Waterproofing with Silicone Fire-Retardant Waterproofing

[broloch]

Hi Spherers,

I picked up a canister of Silicone Fire-Retardant waterproofing spray, do you think it is a good idea to spray this over the inside parts of my controller for waterproofing purposes?

 

[broloch]

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[Zoot Katz]

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All I learned is that conformal coating is good.
It's better if it's removable.
Leave the box open 24 hrs after application to allow all the solvents to evaporate.
IOW, don't spray instant magic into an opening and hope for the best.
Read the data sheet for the product to be sure it's going to do what you require.

 

[broloch]

I know you have a lot of knowledge about ebikes, but do you know a lot about fire retardants as well?

Are they any good?

 

[Ypedal]

when electronics go up in smoke, it's usually a short lived event ( dead short ) .. that being said, there is little need for a fire retardant.. waterproofing however is important if you ride in the wet..

Sealing water out 100% is nearly impossible, sometimes water gets trapped in and canot evaporate and dry up, allowing rust to form ..

routing wires so water drips down away from the enclosed areas is a good idea..

I've drowned the controller on my norco a few times to the point it just quit running.. let it sit a few days and it goes again ! ( incredible this thing still runs !!!! it's a 6fet unit, bumped up to 35 amps by soldering the shunt, run at 90v !!!! 4th year in service !!! )

my eZee bike is a submarine, the controller is completely potted, filled with rubbery material.. i ride this bike when they forcast rain, last thrusday was the test, i rode home 7 kms in pissing rain, aiming for every water hole i could find... never skipped a beat !

 

[broloch]

Even if it rains, why pedal, right?

Wow, eZee sounds terrific. I saw a pic of some gentleman running the controller under a tap.

 

[broloch]

Is it possible to run an eZee controller with a Crystalyte hub?

 

[Anonymous]

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[ElectricEd]

If it's acetic curing then don't. The vapour causes corrosion of tracks and connections on the pcb. It must be a neutral curing material. NutsandVolts is correct, in my experience trying to waterproof electronic enclosures in a food production area where I work, any attempts to make an enclosure waterproof just makes it a great container for attracting and retaining water. After trying everything including silicon bead satchels without success, I drilled a 1.5mm drain hole at the lowest point of one of the enclosures. After comparing the enclosures after 2 weeks, all of the enclosures had water slopping around in them except the one with the drain hole. Now every enclusure has a drain hole.
You can get grommetts designed especially for this that allow water to drain out but are resistant to water entry. I'm pretty sure that RS and Farnell have them.

 

[broloch]

I didn't try potting or sealing anything.

I ended up using silicone conformal coating for electronics, and sprayed the insides of the controller.

 

[zukster]

I didn't try potting or sealing anything.

I ended up using silicone conformal coating for electronics, and sprayed the insides of the controller.

How did that work? I'm looking at potting or an alternative for ecrazyman controllers up here in the Lower Rain Land.
Also known as Vancouver Area, BC, Canada. It is very wet right now.

edit: Justin from ebikes.ca just recommended doing this for an Infineon(ecrazyman) when I asked him about what
kind of potting compound to use.

 

[broloch]

sorry brah, i couldn't really tell you. i wrecked my controller when i was making a secure and lockable mount for it.

one cable came loose and when i tried to reattach the cable, the controller sparked, this was due to the conformal spray

in theory, it should work, only you must not completely seal the controller and must allow drainage

 

[zukster]

when i tried to reattach the cable, the controller sparked, this was due to the conformal spray
in theory, it should work, only you must not completely seal the controller and must allow drainage

Man that sucks. I don't think it would have sparked because of the coating though. Something else
must have happened too. I just finished wiring up another bike yesterday. Sensorless 36V Ecrazyman.

Last step was

cross fingers
plug in battery pack
flip on on switch
jump back just in case

If you get the board well coated. I assume top and bottom, it should not be a problem if the case has
drainage or not - IMO. I think the main thing is to STILL USE the case as there are a lot of solder runs
built up and attached to the case from the board though screws to the case for cooling. It would be so
so so so small without the case that the controler would fit under the seat - but I have to resist. Maybe
if it was potted with thremal material this would work. Hummm

 

[zukster]

After a couple of more year at this, I can vouch for the small hole at the lowest point.

Or another trick is simply mount the controller with the wires down and this allows any trapped
water to seep out along the wire channels.

I only had success with one controller with the wires leaving upward, and this was a monumental
effort of Silicon RTV sealant on the closing plates and wires leaving the controller. If I really
wanted 100% waterproof, next time I would just pot them.

So far wires down is working.

 

[biohazardman]

I agree with mount the controller with wires pointed down. One may also want to see that it is out of the weather the best you can. My controller is mounted under the seat with wires on the bottom and is only in the weather when I am riding. Other than the way I mounted it I have taken no action to waterproof it. It rains plenty here and I have had no problems with the controller or the motor which I simply made sure the wires had a loop lower than the axle before they went into the motor. I don't pay much attention to the weather when I ride. That's the parking lot of a boat launch and park near the Columbia river. It rained a bit so river is up 20Ft or better from the norm. The whole boat launch area is under several feet of water.

 

[Kingfish]

My one concern with conformal coating is that some parts rely on radiation to operate. The power resistors for instance, will become even hotter, and certainly any FET surface would need to be masked off. Why not just coat the end-plates instead? And I wouldn’t use silicone for that as it is hydroscopic; use instead polyurethane – a whisker-thin layer at the mating surface. The flexi-material used to pass wires through could also be treated. Polyurethane cures to tough in two hours, and is completely cured within 24 hours indoors if it’s not applied thickly.

Just as a side note: I would make/allow a tiny vent hole at the lowest end so that any moisture that does find a way inside will also be able to drain out. :wink:

My ½ watt, KF