Motorized Bobbycar
Still a work in progress
I motorized a soapbox-style toy car with an electric drive, equipping it with two 4.3 kW brushless DC motors. To accommodate the significantly increased top speed, I replaced the original chassis, enhancing both stability and durability.
Steering
I upgraded the original solid plastic "tires" with air-filled tires designed for electric longboards, mounted on alloy rims.
The steering knuckles were machined from stainless steel, and the individual components welded together to ensure maximum stability.
The chassis mounting points are rigid, made from machined aluminum. I incorporated a 5° caster angle and an 8° kingpin inclination, with a dynamically adjustable toe angle
to improve handling.
I machined aluminum motor mounting brackets, and the rear wheels are driven using a belt drive. Belt tension can be adjusted via an eccentric cam. The rear axle is made of stainless steel.
The plywood sheet currently in use is for testing purposes and will eventually be replaced with a more durable aluminum plate.
The steering column is mounted using flange bearings and can be adjusted along the vehicle's axis to adjust for the plastic bod.
Battery
I custom-built a Li-Ion battery pack for this project using high-current 18650 cells. The battery pack is capable of delivering surge currents exceeding 130A at 11s.
A BMS (Battery Management System) ensures proper charge balancing and battery health. The cells were spot-welded, and the enclosure was 3D-printed for a precise fit.
The battery is centrally mounted to maintain weight distribution, and the speed controller is attached to the motor mounts. This setup keeps the center of gravity centered.
Fitting the battery into the chassis was a challenge and a key reason for designing a custom pack.
Controls
I designed custom controls for the vehicle. Two separate steering wheel levers manage braking and throttle. A custom control board interfaces with all controls, the LCD display, and the motor controller via CAN bus communication.
A graphical LCD panel displays odometry data. I implemented the UI using the LVGL library. The lever mechanism was machined from aluminum, the levers were made from fiber glass.
Chassis
I modified the chassis by removing its bottom section using an angle grinder. To reinforce the structure, I stabilized it using high-density rigid foam.
