Electronics got wet. ESC or motor broken? - RC Groups
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Jun 20, 2012, 04:12 PM
Registered User
Daniel S's Avatar

Electronics got wet. ESC or motor broken?


After a successfull maiden flight of my new Seawind EP I taxied too fast home in the choppy sea, the canopy flew off by digging into a wave and the plane filled with water. (I will tape the canopy in the future.)

After drying up - all servos are working, the ESC does all the right startup and arming beeps, but the motor (RimFire 400 outrunner brushless) only vibrates slightly when applying throttle.

The ESC got pretty wet, but the motor probably didn't get too much water splash.

I have no extra motor or ESC to test with.
Should I buy a new ESC, a new motor or both?
I'll get myself a multimeter later this week and run the motor with my drill, but can I rule out a broken ESC since it beeps ok?

Thanks in advance
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Jun 20, 2012, 04:57 PM
parkcityskier's Avatar
My experience has been that water will not damage a motor. I've even run them under water. However, your ESC symptoms sound like an ESC problem. I had one get dunked pretty bad and it wouldn't start the motor, like your problem. After a few days, however, I tried again and it worked. I would recommend you wait a few days before ordering a new ESC. If it still won't start the motor, try coating the ESC with some CorrosianX. Sometimes, this will work. In the future, soak your ESC and receiver in CorrosianX to prevent water damage. You can also do the same with servos but it can be hard to access the circuit board and usually just smearing some vasolene around the output shaft will be enough. I've never had a servo problem but have had several ESC problems before I started using the CorrosianX, and none after. Forget the bit with the drill. You may just damage the motor. Good luck.

I'll be in Stockholm this September. Beautiful country.
Last edited by parkcityskier; Jun 20, 2012 at 05:02 PM.
Jun 20, 2012, 05:12 PM
Slip the surly bonds...
Sopwith Mike's Avatar
I had this identical problem a fortnight ago - twice! After a few hours and blowing air through the motor it worked perfectly, and is still doing so. I managed to get the motor running on just an amp or so at first, but as you say, it joggled back and forth at more throttle. It took a while to run up, but did so in the end.

Keep trying, good luck

Jun 21, 2012, 03:49 PM
Registered User
Daniel S's Avatar
Hello again,

Thanks for your replies.

It's been a week since the incident now. Still same result. Perhaps waiting won't solve this.

The motor never starts, even on small throttle. It only vibrates, trying to move one step, never succeeding no matter how much throttle I give.
I have noticed that after 5-6 seconds of the ESC trying to start the motor, it shuts down the throttle signal to the motor and the motor stops vibrating. I have to throttle down and up again for it to start vibrating again. Seems like a function of the ESC.

I have heard a lot about this CorrosionX. Unfortunately it cannot be found in Sweden, but I have found something similar.

But while writing this post I thought I should give the ESC a layer of my corrosion protection to see if anything happens. It did. Smoke happened when connecting battery. I didn't wait long enough for it to evaporate before testing.

I have already ordered a new ESC. Probably won't get it until next week. Hopefully this will get the motor running. I'll get back with the results.

Jun 22, 2012, 08:52 AM
parkcityskier's Avatar
Sorry that the ESC wouldn't come to life for you. It is the weakest link in flying off of the water and can be easily destroyed by moisture. Check the forums on waterproofing ESCs. There are some different methods if you can't get CorrosianX. Whatever you use, give it a day to completely dry before you power up the ESC.
Jun 24, 2012, 09:35 PM
God of Gravity Poisoning
Arkansas Travelr's Avatar
Originally Posted by Daniel S
Hello again,

I have heard a lot about this CorrosionX. Unfortunately it cannot be found in Sweden, but I have found something similar.
It is sold in Denmark and Germany maybe you could buy some from a distributor there (a 16oz bottle will last for years). Here's a list of international distributors hopefully one of the EU distributors could help you.


Originally Posted by Daniel S
But while writing this post I thought I should give the ESC a layer of my corrosion protection to see if anything happens. It did. Smoke happened when connecting battery. I didn't wait long enough for it to evaporate before testing.
You don't have to worry about that with CorrosionX you could fire up you ESC totally immersed in C/X and everything would be fine.
Jun 27, 2012, 10:56 PM
60 years of RC flying
Daedalus66's Avatar
In four years of water flying I've lost 3 or 4 ESCs to dunking but never a motor, receiver, or battery. And I've seen several other ESCs fail in my friend's models.

Often, if you resist the temptation to open the throttle after the dunking, the ESC will survive. If you do try to apply power, the ESC will usually die, sometimes with obvious signs but often not.

The best protection against ESC destruction is CorrosionX. I now generally remove the heatshrink, douse everything in CX and let it drain for a few hours, then add fresh heatshrink. I have yet to have a treated ESC fail when dunked.

I should add that I had one crash when water got into the rudder servo via the cable exit and affected the pot.

With a wet receiver, I just remove the case and let it dry out really well, often in the sun for several hours or even a couple of days. I blow the water out of the motor and re-oil the bearings. Motors never seem to take any harm.
Jul 03, 2012, 01:14 PM
Registered User
Deadstick 8409's Avatar
I don't kow how effective it will be, but I sealed both ends of an ESC with hot melt glue. I can not imagine how water could possibly get in, unless the ESC gets too hot and softens the glue? Hopefully will never find out......
Jul 05, 2012, 02:49 PM
Registered User
Daniel S's Avatar
Hello again,

Finally - after much too long wait - I got round to test my new ESC. Everything works splendidly now!

I should probably try to order CorrosionX from Denmark. But I'm heading off to my seaside cabin this weekend and cant wait for any deliveries.
I'll have another try with my corrosion protection (waiting 24 hours this time) and redo the heatshrink.

I've heard you shouldn't seal the ends of an ESC, since it could get too hot. I think I'll try CorrosionX first.

Thanks for all the help.

I'll get back if (when) I get new problems.

/Daniel S
Jul 06, 2012, 10:00 PM
Registered User
va3mw's Avatar
I take all my water ESCs apart and coat them with Conformal coating. I've never had a problem with an ESC getting wet since.

This is one of the ones I use: http://www.mgchemicals.com/products/419c.html

Aug 03, 2012, 04:35 AM
Registered User
Flipped my EPO Minicub on floats over after take off yesterday and it stayed with the nose down until I came out to it after 30 seconds. When I lifted it I heard a "boiling" sound (just like a water boiler). Disconnected the lipo as quick as I could but it had already puffed. Gone!

I guess there had been a short circuit. Now to my questions. I supposed due to the short circuit, the esc had been fried but when I examined it, I could see no burnt parts. While laying in the water it was completely under water. Is there any chance it still is OK? I havn't dared to hook it up to see if it works, can any other component in the chain get destroyed if I try? The Rx didn't work at all, won't bind. Is there a chance it will recover after complete dry out.
Motor and servos seem OK.

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