Mavic Crash - Battery issues, refuses to land.

[DroneForceOne]

Hi guys,

Few minutes ago i just crashed my mavic from a heigh of about 2m.

I was flying over a park, and the battery reached about 25%. just started my return, slow wind, easy return. When it was getting close to my position, i noted that the Mavic had a slow descent speed, about 0.2-0.3 m/s. The stick down command was not bringing down the bird. Tryied the land button, also no results.

I tried a spiral descent maneuver, and got a dsc speed of 2-3m/s, but when i reached about 2m from the ground, the battery timer reaching 4m39s left, suddenly downed to 1m59s, warning sounding, and the drone refusing to go down.

It was at 1m50s of battery left or smth, i moved under the drone, so i could try to catch it (already specting the worst). So, in a matter of seconds: engines died, it went down. I touched it but was not able to avoid the crash.

The mavic was equipped with a landing gear extensors, gimbal cover and propeller guards, wich i think avoided a bigger disaster.

Got some minor cosmetic damage and a cracked led.

So, collected the drone and the accessories that were trhew apart, and removed the battery.

Took a charged one, plugged in, turned the drone on, gimbal check ok, engine test ok, checked all drone status, all seemed ok. Started engines, all running. Took off, drone flying, tryed some maneuvers at low altitude, drone responsive and flying.

But later, analysing the battery used on that incident, i noted that it was a little swollen compared to the others i have from my fly more kit.

Here are some pics i took just after it "landed".

Do you guys can help me with:

1- Why the drone did not responded the go down command.

2- Why the battery got swollen like that

3- is this a case for claiming any warranty service?

Thank for any help.

P.s.: Any comments like: "you were so dumb, why you did that", and things like that are not welcome.

 

[msinger]

Why the drone did not responded the go down command

Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.

 

[DroneForceOne]

DJI Flight Log Viewer - PhantomHelp.com

Thanks @msinger for the help, u rock.

 

[Oingo Boingo]

Quick question.... Don't ever store your batteries fully charged ?

 

[DroneForceOne]

Check out your TXT flight log to see if it explains what happened. You can upload and view it online here. If you'd like other people to review and comment on your flight log, then please post a link back here after you upload it.

Noticed that the message FORCED LANDING appears in midflight, didn't saw that while flying. Any guess?

 

[DroneForceOne]

Quick question.... Don't ever store your batteries fully charged ?

Hmm, no, i always charge them prior for flying, usually because i always expire them in the previous flight, and keep them discharged. Sure not my habit to keep them charged...

 

[Youser]

How long have you had the battery in question?

 

[ZaratustrA]

my guess for not responding to landing command: rear extender put wrong blocking the sonar.

 

[DroneForceOne]

How long have you had the battery in question?

Since i have the Mavic, about 6 months or so.

 

[DroneForceOne]

my guess for not responding to landing command: rear extender put wrong blocking the sonar.

I'm not that stupid, i sure i know how to place it, but thanks anyway for the hipotesis

 

[Cslucas34]

I'm not that stupid, i sure i know how to place it, but thanks anyway for the hipotesis

It may not be an issue of being placed wrong. It could be an issue of either design and or calibration. If memory serves me correctly, those sensors can be calibrated like the front ones. I had to redo my calibration for my front sensors after I updated the firmware.

 

[Cslucas34]

As for the battery, LiPo batteries are finicky things and have a very specific voltage range and current draw. Have you ever charged your batteries with an alternate source? IE in a car? Or how long have you had that battery / how many charge cycles?

 

[DroneForceOne]

As for the battery, LiPo batteries are finicky things and have a very specific voltage range and current draw. Have you ever charged your batteries with an alternate source? IE in a car? Or how long have you had that battery / how many charge cycles?

Never did any calibration for the landing gear extensors.

About the batteries, 6 months with me, no more than 12 or 15 flights, never charged in any other device that not DJI original charger.

 

[Cslucas34]

Never did any calibration for the landing gear extensors.

About the batteries, 6 months with me, no more than 12 or 15 flights, never charged in any other device that not DJI original charger.

Well for the battery; I would recommend trying to return it as it sounds like you may have a bad battery or getting ready to go bad. They should last around 500 charge cycles (albeit with diminishing returns). As for the landing issue I would try without the landing extenders or see about calibration with DJI assistant. You might be able to tell during calibration if those extenders are blocking anything. I’m not 100 percent sure on the calibration bit, just a hypothesis and that would be the first thing I would check if it were me. I suspect it has to do with the landing gear as well. My two cents.

 

[DroneForceOne]

Well for the battery; I would recommend trying to return it as it sounds like you may have a bad battery or getting ready to go bad. They should last around 500 charge cycles (albeit with diminishing returns). As for the landing issue I would try without the landing extenders or see about calibration with DJI assistant. You might be able to tell during calibration if those extenders are blocking anything. I’m not 100 percent sure on the calibration bit, just a hypothesis and that would be the first thing I would check if it were me. I suspect it has to do with the landing gear as well. My two cents.

Checking that, thanks for the tip!

 

[DroneForceOne]

After a more complete check up, found that this bracket that limits the gimbal movement has broken as well.

 

[Cslucas34]

After reviewing your flight logs, you will notice your VPS altitude is zero or nearly zero for most of your flight so that makes me think the system was refusing to land because the VPS and “safe landing” functions were preventing it. When you hit critical low point on your voltage it looks like that system turned itself off. Sorry to hear about your troubles, hope you get it all figured out and squared away.

 

[DroneForceOne]

After reviewing your flight logs, you will notice your VPS altitude is zero or nearly zero for most of your flight so that makes me think the system was refusing to land because the VPS and “safe landing” functions were preventing it. When you hit critical low point on your voltage it looks like that system turned itself off. Sorry to hear about your troubles, hope you get it all figured out and squared away.

Sorry, im quite noob on the terms, what is VPS?

I think the little bird will be ok. Minor damage only. But before taking off again i want to know what happened, so i dont make it wrong again...

 

[Cslucas34]

It’s ok. That’s why we are all here, to support each other. VPS means Visual Positioning System. It’s that little camera type object / sensor in between your landing extenders on the bottom. That system helps keep the drone stable hover / landing / etc. I found a video for that calibration I was talking about here is the link:

 

[Kilrah]

VPS = the downwards looking caneras and ultrasonic sensors that sense height above ground and horizontal movement at low altitudes. They were visibly disturbed and always thinking you were already on the ground preventing futher descent becaue you likely had the "landing protection" setting on. Most likely due to that landing gear that several have previously warned not to use, if you put one (unnecesary in most cases) you want one that extends out the back and leaves all the sensors perfectly clear.

The swollen battery is due to the severe overdistcharge that resulted from the aircraft waiting for an opportunity to land that never came, and is now good for the trash.

People really use too many poorly designed acessories on this poor Mavic.