The end goal of this project was to give my friends jeep RGB underglow. It took 5 months, sometimes working as late as 11:30pm with flashlights, and when it was 26° and snowing. Now that we are finally almost done with this second iteration I figured it would be a good time to post about it.
The first iteration was relatively simple. Buy some waterproof LED strips, epoxy them under the jeep, run the wires to some switches in the cabin, and be done with it. This is pretty much exactly what we did.
We quickly realized that while this setup looked good at first, it was wholly inadequate. The LED strips were not actually waterproof, and had a common positive, so whenever they got wet (which was a lot, this was new england in January) they would faintly glow whatever color happened to be connected to the common by the water. Another smaller issue was that because we were switching grounds, there was no way to make the lights in the switches turn on. This first version lasted about two days before totally losing functionality and starting to smoke, so we disconnected it from the battery and decided to wait for warmer weather for the next version.
For the second iteration the three main issues we decided to focus on fixing were making the strips totally waterproof, only having the common positive connected when the strips were actually being used, and lastly making the lights on the switches in the cabin light up. We also decided to add some waterproof connectors and attach the strips with magnets so they could be taken off if needed.
To make the strips waterproof, we totally encased them in polyester resin. We started with some aluminum U channels, and added a spacer to get the strips right to the top of the channel for maximum light diffusion. Then we added the leds and wiring at one end, and blocked off the ends of the channel with hot glue and popsicle sticks to keep the resin from pouring out the ends as it cured. Finally, we poured the resin (mostly into the channel). Turns out polyester casting resin smells awful. We had to move theses new aluminum and resin light bars out of the garage to outside under a car to cure because they were stinking up the whole house with very toxic fumes.
Side note: even if your resin says it’s safe to use with good ventilation, don’t believe it if you look at the MSDS and see that it has an inhalation toxicity of 4. Seriously how do they think that’s even remotely safe?…
To solve the problems of the common positive always being on and the switches not lighting up, we figured out a relatively simple relay setup. There’s one relay for each color that connects the ground for that color when the corresponding switch in the cabin is thrown, and one relay for the common positive that turns on whenever any of the other relays are activated.
Finally we put everything together, soldered a ton of stuff, epoxied all the electrical joints to make them waterproof, and stuffed it all into/under the jeep.  We flipped a switch. Aaaaaaaaaaaaand…
Nothing happened.
In a mad rush to finish everything in time to get to a concert, I have mixed up 2 wires under the hood, and the strips were getting no power. However, after we got back from the concert it didn’t take long to figure out what was the problem, and about half an hour later we got everything working!
All the colors work, the switches light up, the magnets hold the strips to the frame really well, and I’d be willing to bet that this version is waterproof to the point of submersibility.
I have a bunch of pictures from the process and of the final product, but wordpress is making it really hard to fit them into the format, so there will be in an imgur album soon, I’ll edit in the link when it exists.
Thanks for reading, I hope you found the project interesting!