Tweet
To increase the cure rate of most epoxies you need to heat the ESC and epoxy to 120 degrees F. A small cardboard box and a 75 watt light bulb will do the trick. Use a thermometer on the epoxy to keep under120 degrees or it will liquidise during cure. After cure (usually 12 hours) it will be good to about 150 degrees.
-
-
Something in the back of my head is SCREAMING that this doesnt work (I'm an organic chemist an work in a lab... I've played with alot of calcium carbonate.) But I can't put my figure on it.... I need to mull this over and get back to you, but its a great ideaComment
-
According to Polymer Composites, it's a formula that is used for exactly this purpose commercially. Resin type epoxy/mold/compound with higher levels of calcium carbonate to promote thermal conductivity. I'm curious what you might find. I haven't had the chance to question anyone directly with any hands on working knowledge of the process.FighterCatRacing Team CHING BLING - Ching Bling. Brilliant, Advanced Sparkle for your hull.Comment
-
I can do that. I have a warming plate. Thanks!
BTW- I just made bubble gum. Turns out that I only used about 60% of the amount of hardener that I should have. I walked through the formula and circled back and found my mistake.
The good news is that when heated, it just runs off of the ESC, so some tin foil and a bit of patience and it's time to make another batch.
It takes about 24 hours for the calcium carbonate to fully saturate the resin, so now the clock ticks. Hey who knows maybe tonight be in 3 days we arrange ship.
PS- I'm also adding a copper plate & tubing on this one. I'd actually like to use it. I'll try the metal less experiments on the cheapo ESC's.
As far as warranty on this ESC, it's already a gift from the junk box, so nothing to lose and everything to gain. =)FighterCatRacing Team CHING BLING - Ching Bling. Brilliant, Advanced Sparkle for your hull.Comment
-
Yes but I feel like there is a trick to it or something that needs to be done.... I still haven't found anything but I've just got a nagging feeling there's something.....
Synthesis of materials are very tricky as you probably know....Comment
-
And it's 50% less fat too!!! LOL I hope this works Fightercat, cause i tried to waterpoof mine and some how the saltwater got to it still and smoked it the other day...
Comment
-
Well, before epoxy sealing it, I would make sure to hit it with a conformal coating. Also note the motor wires, if exposed to salt water, could short out.
Also, the silicone wire jackets will deform and allow a gap between them and the epoxy. It may take several applications to fully seal the ESC for water proof use.FighterCatRacing Team CHING BLING - Ching Bling. Brilliant, Advanced Sparkle for your hull.Comment
-
First point I was going to make was check the mix ratio. Polyester uses a catalyst, so a little bit will still cause the chemical reaction to start, just takes longer to grow the molecules.
Epoxy is a hardener. Part A reacts with Part B, so you need the proper amounts.
As mentioned, heat will help it react. When I water cool my ESC's, I use room temp laminating resin and let it kick off. I then heat the oven until the temp starts reading that it is climbing, maybe 170ish? I then shut it off and THEN put in the coated ESC's. The oven holds the heat and warms the epoxy enough to accelerate the cure. works well, mine run underwater, but the largest is a 90/100.
The best I have seen is cooling in an electrically inert fluid. thier are fluids made just for this or there are oils that will work also. The oil will keep water off of the controller and flow around the ESC while conducting heat. An aluminum plate can act as a heat sink in the oil, or make the case from aluminum and have it mounted in the bottom of the boat. Used to do this on our scale RC combat ships to cool voltage regulators and warm the CO2 lines.
Did some work helping a grad student cool data acquisitions boards for a NASA research plane. the fluid definately cooled the boards well, but it is a fluid and has to be contained.
BrianComment
-
The problem with "waterproofing" is the flexible power and motor wires, which will move enough to break any seal and eventually allow water to wick inside. If solid posts are above the sealant and the wires are soldered to them, then it could work.
As far as thermal conductance, calcium carbonate (limestone) is not bad for a cheap, easily obtainable material with a thermal conductivity between 0.72 and 0.77 BTU/(ft hr *F). Even better is graphite, between 0.98 and 2.3 BTU/(ft hr *F) - higher is better. Nickel is even better at 52.6 BRU/(ft hr *F) but not a good idea for obvious reasons.
However, as stated in a post above convection is a far more efficient method of heat flux, and a solid does not convect. A blower fan is much much more effective at cooling as long as the cooling air doesn't get too hot. Go ahead and try it, but no maker of higher-end warranted ESCs will ever use it since it eliminates the possibility of inspection or repair.
.ERROR 403 - This is not the page you are looking for
Comment
-
Hahahaha if only you knew.... I've set several hoods on fire... the worse are the reactions where water causes it to react more.... What are the amounts you are using? I haven't noticed you list what parts for what... (IE 4 parts epoxy to 1 of the CC)Comment
-
Fluid, there is a waxing pre-process that allows removal of the resin cast, it's commonly used in encapsulating electronics for marine use. The resin cast and wax can be removed for circuit repair and then re-installed or re-casted.
Water proofing is best done with conformal coating prior to waxing and casting. Any wire jackets need to be bonded with the resin cast. If the materials don't bond, there will need to be additional sealant to bond them. Silicone typically seals these areas and bonds to both silicone and resin cast. Or like you stated, stripped and bonded directly to the wire.
Submersion in a "thermal oil" which is in direct contact with the heat source and cooling source of course would be the most efficient cooling method. This is exactly how home transformers are cooled outside your home.
Convection is also an excellent method of cooling. The problem being ambient air temp rising in a sealed compartment causes gradually increasing inefficiency. Perhaps negligible. Perhaps enough to prevent adequate cooling.
Combining these different approaches is perhaps the most effective, but perhaps least realistic.
What I would like to accomplish here is successfully water cool an ESC using thermal epoxy resins. It may not be the best or most effective, but may provide a low cost disposable solution for marine applications.
FighterCatRacing Team CHING BLING - Ching Bling. Brilliant, Advanced Sparkle for your hull.Comment
-
Someone had my exact idea, a waterproof box filled with thermally conducting oil, into which is placed the ESC. Wonder how long it takes to cool off. testing will tell. This method absolutely waterproofs the ESC as well as cools it.
-tComment
-
Sigh. Any idea of the thermal conductivity of a wax? Waxes are good insulators, with thermal conductivities typically under 0.25 BTU/(ft hr *F) and thus their use reduces the effectiveness of the whole concept by a considerable magnitude. Add the time needed to remove the mess at the warranty station and it just isn't a good idea for a manufacturer. But like I said, try it.Fluid, there is a waxing pre-process that allows removal of the resin cast, it's commonly used in encapsulating electronics for marine use. The resin cast and wax can be removed for circuit repair and then re-installed or re-casted.
Keeping an oil inside an ESC has the same problems as keeping water out, except oil usually wicks a lot easier. Transformers never move when in use, ESCs are constantly having their wires tugged on and bent. Who wants a gooey mess inside their boat? And the box makes the ESC that much larger and more awkward to install....
No need to guess, fans are a proven technology and work well for those who have bothered to use them. The larger the hull volume the better they work, and in some cases at least they work better than any water cooling. KISS is one of my main guiding principles with FE boats - reliability is important to me.
.ERROR 403 - This is not the page you are looking for
Comment
-
Aquacraft esc's. Fully waterproof. What do they use to seal it up?Comment
Comment