E-Bike Repair Knowledge Base:
Fault Diagnosis, Fixes & Wiring Diagrams

FAQ

Quick answers to common e-bike questions and repairs

• When the electric bicycle’s power switch is turned on, why doesn’t the “Power” indicator light on the controller panel come on?

  When the electric bicycle is turned on, the “Power” indicator light on the controller panel may fail to illuminate due to the following common causes: poor contact between the cable plug and the battery socket; a blown fuse beneath the battery socket; or a broken internal connection between batteries in the battery pack. Use a multimeter to test these components, then troubleshoot the issue step by step based on the actual cause.Pay particular attention to whether the plug is securely connected and whether the 15A fuse is damaged.

• What is the basic principle of an electric bicycle’s speed control twist grip?

  The speed control throttle on an electric bicycle uses a Hall effect sensor, which can be classified as either a switching Hall sensor or a linear Hall sensor.The three leads of the Hall sensor are arranged according to the standard: green (signal), red (power), and yellow (ground). They are designed to be used with different controllers and bike models, and are commonly available in long (1200 mm) and short (450 mm) versions.

  The operating principle of Hall effect sensors is as follows: when a magnetic field is present at the sensing surface of a switching-type Hall effect sensor, the sensor outputs a low-level signal; in the absence of a magnetic field, the opposite occurs. Speed control is achieved based on the presence or absence of the output signal, and the supply voltage ranges from 4.5 to 24 V;In contrast, linear Hall sensors regulate speed based on changes in the strength of the magnetic field detected by the sensor’s sensitive surface. When the supply voltage is 5 V, the output signal voltage varies linearly and continuously between 1.0 and 4.2 V. The appearance of the speed control twist grip is shown in Figure 1.

  

  Figure 1: Appearance of the speed control twist grip

• How can you determine the charge level of an electric bicycle battery?

  1. Every electric bicycle is equipped with a battery charge indicator light; you can determine the battery’s charge level based on the light’s status.Note: The shallower the depth of discharge each time the battery is used, the longer its service life will be. Therefore, regardless of the capacity of the battery pack, you should develop the habit of charging it as soon as you finish using it.

  2. Use a voltmeter to check the voltage of each cell in the battery pack. If the voltage is less than 1.27V, the battery should be charged; otherwise, the plates will oxidize and become damaged.

• How can you quickly diagnose a battery fault?

  When an electric bicycle battery malfunctions, first inspect the battery’s exterior. The casing should be free of cracks and leaks, the surface should be clean, the terminals should show no corrosion, the positive terminal insulation should be intact, and the battery should not exhibit self-discharge.Next, check the battery terminals; they should be secure and the ground connection should be reliable. Then turn on the headlight to test it. If the light is bright and white, the battery is functioning normally; if the light is dim and reddish, the battery is low on power.

  After completing the above checks, turn on the power to start the motor. If the rotational speed is normal and the light dims slightly but remains sufficiently bright, the battery is in good condition. If the motor starts weakly and the light is very dim, the battery is deeply discharged and must be recharged immediately. If the light turns dark red when the motor is turned on, the battery is either completely discharged or the plates are severely sulfated.

• What are the functions and operating principles of a smart display on an electric bicycle?

  Smart display panels for electric bicycles require a corresponding controller to turn the LEDs on and off. They display a wide range of information, including whether the riding mode is “Power Assist,” “Electric,” or “Cruise Control,” but cannot display high, medium, or low battery voltage levels or indicate whether the battery is under-voltage.

  When a smart instrument panel malfunctions, the issue can be diagnosed based on the LED display: If the indicator light flashes three times, check whether the indicator light is functioning normally; turn the throttle, the flashing frequency of the “Undervoltage” indicator light should correspond to the angle of throttle rotation; the power indicator lights indicate the power status of the three Hall effect sensors and the position of the motor’s permanent magnets;Press the mode switch button; the “Power Assist” indicator light should illuminate. Turn the left or right brake levers; the “Electric” indicator light should illuminate. Pedal the wheel; if the indicator light flashes five times, it indicates that the power assist sensor is functioning normally. If the instrument panel does not display according to the above patterns, it indicates a malfunction and needs to be replaced.

• What are the advantages of proportional-control electric bicycles?

  Proportional-power electric bicycles feature an auxiliary power source that supplements pedal power, ensuring a consistent and comfortable riding experience for the rider regardless of whether climbing hills, riding into headwinds, or traveling on flat terrain: the auxiliary power source is controlled by an internal circuit, and operation is similar to that of a standard bicycle; furthermore, pedal power can be combined with motor power, allowing for the use of a smaller battery and thereby reducing the vehicle’s overall weight.