Key Takeaways:

  • Controller type depends on the motor’s power level and voltage requirement
  • Some electric bike speed controller units allow features like variable pedal assist
  • Higher amps will require thicker cable and controller wiring

When trying to decide what controller to use in your new electric bike, there are several options to consider. First, make sure of the voltage and current requirements and that the controller can handle them. Running too many amps through a controller can cause it to overheat.

Speed Controller Types for Different Motors

It’s important to choose a motor controller that matches the power rating of the electric motor you’re using as well as the battery pack voltage. A 24-volt controller and 6 cell battery will operate a 36V motor, but the motor’s speed will be limited and it won’t reach its claimed output in watts. Running a controller rated for fewer volts than the battery and motor, however, risks overheating and burning out the connectors.

Choosing a Speed Controller for Your Motor

It’s also important to match the controller and motor type. A brushless motor requires a brushless motor controller. Some controllers require a motor with hall sensors, while some can be operated sensorless. Switched reluctance motors work best with a sophisticated sine wave controller. This type of brushless controller comes at an additional cost but provides smoother acceleration.

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Controllers for Brushed Motors

A 500W electric bike brushed motor controller is simpler than the typical brushless speed controller. A brushed DC motor’s speed depends on input voltage and can be controlled by a rheostat, so an electronic “controller” isn’t strictly necessary. Brushed motors also tend to be less efficient, so a brushed motor eBike won’t get as much range from the usual 36 to 48-volt battery packs. This is why most eBike manufacturers have switched to using brushless motors.

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Controllers for Brushless Motors

Most electric bicycles use brushless DC motors. These require the use of a brushless motor controller. They can rely on internal sensors in the motor in order to know the motor’s rotational speed or operate based on feedback in the power wires.

Sensored vs Sensorless Controllers

If your eBike conversion kit has a motor that includes Hall sensors, you have the option of using a sensored or sensorless speed controller. If you have a sensorless motor, you’ll need to use a brushless motor controller that supports a sensorless operation. Check the product description of your motor first, if available. If not, or if you can’t find answers in product info, look for the number of wires on the motor. A motor with sensors will usually have three to five additional wires along with its wire throttle connector.

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Direct Drive Motors vs Geared Motors

Direct drive motors may require a higher current controller than would be needed with a geared motor delivering similar peak output watts. This is because direct drive motors use high starting torque, meaning a higher amp peak controller will be needed in order to prevent controller damage. Geared motors will run at a higher voltage, however.

Voltage and Current

Besides matching the motor speed controller to the type of motor used in your eBike conversion kit, it’s essential to make sure the electric bike brushless motor controller works with the continuous power and amp requirements of the motor and battery system. A 36 volt, 500-watt peak motor will require a controller with a 14 amp capacity.

Additional Motor Speed Controller Options

Modern eBike motor speed controller designs allow for precise speed control and low noise. A sine wave type electric scooter controller provides smooth starts and reduces torque ripple.

Variable Assist

Commonly available 36V 500W electric bike motor controllers have connectors for throttle and speed sensor wires and are able to provide smooth acceleration and offer multiple modes of pedal assist. If you want options like a display that shows speed, voltage, and power assist level, make sure the motor speed controller has the appropriate wiring and connectors.

Speed Control

Some electric bicycles allow you to set speed limits when using throttle assist. This is usually accomplished through the motor speed controller programming. There are sophisticated controllers that provide CAN Bus data so you can use a display to show power level, battery voltage, speed, and estimated range remaining.

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Throttles and Brake Energy Regeneration

If your motor and drive gearing permits it, some electric scooter speed controller and eBike controller systems let the motor work as a generator when you’re slowing down or going downhill. This can extend the range in some areas by up to 10 percent.

STAT:

MOSFETs such as are used in eBike motor speed controllers are the most produced semiconductor device in the world.

By 2009 there were over 200,000 eBikes in operation in the United States.

Sources:

https://en.wikipedia.org/wiki/Power_semiconductor_device

“Article 430 Motors, Motor Circuits and Controllers”

“Power MOSFET Basics”

Krishnan, Ramu. (2001). Electric Motor Drives: Modeling, Analysis, and Control.

Characterization of Small DC Brushed and Brushless Motorsapps.dtic.mil › dtic › fulltext

Select Controllers for Your eBike FAQ

How can you best use power ratings?

Power ratings in watts can be a useful, if not an exact, guide to motor performance. Make sure to check product specifications carefully, as some electric motors list input watts, while some list rated voltage and current. A continuous output in watts will in general be anywhere from 70-80 percent of the input watts. A 500-Watt continuous rating is a good mid-level motor for an eBike.

How fast does a 500W EBike go?

Depending on rider weight and bike design, a 500-watt eBike can typically cruise at up to about 20 mph. Using a combination of motor and pedaling, some riders may be able to go significantly faster, however.

Can a 36V controller handle 48 volts?

Most 36V controllers may have protective circuits and be able to limit the voltage, meaning that most of the time this won’t be a problem; however, you should never use a controller rated for fewer volts than your battery pack voltage and motor operating voltage, as this creates the possibility of overcurrent and overheating which can cause controller damage. Also, your motor may not reach its rated output.

Ryan Mcbride

Ryan McBride is a writer based in Los Angeles. He has contributed work to magazines and sites including Gayot, Spy, Paper, Ladygunn, 3AM and the Crab Creek Review. He writes consumer reviews, essays, science and tech journalism as well as literary and art criticism.

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