxzPXa4hq18eRYC2PrP0NNKyXv5vNWP/view?usp=sharing


CC: @JJB*

fans2825b6e8 Posted at 11-9 23:48
Hi,

I have done the test as you suggested.

Hiya,

Will compare your rpm with a test of my MM today, first look into you data is that left rear is indeed higher than i would expect from normal higher.

But no errors in flight so within limits ofcourse.  Always great to have a spare set of blades, so mayby change the rear with spares and do the test again.

cheers
JJB

JJB* Posted at 11-10 00:06
Hiya,

Will compare your rpm with a test of my MM today, first look into you data is that left rear is indeed higher than i would expect from normal higher.

I did another test flight and checked myself with csvview. It does look like LBack and RFront are acting unusual. I know I need to change the RFront and LBack at least. I hit myself with RBack and it has visible scuffs but the data looks fine. I would change regardless though.



Not sure what the deal is with LBack because it is very new and I see no visual damage.

fans2825b6e8 Posted at 11-10 00:40
I did another test flight and checked myself with csvview. It does look like LBack and RFront are acting unusual. I know I need to change the RFront and LBack at least. I hit myself with RBack and it has visible scuffs but the data looks fine. I would change regardless though.

[view_image]

Hi,

Just performed a hover check on my own MM in my house, see the chart.
Recently changed all 8 blades, due to some damage to one (better safe tan sorry ; so changed all 8 blades with orgininal DJI ones)

4 motors close to each other, so my conclusion is to change your props and see how your rpms will look like with new blades

cheers
JJB

The problem with the faulty blades is most likely warpage or distortion which changes either or both the 'aerofoil' profile and its angle of attack. It need not be nicks, cuts, scrapes or cracks. The problem is I think caused by the storage positions and this particulairly affects the rear props.
Due to the cant of the motors the rear blades have to be bent/depressed to intermesh with one another when they are positioned across the body. The front motors are not so canted so the necessary bending is not so severe.
My mini, which was new, arrived with flatten rear blades and I got two pair (4 blades) from DJI under warranty. Right from the outset I subsequently stored it, in the flymore case, with the rear props pointng forwards under the gimbal cover, only their tips are intermeshed and no bending is required. The front blades are positioned over their respective arms with foam blocks being used to 'locate' them

Nilanganray wrote: "Not sure what the deal is with LBack because it is very new and I see no visual damage."

The propeller blade distortion can be very subtle and difficult to spot with merely a visual inspection.  It is not only FlyMore Combo Minis that suffer from this.  Even the standard non-FlyMore Minis show the same distortion, particularly of the left-rear blades, due to the way the Mini is packed and shipped with the blades crossed.

Please have a read through this other thread.  It started out as a discussion about prop holders, i.e. aftermarket devices securing the props to keep them from flopping around loose when stored.  DJI ships the Mini with cheap paper bands securing the blades.  But as you'll see when reading the thread, it is storing the Mini with blades crossed that's causing the blades to deform and lose lift.  Even some brand new (non-flymore) Minis straight out of the box already have the rear blades deformed.

The most reliable measure of propeller blade performance is the hover test.  In a stable hover with new propeller blades, all four motors should be spinning at equal speed of approximately 9600 rpm.  If you prefer to do the test outdoors, be aware that any wind will affect the result.  If the Mini has to lean into the wind to hold position, the motors on the high side will spin at a higher speed.  To determine if wind actually is influencing your results, just repeat the hover test with the Mini turned at all four compass directions, North, East, South, West.


mavicpilots.com/threads/propeller-guards.99882/

Have safe flights!

Hello I changed all the props with original props except Lfront (which was fine from day 1).

I still have same problem with Left Back spinning faster than others with it staying around 11k-11;5k range on hover only and goes as far up as 14.5k while flying up.

Here's hover only data-

Here's some flying left right and top up to 62m altitude-

Is this hover test an automated take off?
I would be inclined to swap L.back and R.front props and see what happens, just be sure to keep the blades in their original pairings. Have you added anything to the drone that would add weight to that that the L.back has to carry?
One other suggestion, set the mini on a table etc. start the motors and let them idle for maybe 20 to 30 seconds, enough time to give a reasonable trace. Maybe even try this with all the blades removed. I am not sure if it will tell anyone anything but ....

Sean-bumble-bee Posted at 11-20 02:58
Is this hover test an automated take off?
I would be inclined to swap L.back and R.front props and see what happens, just be sure to keep the blades in their original pairings. Have you added anything to the drone that would add weight to that that the L.back has to carry?
One other suggestion, set the mini on a table etc. start the motors and let them idle for maybe 20 to 30 seconds, enough time to give a reasonable trace. Maybe even try this with all the blades removed. I am not sure if it will tell anyone anything but ....

Hi like I was saying, I replaced Lback, Rfront, and Rback with new props and continue to have same thing. I am unsure if this is a concern or not because I only bought this drone less than a month back. I haven't added anything to the drone.

I am aware that you swapped  3 propellors sets but with the suggested swap you check whether the reported speed is associated with the blades that are currently on the left rear motor. If it is then presumably the RF might show a high speed and the LR  speed would be reduced compared to the others etc.etc.

Sean-bumble-bee Posted at 11-20 03:16
I am aware that you swapped  3 propellors sets but with the suggested swap you check whether the reported speed is associated with the blades that are currently on the left rear motor. If it is then presumably the RF might show a high speed and the LR  speed would be reduced compared to the others etc.etc.

Sorry but I dont understand you correctly. I had this data with the factory propellers and now I have the same data after replacing both LBack and RFront with brand new propellers. I fail to see how swapping them would make the difference unless you are suggesting that the LBack setup/motor itself is somehow damaging/deforming the props and making them spin a bit faster.

Why dont you just try what is suggested and report the results?
You have new props fitted but they are to some extent an unknown quantity, you need to eliminate uncertainties other wise you remain guessing.
The suggested swap would put a seemingly good pair of blades on the LR motor and a possibly defective pair ( though the chance of that is slim) on a good motor RF.  If the RF subsequently has to turn faster and the LR rotates more slowly then it suggests that the blades currently on the LR are defective. (slim though that chance maybe)
The suggested idle and or propless idles are, perhaps, methods of seeing if there is a reporting error.

Indoor hover

Is that after swapping the props between the LR and RF? If so then there is something else going on. The question is what and you need someone with more knowledge than me to help you.

Problem solved?

Attached are two plots for a  2nd hand MM I have just bought. When I opened the case I thought the rear props had been badly stored in the case with the left rear particularily bent and its crescent profile flattened so the first flight was a hover test, as shown, along with a table top idle.
The second chart is a hand held idle and 'hover' test, with some very gentle maneuvering thrown in, using new props. This is what I would have expected to see ifyour had had deformed props and the new ones were good