Learning the terminology helps understand the vehicle better
When it comes to light electric vehicles like e-bikes, e-scooters and e-mopeds, there are many terms you may not be familiar with. Don’t worry, it’s perfectly understandable given the technology is new and most people haven’t had to learn this type of terminology with bicycles, scooters or mopeds before.
We will guide you through some of the most common technical terms that we get questions about. If you have any questions that we don’t cover here, feel free to send us a message over live chat.
An electric motor, regardless of its intended usage on an electric bike, e-scooter or e-moped, is a machine that converts electrical energy into mechanical energy in order to provide rotational movement.
As you can see in the image, on the input side there are volts and amps, which are directly supplied from the battery. Similarly, on the output side, there are rotational speed and torque, which serve to move the e-bike forward.
Power and Torque
Torque (measured in N-m or lb-ft)is a rotational force provided directly from the motor to drive the wheels. On the other hand, power (measured in W or HP) is the rate at which this rotational force is generated. Basically, it means how fast the motor can keep producing that torque:
Power (P)= Torque (T) * Rotational Speed (w)
Speed rating comes fixed with the motor, but torque can be multiplied by gear systems.
For simplicity, the higher the torque the higher the force LEVs can use to either pull/withstand a load or accelerate with. This is true given that torque is defined as force x distance.
Another way to understand the power and torque dynamic is by twisting off a screwdriver to loosen a screw. When you are using all your strength to loosen the screw, you are applying torque, regardless of whether or not the screw loosens.
On the contrary, power only exists with movement. Therefore, you need torque to loosen the screw first, and then you can apply power with your hand to keep turning the screwdriver until removing the loosened screw quickly.
In your e-bike, e-scooter or e-moped, you will need higher torque to ride through hilly roads, to climb steep mountain hills or to carry heavy cargo. Similarly, you will need higher power to sustain that high torque requirement if that is your need.
Batteries are the source of energy needed by the electric motor. They are usually rated in voltage and amps.
An amp refers to the electrical current, or flow. In other words, it’s how much power is moving through the battery.
Imagine volts as the “force” pushing amps through the battery. The higher the voltage, the more energy can be moved, or the faster it can be moved. So, a higher voltage battery can force more energy from the battery through the motor. Keeping all constant/fixed, a higher voltage system will help motor to deliver more torque for quicker acceleration, but it will discharge the battery faster.
Watts are a measurement/unit of power. In a battery, they can be calculated as follow:
Power (P)= Volts(V)* Amps (A)
i.e. A 12-48V battery can produce 576 Watts of Power.
Amp-Hours (Ah) represent the battery capacity. Technically, it means how much current (Amps) the battery can deliver in one hour at a given voltage. For example, a 12Ah-48V battery will provide 12 amps for one hour at 48 volts. Or 6 amps for 2 hours, etc.
One of the most commonly listed specs for batteries, Watt-Hours are the number of watts that can be delivered in one hour by the battery. Using the 12Ah-48V example above, you’d have a 576 Wh battery. If that battery is coupled with a 576W motor, which is performing at its highest level of assist output, the result would be around one hour of usage before the battery runs out.
On the other hand, if the motor is only demanded at half of its maximum power (285W) by using a lower level of pedal assist, for example, the result now would be two hours of vehicle usage, and so on.
Therefore, watt hours are the most useful spec in determining an LEV real range or run time, assuming the motor watt rating is known.
In conclusion, given that most systems today are standardized, when trying to maximize total range, or time before recharging the battery, the best course of action is to look for a battery with high watt-hour (WH) rating.