Thank you for taking the trouble to test this out for us

Not looking forward to that!

Thank you for posting that.  It is VERY informative.  Not the damage so much, but the way the battery and board are laid out in the housing, and the PC board.  On the board, you can easily pick out the LEDs and power button, the cell balancing lines, main high current lines, etc.  

As for the damage, it is obviously extensive.  I am going to guess that this battery was in the salt water for the mentioned 5 minutes or more, but no immediate steps taken to minimize the damage once it was recovered.  Chances are, damage would have happened anyway, since it was salt water, but it may not have been as extensive.  I'm pretty sure I have read of some that were dumped into salt water and survived, but they were recovered quickly and taken care of.  Fresh water dunking are well documented in this forum and are not rare.

That looks bad....

AG0N-Gary Posted at 2018-3-11 13:18
Thank you for posting that.  It is VERY informative.  Not the damage so much, but the way the battery and board are laid out in the housing, and the PC board.  On the board, you can easily pick out the LEDs and power button, the cell balancing lines, main high current lines, etc.  

As for the damage, it is obviously extensive.  I am going to guess that this battery was in the salt water for the mentioned 5 minutes or more, but no immediate steps taken to minimize the damage once it was recovered.  Chances are, damage would have happened anyway, since it was salt water, but it may not have been as extensive.  I'm pretty sure I have read of some that were dumped into salt water and survived, but they were recovered quickly and taken care of.  Fresh water dunking are well documented in this forum and are not rare.

After about 45 minutes I placed everything, including the battery in distilled water but the battery was already making sounds and heating up after a quick bath of salt water.

The drone does not seem as bad inside, but I am still drying it.

After you dry out the drone my advise is to get acetone and give all electrical parts and connections a good cleaning. Any moisture will cause corrosion, even if you can't see it at first.
If the Drone does come back to life and is flyable my last step would be to coat the boards with a clear coat.

For that battery, you are lucky that it didn't go "Boom"

Good luck with the cleaning.

Seems wild that in 5 minutes, water seeped into every nook & cranny of that battery & caused that damage...hope the drone is still flyable!

Wow I always wondered what the inside looks like. Hope your drone survived.

B1houdini Posted at 2018-3-11 14:27
After you dry out the drone my advise is to get acetone and give all electrical parts and connections a good cleaning. Any moisture will cause corrosion, even if you can't see it at first.
If the Drone does come back to life and is flyable my last step would be to coat the boards with a clear coat.

I would be very careful with Acetone.  I have seen it eat up plastic, and once start working on a circuit board.

In case of beer, coke, coffee soaked electronics, best way I have found to clean them is with repeated rinsing with regular water, then distilled water.  Followed by blow drying.  
Lastly drying by low heat source, like 20-degrees warmer than surrounding air.

"If the Drone does come back to life and is flyable my last step would be to coat the boards with a clear coat."

After seeing above pictured battery damage, and fact battery got hot.  

DJI should seal internal battery packs, and clear coat all internal circuit boards.
Even without a dip in ocean or lake, or accidental drenching from pool splashes, there is always sudden rain.

B1houdini Posted at 2018-3-11 14:27
After you dry out the drone my advise is to get acetone and give all electrical parts and connections a good cleaning. Any moisture will cause corrosion, even if you can't see it at first.
If the Drone does come back to life and is flyable my last step would be to coat the boards with a clear coat.

Be careful with the acetone, as it may melt the plastic. It would be better to get a good electrical contact cleaner. Hope you getting it flying again.

Is better to use isopropyl alcohol to clean up.

Don't use acetone. It will melt the plastic.
Rinse with lots of fresh water making sure you get a good blast under the IC's then rinse with distilled, then isopropyl alcahol. Blow dry the boards with compressed air(and probably repeat the wash rinse process) then as others have mentioned dry in a warm place. Even a hot air gun(if the boards are removed from the housing) will be good to use, but be sensible about it as it can get hot enough to melt the solder. You will need to get the moisture out of the actual board.

Good luck with it.

I don't know why DJI don't use a conformal coating on their circuit boards. They make a really good product, but forget to finish it!

Lipo's and water, especially sea water, do not mix! Thanks for posting.

Mavdude Posted at 2018-3-13 22:43
Don't use acetone. It will melt the plastic.
Rinse with lots of fresh water making sure you get a good blast under the IC's then rinse with distilled, then isopropyl alcahol. Blow dry the boards with compressed air(and probably repeat the wash rinse process) then as others have mentioned dry in a warm place. Even a hot air gun(if the boards are removed from the housing) will be good to use, but be sensible about it as it can get hot enough to melt the solder. You will need to get the moisture out of the actual board.

With all the  answers "don't you acetone" . They are right about it can melt plastic. I don't believe any circuits boards are made of plastic. Some of the cheaper components are made from a type of plastic  but acetone has such a fast evaporation cycle it should not affect them if you are careful.
I worked in the Avionics field for 30 years and acetone was the preferred cleaning agent for us. In the early years we used Toluene which cleaned 100% better but turned out to be to harmful to people.
Alcohol works well if there is not much corrosion or contamination.
Of course the problem could of been avoided to some extent if the boards were coated with some sort of protective coating.
The acetone use was only my recommendation. What ever you decide to use, do it with caution and be safe.




   

Thanks for sharing... electronics and water dont mix

yikes - thanks for posting - interesting to see. did your battery cells swell up too or are they ok, hope you resurrect your drone

i've posted this before,  but this is an amazing video of a Mavic that spent a week underwater -- and lived!

It wasn't salt water, but still an amazing story.

Ouch that hurts! What happened?

I'm surprised that folks were trying to figure a way to save that battery.  Even if it appeared to be successful, I'd be afraid to use it versus just buying a new one.  I assume the battery was in the quad when it happened and not just dropped in by itself?  

Bekaru MP UAV Posted at 2018-3-14 09:02
yikes - thanks for posting - interesting to see. did your battery cells swell up too or are they ok, hope you resurrect your drone

The cells are OK. That is the only part in the whole drone who suffered.
I am thinking on maybe using the cells for a diy usb powerbank