Electric Bobby Car Hoverboard Upgrade

This project puts four 350W hoverboard motors in a Big Bobby Car toy vehicle, to give it independent four wheel drive and a top speed of 29km/h with turbo activated. All controlled by two potentiometer triggers on the steering wheel.

• Electric Hoverboard Monorover R2 Teardown

Specifications

• Project start: January 2019
• Main controller: STM32F103 72MHz ARM Cortex-M3 core
  • Flasher: ST-Link V2 Programming Unit clone
• Motors: 4x direct drive 3-phase brushless DC electric wheel hub motors with hall effect sensors, 350W ea
• Tire type: non-pneumatic rubber tire, road pattern
• Tire size: 7-inch / 170 mm
• Battery: Lithium-ion rechargeable 18650-cells, 10S2P 36V 4400mAh 158.4Wh pack with XT60 connector
  • Upgrade: Controller can handle 13S (48V), 12S battery upgrade easiest
• Charger: Lithium-ion charger 42V 2A 3-pin connector with built-in fan
  • Upgrade: External charger for anything else
• Internal connectors PCB: JST Sales America B4B-XH-A 2.5mm pitch
• Vehicle base type: BIG New Bobby Car Red
• Dimensions assembled: L57 x W30 x H39 cm
• Original load-bearing: 50 kg max.

Overview

A rough overview of the components in the system.

Schematics

• File:Hoverboard schematic full reverse.pdf - Full reverse engineered schematic of the classic hoverboard circuit board
• File:Hoverboard schematic simple reverse.pdf - Simple schematic the circuit board

Pin-out

Pin-out of the hoverboard connections, by NiklasFauth:

STM32F103 MCU pin-out:

Throttle filter and connection board

This is a PCB I designed to break out the ADC/UART/PPM/I2C signals to make it easier to finish the build. It also adds filtering to the analog signals and pull-ups to the I2C lanes. All configurable via solder-jumpers. Inspired by the Jan Henrik break-out boards.

• File:Bobbycar hoverboard throttle breakout schematic.pdf - Schematic of the throttle filter and connection breakout board

Inspiration

• Larsm Allrad e-Bobby Car - great write up and custom firmware fork
• Niklas Fauth Hoverboard firmware hack - original firmware
• Fisch's detailed build guide - great documentation of the assembly
• Jan Henrik breakout boards - for easy connection to serial and Nunchuck