How To Connect An Electric Bike Controller

Despite flaunting an impressive motor and a high-capacity battery pack, you won’t comfortable E-bike experience unless you set up your controller. Although most off-the-shelf eBikes provide original controllers that are easy to repair and replace, converting a regular bike into an electric bike using an E-bike conversion kit can be somewhat difficult.

Nonetheless, setting up a DIY electric bike controller is really simple. After connecting all the other components (such as the battery pack, motor, sensors, etc.), you need to route the wires closer to the controller and connect them according to the connector design and color of the cables.

If you have any trouble understanding the fundamental cable connections and want to know more about how the controller works, bear with me as I’ll cover these and other topics such as:

• Understanding the different types of cables in an eBike controller
• Connecting an eBike controller
• Testing an eBike controller
• Basics of programming an E-bike controller
• Common Functions of an eBike controller

With that said, let’s begin.

Understanding the Different Types of Cables in most Electric Bike Controllers

The thing about E-bikes is that the more expensive and complete the package is, the easier it is to repair and replace. Setting up a controller on a complete E-bike or a fully featured DIY kit is much easier because the connectors and cables on these controllers are designed specifically for that kit or bicycle.

With fully-featured kits or eBikes, cable management is a breeze. On top of that, you don’t have to look around for compatible third-party peripherals (such as ignition switches, displays, etc.), or worry about programming the controllers.

In most electric bikes and conversion kits, you don’t have to understand all the wires coming out of the controller as long as you know about the fundamentals necessary to keep the E-bike running.

These “fundamental” cables are common among every electric bike controller, and these include:

• Battery Cables
• Three-phase motor wires
• Hall sensor wires
• Throttle/Pedal Assist cables
• Brake Cables

Let’s discuss their purpose.

Battery Cable

The battery cables are always easy to recognize because these two wires are located closer to each other. Most electric bike controllers have red and black-colored cable sheaths (indicating red for the positive voltage terminal and black for the negative).

These cables transfer from the battery pack to the electric bike controller, which manages the motors, and other loads in the electric bike.

Since these are power cables, they tend to be thicker depending on the power consumption of the electric bike controller; hence, it’s easy to identify them.

So, to recap: if you have relatively thick red and black wires sharing the same connector or situated closer to each other, those are the battery power cables.

Motor Power Supply Wires

After the battery cables, the second-most distinct set of power cables is the ones that feed power into the hub motor (or more specifically: the Brushless DC motor or BLDC). These cables are also easy to spot because have the same thickness with each having either blue, yellow, or green cable sheaths. (Representing the different phases or coils they connect to.)

In almost every DIY electric bike controller, these cables come in separate connectors. They are responsible for delivering current output in a sine wave or square wave (modified sine wave) pattern which makes the motor rotate smoothly. This AC-like pattern is created by the controller after taking in DC power from the E-bike’s battery pack.

Learning Cables

The learning wire or “self-learning wires” are more common among separate third-party sine wave controllers that do not include the hub motor and other accessories. These cables have the same colored sheath and come bundled together.

However, these “learning” wires have a female and male connector and are supposed to join together. (Creating a shunt/short circuit.)

The purpose of these wires: compensate for reverse motor configurations and throttle setups, making sure the phases and hall effect sensors operate in the correct sine/square wave sequence.

Reverse motor configuration happens when the phases of the motor do not match up with the phases of the controller (despite having the same colored wires). As a result, the motor rotates backward (anticlockwise). To remedy this, you can switch out the phases or join the male and female learning wires together. It will “undo” the initial motor phase sequence and rotate the motor in the opposite direction.

Also, depending on the electric bike controller, joining/shorting the learning wires could reverse the operating principle of the throttle (the motor will only slow down or stop when you twist or push the throttle.)

Therefore, it’s recommended to switch out the phase connectors (and try to get clockwise rotation that way) instead of counting on these “learning” wires.

(To see this in action, skip to 7.50 on this video.)

Hall Sensor Wires

The hall sensors are used to identify the position of the rotor with respect to the stator, and the signals from these sensors are necessary to keep the motor rotating smoothly. The input from the hall sensors determines the output of the phase wires.

Although sensorless BLDC motors exist, without the hall sensors, the E-bike wouldn’t be able to maintain torque or speed properly.

The hall sensor wires are very easy to spot since it comes with five or six small wires sharing the same connector. In some motors, the hall sensor might require six wires, but if you can make these five wires fit inside, it will work seamlessly.

Throttle Wires

Next up, we’ve got the throttle wires. These usually come with three small wires (red, black, and white) connected and sharing a single plug.

The red wire manages positive voltage, the black: negative, and the white wire transfers the acceleration/speed signal from the twist or thumb throttle.

Throttle connectors come in two different interface designs: the SM plug or a waterproof plug that looks like an XLR connector. Here’s where purchasing third-party controllers and throttles can go wrong, so make sure you check the connector type of the throttle before purchasing.

For beginners, I recommend this throttle as you can pick either option. However, if you are somewhat skilled in DIY wiring and want waterproof connections, you can install these adapters between your controller and throttle.

Brake Cables

The brake line cables are also easy to distinguish since the wiring branches off into two connectors after coming out of the same thick wire. Both these branches have the same type of connector and include two wires on each connector (hence, four in total).

The brake cables act as a switch, so whenever you pull on the brakes, the switch closes (gets connected in a short circuit), sending a signal to the controller. (Wherein it stops the motor from acceleration.) It is an important safety feature, and you need to make sure you set it up.

With complete conversion kits, you will be provided with brake levers with the sensor and compatible connectors built-in. However, if purchasing products separately, there’s the option between separate brake levers or a pair of hall sensors with appropriately sized magnets. (Both options include the same amount of wiring, but with the latter, you won’t need to replace your existing brake cable/levers.)

For examples of how to install the hall sensor magnets, check out this video.

Pedal Assist Cables

Certainelectric bike controllers, especially ones that come with a complete mid-drive conversion kit, will include dedicated connectors for the speed sensors. The appearance of these connectors will vary depending on the kit, so check the datasheet accordingly.

The wiring for this pedal assist system often includes a cadence sensor you can fit between the cranks and the pedals or a conventional speed sensor that uses a spoke magnet.

Unfortunately, setting up pedal assist for separate controllers can be difficult, and in most third-party hub motor controllers, this is not even an option.

Other Cables

Apart from the wires mentioned above (which maintain the critical functions of an E-bike), there are optional connectors such as:

• Ignition Switch
• Motor Speed Function
• Cruise Function
• Headlights, Brake Lights
• Horn/Phone Charger
• Display Screen

So before purchasing a separate controller, make sure to check these optional connectors and purchase the required components, if necessary.

How To Connect An Electric Bike Controller

Initializing the Controller

If you convert your E-bike using a dedicated kit or separate components, you need to connect the different components and test them before installing them on your bicycle.

Since it is difficult to test the hub motor, you can install it beforehand and house the bicycle on a repair stand. That way, you can test all the motor functions with all the other components that are yet to be installed.

Connect the battery, throttle, bicycle light, and any other peripherals you want to test and switch on the battery. (Make sure you don’t reverse the positive and negative terminals on the battery).

Here are a few things you need to check:

• Check the throttle, and see if the signal works in the proper order.
• Check the motor rotation; it is supposed to be clockwise.
• Try the brakes. See if the bike’s motor cuts out when you pull on the brake levers (or pull the magnet away from the hall sensors)
• Check the display, make sure it lights up, and show the correct speed (only works if you install the speed sensor)

Before you figure out where to set up your electric bike controller, it’s highly recommended you install all the other components (such as the rear wheel hub motors, battery, speed sensors, etc.). Because then, it’s easier to determine where all the wires can meet and get connected to the controller.

Figuring Out Where to Fix the Electric Bike Controller

In most cases, you will have to install the battery pack on the down tube (by replacing the water bottle cage), and the battery will have a very short wire. Therefore, you are most often limited to the main triangle area (downtube, top tube, seat tube) in which you can mount the controller.

So, find a spot on the main triangle where the battery line and all the other wires can meet (while also having some slack). If you are purchasing all the components separately, you might need to get additional cable extenders, especially for the motor wires coming from the hub motors to the controller.

(So basically, buying everything separately can be a nightmare and potentially cost twice as much, especially if you don’t have additional connectors, cables, and tools.)

Installing the Electric Bike Controller

The next part is getting the electric bike controller mounted onto your bicycle frame. Unless your kit provides one, you will have to purchase a controller box/case separately.

You can mount the controller directly using screws or zip ties (especially when you take it out for a test ride). Nonetheless, for added protection from the elements and insulating it from the metal frame, I recommend using a dedicated case or box.

There are tons of options, but make sure the dimensions match that of your controller.

Testing an Electric Bike Controller

If several wires on your new electric bike controller are not working, you can test the connections using a multimeter or a dedicated E-bike tester. However, please note that if you remove the enclosure, it might void the warranty.

Using a Multimeter

To diagnose a short circuit or fault within the controller, you need a simple multimeter with resistance or continuity settings.

First, switch to either setting and test for continuity between the positive and negative battery connectors. (If you can’t reach the metal connections, you might have to remove the cover and carry this out directly on the printed circuit board.)

If the resistor reads less than 8kΩ or the multimeter beeps, you’ve got a short between these two battery leads. After that, keep one lead connecting to the positive battery terminal and test for continuity on all the other wire connections. Finally, repeat the process with the negative terminal. (just to be sure.)

It is only a simple method of checking for short circuits, and if you still find any issues, it might be best to get it looked at by a professional.

Also, you can use an E-bike tester to diagnose the issue.

Picking Out an Electric Bike Controller

Although most controllers are the same, here are some things you should know about when picking a separate controller.

Voltage: Voltage is crucial. Make sure you pick out a controller that supports the voltage of your battery and motor. A 24V system will not work with your 48V eBike and vice versa. Luckily, most third-party controllers are designed to work within a range of 24V-48V.

Power: If you have a particularly high-power motor (such as a 1000W or 1500W), you might need a high-power electric bike controller because of the higher current flow.

Display: Also, don’t forget to pick out a compatible display that goes with the controller. Some kits will sell you the controller and the display screen, so don’t forget to check those out.

Conclusion

Connecting an electric bike controller is quite simple as long as you understand the different connections and where they go. The hard part is mounting it on your bicycle and ensuring it’s compatible with all the other third-party components.

Nonetheless, if you make it through this guide, you will understand what the electric bike controller does and how you can set one up for your electric bicycle.