P3A went into auto land mode due to battery

[ggoosen]

Hi All,

wondering if anyone can provide some additional information on this.

The background info was that i was using my drone for fishing.

I was about to go out for a drop and only had +- 50% battery left. And thought i would do a quick drop.

I took off and while i was getting ready to attach my line to the drone, the drone have a battery warning error and landed directly where it was (luckily still on the beach)

Looking at my logs, the error was due to low battery voltage?

DJI Flight Log Viewer - PhantomHelp.com

Let me know if there is any other info i can share. I have the txt from myphone and the .dat from drone.

REgards

 

[tevek]

Apart from the usual 'don't fly with less than 100% battery voltage' which is completely valid, your % reading is generally an indictator (in my experience) of battery life/performance and not of cell condition. The data suggests that either your battery has some challenges and you need to put the unit through a full charge cycle and monitor its behaviour or you may have a battery the may have some issues. Not really enough info to make an assessment apart from flying with a partially charged battery.

 

[solentlife]

This is one of those 'silly moments' ...

I don't mean OP is silly ... please do not misunderstand me ... its a silly bit about battery and use in RC.

If you land but do not shut down ... a 50% battery would give you a second shot at limited flight as all the % battery references etc. still hold from when you put a fully charged pack in at start.

But if you fly .. power down and then power up again with that 50% pack ... you get a different result .. ie - possibility of not flying or an unexpected auto-land.

So ? Advice is not to try fly with a partial pack. Put a fresh charged pack in.

Nigel

 

[ggoosen]

Apart from the usual 'don't fly with less than 100% battery voltage' which is completely valid, your % reading is generally an indictator (in my experience) of battery life/performance and not of cell condition. The data suggests that either your battery has some challenges and you need to put the unit through a full charge cycle and monitor its behaviour or you may have a battery the may have some issues. Not really enough info to make an assessment apart from flying with a partially charged battery.

Worst part is i know these warning (guess i know first hand how serious they are)

If i make the digested .dat file available will that help with anything else?

 

[ggoosen]

This is one of those 'silly moments' ...

I don't mean OP is silly ... please do not misunderstand me ... its a silly bit about battery and use in RC.

If you land but do not shut down ... a 50% battery would give you a second shot at limited flight as all the % battery references etc. still hold from when you put a fully charged pack in at start.

But if you fly .. power down and then power up again with that 50% pack ... you get a different result .. ie - possibility of not flying or an unexpected auto-land.

So ? Advice is not to try fly with a partial pack. Put a fresh charged pack in.

Nigel

This is actually a very good point and completely plausible.

I'll take it into consideration.

 

[tevek]

Worst part is i know these warning (guess i know first hand how serious they are)

If i make the digested .dat file available will that help with anything else?

I would be inclined to charge the battery up to 100% and note the fully charged cell voltages (via the app) and give it a run close by. This forum is littered with partially charged batteries ending with tragedy and your event may be a one off. The file you previously attached should be indicative of flying with a partially charged battery with all the characteristics of powering up, throttling up and manoeuvring with the ambient conditions and getting the result a battery in that charged condition will deliver.

 

[Meta4]

Worst part is i know these warning (guess i know first hand how serious they are)
If i make the digested .dat file available will that help with anything else?

The .dat file won't show anything else that's important.
The Phantomhelp log shows that your battery was down to 3.3V per cell during takeoff.
Anything less than 3.3V and your Phantom isn't flying anywhere.
When you fly with a partially duscharged battery, the % indicator is giving you a false reading.
It's the voltage that's important, and your battery couldn't deliver the volts right from the start.

 

[solentlife]

In the old days ..... ESC's used to control motors from batterys would take the initial voltage as 100% and the Low Voltage Cutoff was based on a % calculation NOT the actual detected voltage.

This meant that LVC set at 3.3V would only operate at 3.3V if the LiPo / battery source was 100% at start. If you started with a LiPo at say 50% level ... or say 3.8V instead of 4.2V .... the LVC would activate at too low a voltage ... lets say for arguments sake 2.7V. Later development of ESC's recognised this fundamental fault and designed them so that the actual detected voltage was used and therefore 3.3V or whatever setting User put was the LVC and not a % of initial. This revolutionised standard RC flying and allowed us to then put a partial LiPo in for a quickie flight ... knowing our LVC was not compromised.
Strange thing is that NiMh / NiCd if set on the ESC still generally uses % ....

This makes me wonder if the amendment was not implemented in DJI gear or whether its really a FW issue. Either would produce the problem.

Anyway - the solution is like we used to do - only use FULL charged packs !!

Nigel

 

[ggoosen]

Thanks for all the comments.

Now my problem is actually the way I'm using my drone.

As I use it to case I generally only fly for around 5-10mins which uses about 15-20% of the battery. Becuase I have 2 batteries I am constantly charging theses batteries.

Is this ok? Ie drain The battery about 20% and charge multiple times a day.

 

[solentlife]

Of course keeping batterys topped up at max continuously is not good - but if you are using them that frequently - then its unavoidable.

What you could do - is get more batterys ... number them ... and cycle them in use so they have idle storage time ...

My average use is flight maybe every 2 days ... with 1 or 2 batts used. I have 3 batts ... so I try to cycle them in use.

I like to storage mine at the lower end of charge value - about 30 - 35% ... because I know I will be using the battery maybe 4 - 5 days later.

Nigel

 

[ggoosen]

Of course keeping batterys topped up at max continuously is not good - but if you are using them that frequently - then its unavoidable.

What you could do - is get more batterys ... number them ... and cycle them in use so they have idle storage time ...

My average use is flight maybe every 2 days ... with 1 or 2 batts used. I have 3 batts ... so I try to cycle them in use.

I like to storage mine at the lower end of charge value - about 30 - 35% ... because I know I will be using the battery maybe 4 - 5 days later.

Nigel

Thanks Nigel, I do have 2 batteries currently and cycle them. However with a fishing trip drops would occur every 1 hour for a few days. (2 normally)

Meaning i am cycling batteries about 6 time a day at least (12 drops)

 

[solentlife]

Interesting ... I would love to see your setup for fishing ...

I assume you are not fishing every day ? If not then I don't see a problem.

Nigel

 

[Technical Bob]

What are you low warnings etc set for the battery, some are preset around the 30% mark, so it may be worth dropping these to give a little more head room, so it doesnt set off back or auto land when the battery reaches 30%, but say 22%.

 

[solentlife]

P3A / P3P at 30% low battery warning should not auto-land ... it gives Verbal and Screen warning so that you know you better 'get on home' !!

Auto landing kicks in a bit later and until it gets in the low teens remains somewhat controllable. Personally I don't like getting that low - but it happens. Reportedly kicks in at Critical battery point, but that I have seen is not strictly true - I have had it above that point.

Page 13 / 14 of manual.

Of course one of the factors that can make this all strange .... if you are within 20m of Home Point and battery level drops to initiate RTH - it will actually auto-land instead ... why ? Because you are now within the GPS limitation of 20m radius for RTH.

Also manual says that if the battery level is only sufficient to land and not to RTH - auto-land will kick in.

Nigel

 

[RunningWithScissors]

Thanks Nigel, I do have 2 batteries currently and cycle them. However with a fishing trip drops would occur every 1 hour for a few days. (2 normally)

Meaning i am cycling batteries about 6 time a day at least (12 drops)

Forgive me for overstating the obvious, but I didn't see it mentioned in this thread. If you're cycling them that much, have you given any serious thought to buying one or two new batteries? Just my two cents.

 

[RunningWithScissors]

My apologies to solentlife for overlooking his earlier recommendation for additional batteries.

 

[Brother Dave]

Discussions like this are what make this site so valuable and important. I learn something every time I read through the posts.

 

[RunningWithScissors]

Discussions like this are what make this site so valuable and important. I learn something every time I read through the posts.

Truer words were never spoken.

 

[rodgerbwg]

Hi All,

wondering if anyone can provide some additional information on this.

The background info was that i was using my drone for fishing.

I was about to go out for a drop and only had +- 50% battery left. And thought i would do a quick drop.

I took off and while i was getting ready to attach my line to the drone, the drone have a battery warning error and landed directly where it was (luckily still on the beach)

Looking at my logs, the error was due to low battery voltage?

DJI Flight Log Viewer - PhantomHelp.com

Let me know if there is any other info i can share. I have the txt from myphone and the .dat from drone.

REgards

Go into your battery settings and set your low battery warning to 30% and critical to 17%. Before you do that see where they are now. What most likely happened is the you were close to your critical setting and it did an auto land due to a critical low battery level. When the battery is getting low it drops pretty quick. I have mine set to 30 and 17% and when I run my batteries down at the end of a flight what happened to you is what happens to me. When I get my low battery at 30% I bring it back to my landing area and then circle to discharge the battery. Also you use more power taking off than flying.

 

[Texas Gonzo]

Yup, its amazing how fast batts go from 30% to 15 or 10... certainly much faster than from 50 to 30!

I prefer to use a $20 dollar rig called a "rod and reel" instead of a $500+ drone for fishing... but I can accurately cast. While I hate to say it, I can't help but laugh everytime I read about someone losing their expensive drone when doing stuff like that with it. Atleast put some floaties on it. I can't see how all that prop noise wouldn't run the fish off to start with. But, to each their own I suppose. Fish ON!!!