Electric scooter display: what it does, how it communicates, and its limitations
The display on an electric scooter might seem like just a screen that shows speed and battery level. In reality, it's often much more: on many models, it's responsible for powering on the scooter, reading the throttle input, storing settings, and transmitting them to the controller. Understanding its role helps in diagnosing problems, knowing what replacing the display entails, and understanding why you can't simply replace a display with any other model.
The essentials
- The display constantly communicates with the controller via a data link; it doesn't measure the speed itself, but receives it.
- On many scooters, it also houses the power switch, the throttle, and the settings menus.
- Each manufacturer uses its own communication protocol. Therefore, you cannot simply swap out a display for another without also, often, changing the controller.
- It doesn't generate power; it requests it. The controller decides how much power to deliver, and the battery provides it.
- On public roads, an electric scooter is limited to a maximum speed of 25 km/h, regardless of the displayed speed.
What a display does
A scooter display combines several functions, with the number of functions varying depending on the model:
- `Display: speed, battery level, driving mode, distance traveled, sometimes temperatures and error codes;`
- Controls: Power on/off, mode selection, lighting, horn, and sometimes cruise control;
- `Settings: menus for parameter adjustments (speed limit, starting torque, electric braking, units, wheel diameter);`
- Transmission: On many mass-market scooters, the throttle and sometimes the brake contacts are connected to the display, which sends the signal to the controller via the data link.
This last point often surprises people: on these machines, a malfunctioning display can prevent you from riding, even if the motor, battery, and controller are in perfect working order.
How it communicates with the controller
The display and the controller continuously exchange messages, several times per second. The controller sends data such as the speed (calculated from the motor's rotation), battery voltage, and any error codes; the display sends information like the throttle position, the selected mode, and the settings.
Two main types of connections are prevalent:
- Serial communication (UART): Two data wires, one in each direction, connecting a display to a controller. This is a simple and very common method used in many consumer-grade electric scooters
- The CAN bus: Two wires shared by multiple devices (controllers, BMS, display, GPS module, etc.), with priority management and excellent resistance to interference. It is found on more sophisticated machines. Our guide on the CAN bus explains it in detail.
In both cases, the content of the messages, i.e., their protocol, is defined by each manufacturer. A display from one brand is not compatible with a controller from another, even if the connectors look similar. This is why changing the controller often requires changing the display as well, and vice versa.
What the display cannot do
A display simply shows information; it doesn't actually produce power. Changing a power setting in its menus will only increase the power output if the controller, motor, and battery have the capacity to deliver it. Beyond that, the controller will be limited by its own internal limits, or the battery will shut down to protect itself.
It also doesn't measure much on its own: it receives speed, voltage, and temperature data from the controller. An inaccurate speed reading often stems from a poorly calibrated wheel diameter setting; a battery level that jumps erratically during acceleration simply reflects the voltage drop of the battery under load.
Finally, speed settings do not change the law: on public roads, an electric scooter is limited to 25 km/h. More permissive settings only apply on private property or on a closed circuit. See our guide unlocked scooter: what the law says.
Problems that originate from the display, or that appear to be related to the display
- Screen not turning on: This could be due to a blown fuse, a pinched cable near the steering column, a corroded connector, or a battery where the BMS (Battery Management System) has cut off power. The display itself may not be the problem.
- Communication error code: This indicates a disruption in the connection between the display and the controller, which is often caused by a damaged wire in the steering column or a poorly connected connector.
- `Inconsistent or restarting display: Interference, voltage drop during hard acceleration, water ingress in the display.`
- Buttons or throttle with no effect: This can be caused by a worn sensor or moisture on the display that controls the throttle.
Our guide on what to do when your scooter display turns off or shows incorrect information provides the steps for troubleshooting.
Workshop tip
Before ordering a new display, inspect the cable that runs down into the steering column. It twists with every fold and rotation of the handlebars, and it's the part that most often fails. A display that flickers or disappears when you move the handlebars almost always indicates a problem with the cable, not the display itself.
More comprehensive displays
On modified and racing machines, the display becomes a true dashboard, providing information such as motor and controller temperatures, instantaneous power, lap times, and data logging. It is often connected to a shared bus with other modules.
Our SmartDisplay is integrated into our custom builds; for example, it receives our EB6 GPS module, which is connected to the CAN bus, and can be protected by an aluminum enclosure that replaces the standard enclosure. Furthermore, the RageLink range offers three displays (View, Mini, and Apex) that connect directly to the controller, with a system that is configured via a smartphone; they are currently on backorder.
Frequently Asked Questions
Is it possible to install a display from a different brand on an electric scooter?
It's rare to be able to change just the controller. The communication protocol is specific to each manufacturer: even with the correct wiring, the two devices wouldn't understand each other. A display is purchased with a controller that speaks its language.
My electric scooter is displaying an inaccurate speed reading. Why is this happening?
The speed is calculated based on the motor's rotation and the wheel diameter setting. If you have changed the tire or motor, or if the diameter setting is incorrect, the displayed speed will also be inaccurate. A GPS can be used to verify the speed.
Why does the battery level decrease when I accelerate?
Because most displays estimate the battery level based on voltage, and the voltage of a battery drops during periods of high current draw. It recovers when the battery is at rest. Only systems that read the Battery Management System (BMS) or measure the energy consumed provide a stable level reading.
Can changing settings on the display damage the scooter?
Yes, if you demand more than the motor, controller, or battery can handle, you will experience issues such as overheating, BMS shutdowns, and accelerated wear. Change one setting at a time and observe the behavior, especially the temperature.