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  • January 16, 2019, 12:26:01 PM

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Author Topic: Electric CL in the rain  (Read 369 times)

Offline Dave Edwards

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Electric CL in the rain
« on: January 12, 2019, 09:08:29 AM »
Does anyone have experience with electric CL flying in the rain? Our combat stuff is starting to get pretty good and will probably start flying at more and contests.  Inevitably, we fly in light rain and on wet days in general.  So far, I havent pushed the equipment on wet days and was wondering if anyone had experience with it.  Can anyone suggest which of the parts are most likely to have problems - to me it seems the timers would be most susceptible (but they can be buried in the wing and dont need cooling). ESC's are my next concern as they usually need air cooling. I am less worried about motors and batteries.


Offline Motorman

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Re: Electric CL in the rain
« Reply #1 on: January 12, 2019, 09:25:06 AM »
Total explosion of all components.
There will be a sunny day and we will fly our airplanes.

Offline Jim Mynes

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Re: Electric CL in the rain
« Reply #2 on: January 12, 2019, 12:48:10 PM »
Iíve flown in the rain a handful of times, only had a problem once. I believe water got into the switch connector on the timer and created a closed circuit when it should have been open (KR timer on a profile). After drying out everything worked as before.
I had put a rag over the nose of the plane, but it had rained pretty hard so I think the water just pounded through.
I will carry a non-permeable cover in the future.
I have seen the light, and itís powered by a lipo.

Offline John Rist

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Re: Electric CL in the rain
« Reply #3 on: January 12, 2019, 04:23:04 PM »
I would think the Electronic Speed Controller are the most in danger.  It has high power FETs switching huge amounts of current.  There are several in each ESC and they are switched on and off in a orderly manner to generate the AC current that drives the motor.  They operate in a digital mode.  That is to say they are hard on (very low resistance), or hard off (no current flow).  Good FETs have fast switching times (off to on & on to off).  As the FET is transitioning it has high resistance and therefore is heating up.  If the transition is fast the heating time is short and little heat is generated.  When moisture gets into the ESC it can bias these FETs partially on. The results is massive heat and smoke.

I would think the boating world has water proof ESC.  I am not sure if they are too heavy or if they have the features you want.

You are right the timer needs little cooling and can be protected.

Motors should stand some wet.  However moisture could cause shorts and smoke.  Once again what do boats run?

LiPo batteries are a problem. Moisture can cause shorts and smoke.  Once again, again what do the boats use.

In my youth I raced RC boats. But it was brushed motors, NiCads, and DC speed controllers.  Nicads were safe in water.  Motors didn't seem to care. We had water proof speed controllers.  We put the radio receiver in a water proof box.
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Online Tim Wescott

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Re: Electric CL in the rain
« Reply #4 on: January 12, 2019, 04:43:19 PM »
When moisture gets into the ESC it can bias these FETs partially on...

Not if they're using decent gate drivers.  The gate driver chips have quite low impedance outputs, to make the gates change voltage rapidly.  Even when you're intentionally slowing them down with series resistance, you're only using 50 or 100 ohm resistors.

I suspect that with well-designed components, the biggest problem is going to be corrosion over time.  So you'll be OK the first few times things get wet, but over time the metals on the board will corrode into a salt that's conductive when moist.

Manufacturers can alleviate this problem by painting the boards with something called "conformal coat" ("Humidiseal" is the one brand name I know -- it's extremely stinky stuff).  With conformal coat and thorough drying any time things get wet the electronics would last forever.  I have no clue what manufacturers actually do, although maybe some of our timer manufacturers could chime in.

I've been hoping that someone who competes in some electric RC event would chime in -- it has to be an issue any time you're playing with aircraft or even cars in the rain.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline John Rist

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Re: Electric CL in the rain
« Reply #5 on: January 12, 2019, 06:07:36 PM »
Not if they're using decent gate drivers.  The gate driver chips have quite low impedance outputs, to make the gates change voltage rapidly.  Even when you're intentionally slowing them down with series resistance, you're only using 50 or 100 ohm resistors.


True, but if you have contaminates on the board you can get leakage currents between FET leads.  It dose all depend on how well the mfg CO cleans the boards and if they coat them or not.  In my youth I designed and worked with military electronics.  And yes we built bullet proof electronics, but you wouldn't like the price.  All I am saying is that the ESC handles large amounts of current. If anything upsets the timing, or anything else you get smoke.  Water in your ESC is a bad thing.
John Rist
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Offline Igor Burger

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Re: Electric CL in the rain
« Reply #6 on: January 13, 2019, 01:31:16 AM »
Rain is distilled water, so basically insulator, but still, it can be contaminated and can transfer small current, so it can do something on base of "signals".

Motors are not problem at all, they will run in water without problem.

The danger thing is switch of any kind. I like positive switches - if shortened, model will finish flight, danger comes at next battery connection, if shortened, model will beep and that is sign switch is on. However I have switch exposed and I never found it "on" because of water.

ESC was already commented by Tim, I fully agree. I am not sure which manufacturer impregnates them, I can speak for Jeti, SPINS for C/L have 3 layers. and I know other Czech maker also covers them, so I hope it is standard on every "normal" (means not extremely cheap) ESCs. Covered is only PCB, so not cables and not capacitors. Anyway, it is not good to have water inside, so I seal the shrink tube with silicone on front side (at motor leads), so that the back side is open - it can breath and if some water is anyway in, it can evaporate. In case of combat I will seal both sides.

Timers (PCB, cables, switches, connectors) are usually not sealed, because they can be closed inside fuselage. So it is good practice to close them in waterproof coverage.

Battery will also not suffer from water in short time, but remember, there are aluminum leads, they will corrodate in humid condition, and that is problem for all those parts especially motor. It is not very funny to see rusty iron stator  ;D

Offline Dave Edwards

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Re: Electric CL in the rain
« Reply #7 on: January 13, 2019, 08:40:07 AM »
Thanks for all the comments, very helpful.  As I burn thru equipment, I will let you know what I find!  Hopefully I can find a balance between ruggedness, reliability, cost and weight that makes sense.

Offline Silver Dart

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Re: Electric CL in the rain
« Reply #8 on: January 13, 2019, 06:04:43 PM »
Not a problem, check this out

Paul Emmerson
Spinning electrons in circles in Mississauga, Ontario, Canada

Offline John Rist

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Re: Electric CL in the rain
« Reply #9 on: January 13, 2019, 11:34:39 PM »
Just watched the video.  Really good information. Back in my boating days we used Shoe Goo (clear) to seal things.  It is better than silicone sealer because silicone is corrosive.  Shoo Goo should work better than the epoxy for sealing the shrink tubing on a speed controller.  It is flexible.  I am guessing that it will stick to the silicone insulated wired.
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Offline Dave Edwards

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Re: Electric CL in the rain
« Reply #10 on: January 14, 2019, 05:36:34 PM »
Wow, looks like this is a very solvable problem! Never would have guessed that you could just toss the setup in the water like that.


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