E-bike Wiring Guide: Types of Wires, Gauges & Connectors

Power Wires vs. Signal Wires

E-bike wiring is broadly split into heavy power wires (carrying battery current to the motor, lights, etc.) and thin signal wires (carrying throttle, brake, PAS, hall sensor signals, etc.). Power cables must handle high amperage without overheating, so they use low AWG numbers (thick cables) and sturdy insulation. 

Signal cables carry only small currents (milliamp to a few amps) and can be high AWG (thin). For example, a typical 48V 500W system (~10–12A continuous) will use 12 AWG battery cables (up to ~20A capacity), whereas the throttle and brake switch use thin 20–22 AWG wires. 

The wiring harness often color-codes these circuits: red/black for battery power, and green/yellow/blue (plus others) for motor/sensor signals.

Wire Gauge and Ampacity

The gauge (thickness) of an e-bike wire dictates its current-carrying capacity (ampacity). 

Smaller AWG numbers mean thicker wire. For instance, 12 AWG copper (~2.05 mm diameter) safely carries about 20–25 A continuous, while 10 AWG (~3.25 mm) handles ~30 A. 

The table below lists common wire sizes and their approximate ampacity in e-bike use:

For most mid-range e-bikes (e.g. 450–600W at 24V), 12 AWG copper is standard. Thicker 10 AWG or even 8 AWG may be used for high-power (2 kW+) motors or long cable runs to minimize voltage drop. 

Always choose a heavier gauge if you experience overheating or voltage sag. In practice, keep power wiring runs as short as practical and ensure connectors (soldered or crimped) match the wire’s ampacity.

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Copper vs. Aluminum Conductors

Most e-bike wires use copper conductors because copper has high conductivity and flexibility (especially tinned multi-strand copper). 

Aluminum or copper-clad aluminum (CCA) wires are lighter and cheaper but have roughly 60% the conductivity of copper, meaning they must be thicker to carry the same current. For example, 12 AWG aluminum is only about 15 A capable, versus ~20 A for copper. 

In short runs this may be acceptable, but for most e-bike applications pure copper (often tinned for corrosion resistance) is preferred. High-end kits may even use silver-plated copper for extra corrosion protection. 

Remember: a heavier gauge aluminum wire can equal a thinner copper wire’s performance, but copper is generally the standard for e-bike wiring.

Insulation and Durability

E-bike cables must be rugged and flexible. 

Silicone insulation is widely used because it remains pliable when bent and resists high temperatures (often rated to 150–200 °C). Many e-bike wires are silicone-jacketed, especially for motor and battery cables. 

PVC insulation is cheaper but stiffer and can crack with vibration. 

The wire’s insulation thickness also sets its voltage rating; most e-bike wires are rated ≥300 V which is ample for 36–48 V systems. 

For all-weather use, many kits employ waterproof cables and connectors. For example, Higo-style cables use overmolded rubber housing and gaskets to fully seal the connection, with ratings around 20 A and 60 V. 

Heat-shrink tubing and cable glands are often used at junctions to keep out moisture. Proper strain relief (like cable ties or boot covers) is also important on long runs to prevent chafing or fatigue. 

In summary, choose insulation that matches your riding conditions: silicone for flexibility, and sealed assemblies for wet environments.

Wire Color Codes

Standard color-coding helps identify e-bike wires. Red is almost always battery positive (+), black (or brown) is ground (–). The three motor phase wires are often yellow, green, and blue (or similar colors), matching the controller output. A typical brushless hub motor cable bundle has 8 or 9 wires:

• 3 phase wires: Yellow, Green, Blue (carry the main AC power to the motor).

• 5 hall-sensor wires: Red (5 V supply), Black (ground), and Blue, Green, Yellow (Hall A, B, C signals).

• Optional 9th wire: White for a speed/tachometer sensor (less common).

• Other harness colors: Throttle cables often have red (5V), black (GND), and green/yellow for the throttle signal. Brake cut-off switches use two small wires (commonly green and white) that short to ground. PAS sensors and displays have their own multi-wire cables (common colors are red, black, white/green). 

Always consult your controller’s wiring diagram, but these conventions are typical for most Chinese kits.

Connectors and Cable Types

E-bike wiring uses a variety of connectors and cable assemblies:

Battery Connectors

High-current plugs like XT60 connectors (60 A continuous with 12 AWG wire) or XT90 (90 A). These are soldered or crimped onto 10–12 AWG silicone cables. Anderson Powerpole or SB50 connectors (30–45 A) are also used, as well as larger SB350 for >60 A.

Motor Phase Connections

The three phase leads often end in 6 mm bullet connectors (three pairs) for plugging into the controller. These copper bullet plugs are typically crimped onto the 12–14 AWG wires and insulated by plastic housings.

Signal Connectors

JST-SM series connectors (0.1″ pitch) are ubiquitous for throttle, brake, PAS, and hall-sensor wiring. They come in 2–8 pin versions and handle up to ~2 A. For example, a 3-pin JST is used for many throttles/brake switches.

Waterproof Connectors

In many higher-end or European bikes, overmolded connectors (often referred to as Higo or IP65-rated plugs) are used for throttle, PAS, and light wires. These connectors have rubber seals and secure latches. Higo connectors are typically rated ~20 A and keep water out.

Proper crimping (with solder for extra safety) is recommended for all high-current connectors to minimize resistance and heat.

Application-Specific Wiring

E-bike cables vary by component:

Battery Pack

The main pack output wires are heavy gauge (usually 10–12 AWG), often silicone-jacketed. They connect to an XT60/XT90 or Anderson plug, and include a master switch or fuse. Inside the pack, cell balance leads are very thin (30+ AWG).

Motor Wiring

Hub motors have 8–9 wires. Three phase wires (12–14 AWG) handle motor current. Five hall sensor wires (typically 26–28 AWG, bundled in a single connector) carry +5 V, ground, and the three small hall signals to the controller. A ninth wire (if present) is for a speed sensor.

Controller Harness

The controller has a pigtail for the battery input (thick wires), three outputs for the phase (bullet connectors), and multiple smaller plugs:

• Throttle (3- or 5-pin) carrying 5 V/GND/signal (20–22 AWG) to control speed.

• PAS sensor (3 or 5-wire connector) for pedal cadence signals.

• Brake cut-off (2-wire) that opens the circuit when the lever is pulled.

• Display/LCD plug (often 5–9 wires, carrying power and data).

• Light outputs (2-wire each for head/tail lamp, typically 18–20 AWG).

Selecting the correct wire gauge and connector for each use-case is critical: battery and motor circuits need thick, low-resistance cable, while sensor and indicator wires can be much thinner.

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By understanding these wiring types and standards, you can build and maintain safe, efficient e-bike electrical systems.