This is Part 3 in our Understanding Electric Bike Batteries Series. In this lesson we learn the difference between high energy and high power batteries and why electric bikes need high energy batteries. In Lesson 1 we learned how energy is measured in watt-hrs and this is the like the size of the gas tank. In Lesson 2 we learned how batteries are rated in watt-hrs, which is amp-hrs X voltage of the battery.
Electric Bicycles Need High Energy Batteries, Not High Power Energy is the amount of power used over time. An electric bicycle must be more efficient with the use of energy than a gas car. With an electric bike, a battery with high-energy, not high power is preferred. This gives the vehicle the ability to travel long distances.
Some batteries put out a large amount of power, but they don’t have very much energy (they have low watt hrs). That means the vehicle will accelerate very quickly, like a high horsepower Corvette, but will not go very far, because the size of the gas tank is small (low watt-hrs).
Electric Cars and Bikes Have Different Needs In hybrid cars, where the engine is constantly filling the battery, power density is more important than energy density. The high power density lets the gas motor recharge the battery quickly. The gasoline in the hybrid car is providing the energy, not the battery. Even though the electric bike is a hybrid between the human and the electric motor, it is not like a Prius in power needs.
In the electric bike, the person and the battery are both contributing energy and the battery is not re-filled by the rider. This requires a high-energy battery for an electric bike.
All electric bicycles are charged like a laptop, with a wall charger. You could charge the battery by peddling, but that would defeat the purpose of the electric bicycle. If you had to peddle to fill the battery, you’d be using all your energy to fill the battery and you wouldn’t get any boost to your speed or range.
To learn more about electric bikes and the e-bikes Optibike currently offers, contact us at 303-443-0932. And follow us on Facebook, Twitter, and our E Bike Blog, to learn more about the benefits of electric bikes.
Excerpted from “The Electric Bike cBook” by Jim Turner. Available FREE on I Pad and Kindle. 
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