Sinclair C5 24V Conversion with C5duino/Touchscreen

This project is no longer supported. The content below is provided for information only.
The Uni-8 Controller

Whilst 24V conversions have been around since shortly after the C5 was launched, none have featured a touchscreen display courtesy of the C5duino V2.0 developed exclusively for

As with many 24V conversions we will be using a uni-8 motor controller to provide means to power the C5 motor using something called PWM (Pulse Width Modulation) which allows you to precisely control the motor speed with an analog input.

As the C5duino does not directly control the uni-8 you can use any other suitable motor controller you like.

What Screen to Use?

The finished screen mounted on the C5

The C5duino is controlled with serial commands and anyone with some basic knowledge of programming and building hardware, whether that be Arduino, PIC or Arm, can create a screen with minimal effort and without having to get involved in the actual C5 hardware and dealing with tasks such as monitoring motor temperature, current, voltage, switches, lights etc.

For this 24V C5 I chose the touchscreen as detailed on the C5duino LCD Touchscreen page. This screen allows you to operate the C5 front/back lights from the touchscreen. There is also a button for hazard lights, and an extra button to control some other external lights.

Software Download

Here is the software for this project. You will need to download and install the Arduino program from and then upload this to your Arduino Mega and Nano boards. Instructions for uploading programs with an Arduino are provided on the offical website.

C5duino V2.0 Firmware
C5 LCD Touchscreen V2.0 Firmware
Arduino Libraries (LCD etc)


Some images showing the C5 with all the new components in place:

Latest from

Lotus C5 prototype by John Dunne It's a common misconception that Lotus only involvement in the C5 develop was the Y frame chassis, however as detailed in the Lotus World Magazine March 1985 & also in both of Barrie Will books who was the Managing Director of Sinclair Vehicle, Lotus developed, designed & build the C5 prototypes.
Lotus C5 prototype by John Dunne
posted on: 24/05/2020
Simplified Relay Controls This article by John Wilson shows how to re-wire a C5 with the original 12V motor.
Simplified Relay Controls
posted on: 27/04/2016
Control Clerk Training Notes Here are some rare C5 training notes from Hoover desgned for call centre staff and engineers.
Control Clerk Training Notes
posted on: 22/03/2016
Offroad Prototypes by Brian McCool For years there had been rumors about the Off Road C5's. Has anybody seen one?
Offroad Prototypes by Brian McCool
posted on: 10/03/2016