Summer on Michigan’s Great Lakes beaches brings clear water and soft sand, but it also brings a pile of coolers, chairs, towels, and everything else a family needs for a full day. Dragging that load from the parking area to a good spot gets old fast, especially when the temperature climbs. John Boss decided the usual wagon was still too much work. He built a remote-controlled cart that rolls the gear for him.
The starting point was an old cargo rack from one of his e-bikes that got left behind. That metal frame had loads of strength and some pre-existing mounting points, so he simply transformed it into a mobile platform. Next, he cut a sheet of 3/4″ plywood to size and fastened it underneath to give the structure a stable foundation to build on. Then ordered fat tires online that float exceptionally well over the soft sand, making them the ideal alternative to hard small wagon wheels. Each rear wheel has its own small axle, which is supported by pillow block bearings. Those bearings are then bolted to some simple 2×6 lumber standoffs, which provide adequate space for the tires and prevent the entire assembly from scraping down the bottom.
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The power comes from two 350-watt geared motors, one for each rear tire. These use chains and sprockets to transmit motion, allowing one wheel to turn independently of the others. That configuration allows the cart to steer by spinning one side around quicker or in the opposite direction, similar to a tracked vehicle, without the requirement for a sophisticated front axle. He initially utilized 3D-printed plastic drive flanges, but they flexed too much under strain, so he bought some stronger aluminum ones that would be more durable and not corrode from salt or lake water.
Down the center of the platform, two sealed 12-volt lead acid batteries are linked together to provide 24 volts. Lithium packs are expensive, so he used good old lead acid for the first prototype, which worked great. There’s a fuse on the positive side, followed by an automotive relay that is activated by a large aluminum pushbutton (he sourced it from his son’s ski bike) to turn the motor on and off. The electronics are all housed in plastic enclosures to keep the sand out, and a step down converter is used to reduce the 24 volts to a more manageable 5 volts for the system’s brain.
An ESP32 microcontroller lies at the heart of all the wiring, as it communicates with the motor controllers and listens for commands via Wi-Fi. The control panel on a phone allows you to use one hand to control the entire device using a virtual joystick. There are dual high intensity spotlights on the front to light the path for evening runs, as well as time of flight sensors that blast out a beam of light and signal the cart to stop if something gets too close. This safety precaution prevents the heavy cargo from running over children, dogs, or beach chairs.
Building the cart turned out to be a process of overcoming a host of minor issues one after the other, such as a few wiring problems that took a week to resolve. To get the wheels to fit properly, small printed shims were required, and chain tension was achieved through precise placement rather than sophisticated adjustable mounts. The first outside test resulted in a curious dog sniffing the moving tires, but further runs on the beach demonstrated it could carry a heavy cooler and several extra bags without digging in, though getting the tank-style turns to look smooth did require some work.
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