yeah, i went the past 2 years. sadly driving a project down wasn’t in the cards. Both times i brought a body mounted project though. First year it was a 3d printed cat treat dispenser that would track the distance my cat runs on a cat wheel, then gives him a single treat after he runs a certain amount. I had a mini version mounted on my chest. This past year, i brought some arm mounted EDF’s that I plan on using to propel myself on skiis in the snow. I plan on making videos about both eventually, but im trying to space out larger projects like those (and the cooler kart) with smaller ones :)

yeah, the emergency kill switch had the full power going through it. I did something similar with relays on the back with the initial esp32 control, where if the relays were powered but no signal was sent to the relays, it would close the brake pins on the cheaper ESC’s as another safety feature.

it was kinda cool, a little kid (like, elementary school aged) came up and was asking about the project, with his dad right behind him. the kids questions were all pretty much around how he could potentially make something similar. I answered them in an age understandable way, but also walked through all the different potential failures and how it related to saftey, and how I added things like the relays, battery fuse, and cut off switch to mitigate the risks. basically saying “yeah, making something like this is dangerous, but you shouldn’t let that get in the way of making your ideas a reality - its just important to walk through those risks and mitigate them as best as you can, and think if you can reach an acceptable risk before you spend money and time”. The dad didn’t say anything, but i could tell he was beaming since the kid was realizing all the safety stuff, and realizing that thinking through that stuff is very important. about 1/2 way through, the kid was just asking more safety related questions haha

well, I wanted to to be a goofy and unique project, so having the wheels be in the “normal” location would be a less interesting to me. Also, the trike had a “male” axle for a wheel to mount to, and the hoverboard wheels also had a “male” stub coming out of the motor hub, so mounting them together would have required something to offset and join the parts together. Since I wanted to do 2 wheels on each side, a triangle just kind of made sense. In retrospect, they should have been a bit shorter so the top of the cooler was level. I chose to not use cad, since i have been relying on it a lot for other projects, and sometimes its fun to just make something and kind of make it up as you go along, but if i had designed it in the computer first, then i would have realized that the rear wheel height was too high. :)

yeah, the VESC firmware has traction control settings, so each speed controller is talking to the others and has a maximum allowed speed range between the wheels, which might help for sand? trying to accelerate on wet grass, there was a bit of slip, but you could hear the motors all micro adjusting their speed, and eventually you would get moving enough that they all went back to full power. sand might be a bit harder because the wheels + weight would want to dig into the sand.

but yeah, it was pretty nice - when i went to the general store to get ice, the people working there were unloading ice from a truck up on the street, and walking it down in plastic bins (probably a 2 or 3 minute walk from their van). They looked at the cooler kart with envy haha - so i could see some applications for it, but they are all fairly niche, and less transportation focused i suppose

oh, thats a good point on the heat issue with solder… i mean the BMS and fuse should save it, but i hadn’t thought of that. Do you have recomendations for how to attach the main bus wires coming off the battery in a non soldered way? cause with flat top 18650 based batteries, you have to spot weld nickel strips, and soldering the main wire to the strip before spot welding is the only thing i can think of. If you go with something like headway lifepo4, they are screw top, so you could fab a contact plate that the wire crimps into, then screws to the battery, but yeah - no idea how to do something like that with flat top batteries.