Mini Quad Crashed into the Ocean | Salt Water = Drone Killer

I was flying at this beautiful seaside spot a few days ago, but my quadcopter failsafe’d and fell into the water. This is a good case study and we can talk about what to do after getting the drone out of water.

I think I was flying too low and lost line of sight with the quad (blocked signal). Anyway I didn’t crash too far into the ocean, so when the tide was getting lower, I was lucky enough to find the quad. The GoPro Session 5 was proven more superior in this incident than the Runcam 3S for its water-resistance! It was in fact still recording when I picked up the quad.

The quad in the video – Flipmode.

Is the quad still working?

If you crashed in a river or lake (not salt water), it’s more likely to save the quad when retrieved fast enough. But salt water is much worse due to the corrosive nature, it’s extremely bad for electronics and can almost instantly destroy your quad (especially when powered on).

Unfortunately, my quad is nearly totally dead, except the FPV camera (Eagle 2, probably because of the fully enclosed camera case, and the water couldn’t get in). I also managed to salvage the motors, frame, buzzer, FPV antenna and props. But I probably have to change out the bearings on the motors as they feel a bit rusty now.

What salt water can do to your electronics (e.g. FC) in a few hours

I’ve seen quads survived after bathing in water, but it’s not uncommon that some components can be damaged so don’t get your hope up if this happens to you. Even if you managed to save the parts, you should test them rigorously before flying them again. Especially the RX and VTX, do range testing on them carefully.

It’s really a hit and miss. Maybe it’s not worth the effort saving those components after all because the corrosion doesn’t stop once it starts. After you think you have “fixed” it and the components that seem to be fine today, performance may degrade quickly, or even fail in a few days.

All the steel hardware (bolts, nuts) have gone rusty, but titanium and aluminium don’t seem to be affected.

What to do after mini quad submerged in water

Take it out of water and disconnect the battery ASAP!

Wash with Alcohol

Take everything apart, remove all the heatshrinks.

Wash electronics with high % rubbing alcohol (e.g. 99+% isopropyl alcohol) and a toothbrush to clean the residue/minerals and corrosion. Best to do this before it dries.

Rinse in Distilled Water

Put the parts in a bucket of fresh water (distilled if possible). It’s better to remove the lens from the camera to avoid getting water trapped in there that can cause fogging later on.

Let it Dry

To dry it, it’s best to rinse it with 99% alcohol, most of the water will evaporate within minutes. But if you don’t have alcohol, you’d want to leave it for a couple of days to dry, the longer the better. Some people prefer to put it in rice to speed up the process, but I think an hair dryer might be a better alternative. Also oil the motor bearings, or even replace them if they necessary.

Testing

Before powering on for the first time, check for short circuit with your multimeter. Use a “Smoke Stopper” if possible.

6 thoughts on “Mini Quad Crashed into the Ocean | Salt Water = Drone Killer

  1. Mark Pfeifer

    Glad you got your quad back! It would be interesting to see how to replace quad motor bearings (and how to know what bearings to get and where to get them).

    Reply
  2. Ghostface

    Check out Corrosion X – can even help if applied after a salt water bath.
    It is very good but also very messy so I just stick to conformal coating and not flying over salt water these days :D

    Reply
  3. Adhvik Chandran

    I crashed my quad in a dirty pond and had to get it out with a net, but after an hour of drying it worked pretty well!

    Reply
  4. Lorenzo

    Hello. My quad crashed in a swimming pool last year. It works almost better than before excep for the bearings. I can confirm that the distilled water method saved my quad. I rinsed it with a gallon of dist.water and then a 5 hours sunbath on a scorching july italian sun. Because i suspected that there was more moisture trapped inside i placed the quad in a bucket with lid and with two handfuls of dehydrating salts on the bottom of the bucket ( quad was suspended over salts with wires). The salts are avaliable and cheap from hardware stores. I found almost another half waterglass of moisture the morning after.
    Cheers
    Lorenzo

    Reply

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