HELP WANTED: DJI F550 Water landing, what should i do?

[dr3n3al]

Hello everyone, i need your help and advice.
flying my Hexacopter DJI F550 between two buildings, it wasnt windy where i was but 15 feet of the ground the hexa start shaking really bad, with strong wing, i lost visual and it landed on one of those ponds that new buildings are so fond of it. I know its all my fault, learned my lesson.
the lights were still on UNDER WATER
now, what do you recommend to clean it up and if possible make sure the electronics work.

what i have done:
>i took it out of the water and disconnect the battery
>i walked home and all the way here i hold it in a position that water was dripping.
>got home and opened up everything, disassemble everything and made sure i can dry things up in the shade
>I opened the NAZA M lite, all the screws and surprisinly inside it was only one drop of water which gives me hope
>i opened the futaba receiver and dry everything up with paper towel, gently
>i took the propellers out
>i disconnect all the ESC and they look dry
>i will let it dry for a couple of day before i reconnect everything and try it

so except for the solder parts, everything looks like a fresh kit
some people recommended me isopropil alcohol to clean up the electronics

anything else that i should do? any advice?
Thank you all

 

[RAM]

Pretty sure you are supposed to put it in dry rice for a couple of weeks. Adsorbs the moisture. Just don't cook it.

 

[Craftydan]

Give the motors a douse of WD-40 to drive the water out of them, dry, then oil the bearings with 3-n-1 oil (or oil of your choice).

for the Naza, RX, ESCs, and any other circuit boards, drop them in a container of dry rice to suck out any remaining moisture.

Before you power everything up, I'd check the RX and ESCs first with a current limiting source -- a damaged ESC can give unregulated power to the motors and smoke them instantly.

Easiest way to limit the current is putting a 12v automotive lightbulb in-line with the battery "+" wire. If you've got some bullet plugs handy should be easy to solder them on the bulb and plug in. The bulb should give the ESC and RX plenty of power to boot and link, but not enough to burn a motor out. Plug it in, and if the lightbuilb lights, unplug it and toss the ESC -- it was trying to burn out your motor. If the lightbulb stays dim, and the ESC goes through it's boot up chimes, it should be good.

Most everything else, just leave out to dry.

Good luck getting her back together . . . and try to stay dry next time

 

[Tactical Ex]

Your good so far, take it apart and put the components in rice (sealed bag) and leave it for a few days or maybe a few weeks. If this was salt water, throw your battery away and use alcohol and a microfiber cloth to clean EVERYTHING. Once you are done you should test out each part individually as much as possible to isolate any bad circuitry. If the lights were still on when you pulled it out of the water you might be OK. Just test, test, test and take it easy on the next few flights.

 

[dr3n3al]

Thank you everybody for your help, thanks God it was fresh water, as soon as i can test it i let you guys know
Thanks again

 

[dr3n3al]

i found this on another forum and gives me hope

"while on the subject of motors. I read somewhere that you should break in a motor in water... it gives the impression of submerging the motor in a cut of water....
Now I'm not electrical engineer, but something about shorting out positive and negative currents in water doesn't sound wise.
Whats the story behind this and how is it done? does the motor fill with water?
A:
It works because you only use 2 cells for break-in; at 3V, clean water doesn't carry enough current to short the motor.
Blow out the water with compressed air, hit the motor with a hair dryer on LOW for 5 minutes, lightly oil everything as stated above.
If it really worries you, spend a buck for a jug of distilled water. At 3V, it's an insulator...
A:
The reason you can use water is not only lowish voltage, but the fact that water does not naturally conduct electricity. Pure water is an excellent insulator, it only becomes conductive when impurities are added. In addition to that remember that electricity always takes the path of least resistance, when you have a motor underwater the path through the motor is easier to transverse than the path through the water. Thus you can run motors underwater with no problem... however I wouldn't try it on something like a 32 cell's and an F5B motor or anything "

I am not going to put them through water on purpose, but since it happened on fresh water, i think i have a good chance that everything will start working again, i will just wait a week before i reconnect everything

Thank you guys again for everything

 

[earthsciteach]

Give the motors a douse of WD-40 to drive the water out of them, dry, then oil the bearings with 3-n-1 oil (or oil of your choice).

for the Naza, RX, ESCs, and any other circuit boards, drop them in a container of dry rice to suck out any remaining moisture.

Before you power everything up, I'd check the RX and ESCs first with a current limiting source -- a damaged ESC can give unregulated power to the motors and smoke them instantly.

Easiest way to limit the current is putting a 12v automotive lightbulb in-line with the battery "+" wire. If you've got some bullet plugs handy should be easy to solder them on the bulb and plug in. The bulb should give the ESC and RX plenty of power to boot and link, but not enough to burn a motor out. Plug it in, and if the lightbuilb lights, unplug it and toss the ESC -- it was trying to burn out your motor. If the lightbulb stays dim, and the ESC goes through it's boot up chimes, it should be good.

Most everything else, just leave out to dry.

Good luck getting her back together . . . and try to stay dry next time

Dan! That automotive lightbulb thing is brilliant! Yeah, its a good pun, but I mean that sincerely. I'm glad I have you as my Keeper of Electron Knowledge.

 

[Craftydan]

Teach,

No problem! Learned that from flashing ESCs where things can go VERY wrong.

Dr3n3al,

The motors themselves are electrically insensitive to water . . . powered or not, they don't care:

BUT . . . they do rust. WD-40 is designed as a water displacer -- a chemical that drives water out of machinery. Give it a good spray and it should clear it all out.

Now WD-40 is not horrible as a lubricant but it's not great either, so I recommend following it up with a few drops of 3-n-1 oil (a popular machinist oil) to lube the bearings.

 

[stay-fun]

Break-in of motors in water is only useful for brused motors. This gives the brushes a nice fit the the stator (or whatever it's called) so it doesn't wear out as fast. Brushless motors do not require break-in. I'm guessing yours are brushless, so the only thing you need to worry about is bearings.

And yes, pure water doesn't conduct. Water with ions in it will, how much depends on the concentration of ions. "fresh" water is no indication at all how many ions the water contains I'm afraid... You'll find out if your electronics survived as soon as you plug the battery back in. The above idea with the light bulb is a good one!

Edit: that's some way to stir the coffee, Dan!

 

[dr3n3al]

update
>futaba receiver = tested, working without issues
i connected the receiver to a small battery and to a small servo, all works as the first day i got it

>3S LiPo 11.1v 3200mAh = tested
i conected the battery to a hobbyKing cellmeter7, all cells tested ok, 12v, no issues, at least that is what it shows

i dont want to burn the Naza, does anyone knows how to test it?
thanks guys

 

[Craftydan]

If it's all dry and the rest of the gear plugged into it tests out fine, the test for the naza is to plug it in -- it's either already dead or it's just fine.

 

[dr3n3al]

Update
I finally got around to do some soldering and made the test for the ESC according to Craftydan Specs, thank you Dan for all your advice


Then i hooked it up to the PDB on the Hexa



i got lucky, one out of six ESC is bad, so not a total lost
i tested the first four and i start thinking that the lightbulb was bad, then on ESC 5 when i connect the second motor bullet to the ESC it light up like a Christmas three, so i didn't even connect the third bullet, then the 6 ESC was OK too.

Thank you everybody for all your advice and your patience and your help, since there is no stores here in Chile carrying ESCs, well there is only one and very expensive, i will have to wait until my order gets here from China.

side note: i was looking for tools and things recommended in the forum for me, here in Chile I could not found anything in the proper places, WD-40 is everywhere no issues there, but the 3in1 oil was another thing, then when looking for the lightbulb to my surprise i found that in the cars section of some stores they carry everything from the states, is just hidden away in dark aisles, so i got 3in1, so i am set now

 

[dr3n3al]

since I had to disassemble the whole thing anyway, I took the opportunity to fix some other issue that I messed up at the beginning as a newbie, all connectors are now as we say "regulation" and I made sure to improve my soldering skills.
I also made a mount for the antenna receiver, and mount extras in a different way, a cleaner way, now i got more internal space to experiment.

all set and working, thank you everybody for your help