Wiring a scooter controller: phases, Hall sensors, throttle, and brake
A scooter controller connects to four different systems: the battery, which powers it; the motor, which it drives; the controls (throttle, brake, power switch), which tell it what to do; and the display, with which it communicates. Each group of wires has its role, its usual colors, and its potential pitfalls. This guide reviews them, to help you understand an existing wiring harness or prepare for a replacement. It does not replace the wiring diagram provided by the manufacturer of your controller: the colors and order of the wires may vary from one brand to another.
The essentials
- Always work with the battery disconnected, and double-check the polarity before reconnecting it each time.
- The three main phase wires connect to the motor; their order determines the direction of rotation and must correspond to the sensor configuration.
- The Hall sensors of the motor are connected using five thin wires: power, ground, and three signal wires.
- The throttle and brake often use the same 5V power supply as the sensors: a short circuit on this wire can shut everything down.
- The colors are not standardized; instead, refer to the wiring diagrams for the controller and motor, not the colors themselves.
Safety first, before even connecting the first wire
A scooter battery can deliver a massive amount of current in the event of a short circuit, enough to melt a wire or damage a tool. Before working on the wiring:
- Disconnect the battery, or isolate it using a circuit breaker
- Isolate each loose power wire with heat-shrink tubing or a cap
- Always work with insulated tools, and never work alone on the battery itself.
Power supply: battery and connection
Two thick wires come from the battery: the positive wire (often red) and the negative wire (often black). Their gauge must correspond to the battery's current rating: a wire that is too thin will overheat. Our guide on power cables and connectors explains how to size them correctly.
Many controllers also have a thin "contact" wire (sometimes called a key, ignition, or enable wire): this wire activates the controller when the scooter is turned on. It is typically connected to the positive terminal of the battery via the switch or the display.
When the battery is connected, the controller's capacitors charge rapidly, which can create a spark. An anti-spark connector or a pre-charge circuit prevents damage to the contacts.
The phases: these are the three main wires of the motor
The motor is connected to the controller by three thick wires, the phases, which are typically yellow, green, and blue. These wires carry all the current that drives the wheel. They must be as thick as the battery wires, or even thicker, and their connectors must be tight and clean. On our MHS, MHT, XHS, and XHT motors, the phases connect using 8mm AMASS bullet connectors.
The order of the three phases matters
- With Hall sensors, the order of the phases must correspond to the order of the sensors. Incorrect pairing will cause the motor to vibrate, run poorly or in reverse, and overheat
- Whether operating in sensorless mode or in FOC mode after motor detection, reversing two phases simply reverses the direction of rotation.
Many controllers offer an auto-learning function that finds the correct pairing. Otherwise, the method involves trying different combinations while the wheel is raised and with low current, until you achieve a smooth, quiet rotation in the correct direction.
Hall sensors: five thin wires
The Hall sensors indicate the rotor's position to the controller. They are connected via a five-wire connector:
| Fil | Role | Common color (non-standardized) |
|---|---|---|
| Power supply | Power the three sensors (typically 5V) | Red |
| Mass | Common feedback | Black |
| Hall A, B, C | A signal is generated by a sensor, which changes state when a magnet passes by | Yellow, green, blue |
| Temperature sensor (if present) | Measures the winding temperature | Variable, often a sixth wire |
A faulty sensor or a poorly seated connector can cause the motor to stutter, hesitate, or only start when pushed. Our guide on Hall sensors, encoders, and resolvers explains how they work. Be careful not to reverse the power and ground connections, as this can damage the sensors.
The throttle
Most scooter throttles (thumb triggers or twist grips) also use Hall effect sensors. They have three wires: power, ground, and a signal wire where the voltage increases as the throttle is pressed. The controller reads this voltage and converts it into a torque or speed request.
On an adjustable controller, it's crucial to specify the actual resting and full-throttle voltages provided by your throttle, otherwise the range will be poorly utilized, or the motor will remain slightly engaged even when at rest.
The brake
Two types of braking signals exist:
- Brake contact: A simple switch located within the brake lever, which cuts off acceleration as soon as the brakes are applied, and, depending on the controller, activates the electric braking system. It can operate in "high-level" or "low-level" mode: the controller must be configured accordingly
- Progressive electric braking: A second trigger, wired like an accelerator, which controls the intensity of the electric braking. A trigger, such as our 370X, can function as either an accelerator or an electric brake depending on its wiring.
A poorly adjusted or wet brake contact can cause unwanted braking: the scooter jerks, especially when going over bumps.
The display and communication
The display communicates with the controller via a serial connection or a CAN bus, depending on the model. It sends information such as the driving mode, headlight status, and sometimes the anti-theft system activation, and receives data like speed, battery level, and error codes. The communication protocol for this connection varies depending on the manufacturer: a display from one brand typically cannot communicate with the controller of another. This is often a critical issue when attempting to replace the controller.
The most costly mistakes
- Reversing the positive and negative terminals of the battery, even for a short period, can cause damage
- Allow a phase wire to rub against the frame or the axle housing
- Short-circuit the 5V supply to the sensors or the throttle
- Connect two controllers by connecting their control wires without verifying the wiring diagram
- Running the signal wires alongside the power wires for the entire length can interfere with the sensors.
Workshop tip
Before disconnecting anything, photograph each connector and label each wire. An hour of wiring can be lost in ten seconds with a reversed connector. And if you're changing controllers, opt for a well-made, clean, and labeled wiring harness, rather than a series of connections: this is the subject of our guide creating a plug-and-play motor controller setup.
Get help
Rage Mechanics does not currently sell controllers, but the workshop can cable and configure complete setups. Depending on the situation: the complete assembly package for a full installation, the motor-to-controller plug-and-play conversion to reuse the motor connectors, or, for the Nami Burn-E, our Nami plug-and-play wiring harness, a complete wiring harness to install VESC controllers and the SmartDisplay without reusing the original wiring.
Frequently Asked Questions
What happens if I reverse two phase wires?
In sensorless mode, or in FOC mode after motor detection, the motor simply rotates in the opposite direction. With Hall sensors, the combination may no longer be correct: the motor vibrates, runs poorly, and overheats. In this case, it is necessary to re-calibrate or find the correct combination.
Can I rely on the colors of the wires?
No. The standard colors (red, black, yellow, green, blue) are not a fixed standard, and two different manufacturers may use them differently. Only the wiring diagrams for the controller and the motor are definitive.
Why is my motor turning slightly even when I'm not touching the accelerator?
The throttle's resting voltage is likely above the threshold set in the controller. You need to adjust this threshold to the actual voltage measured when the throttle is at rest, with a small margin for error.
My motor has six thin wires instead of five; is this normal?
Yes, often: the sixth wire is generally used for a temperature sensor in the motor. The controller can use this information to reduce power before overheating, provided it has the corresponding input.