Understanding Watts, Volts, and Amps in E-Bikes

Happy Octoburrrrrr folks! We have now reached the off-season for bike-riding but that does not stop us or the new innovations in electric bike technology. We have many new electric vehicles in the making and are making BIG plans to accommodate it... stay tuned!

We are noticing that many folks around our neighborhood find it difficult when they wrap their minds around the concept behind electric bikes. Our savvy new Service Technician on board, Daniel Lauzon, does a fantastic job of explaining how electrical terms for an e-bike is interpreted in the American culture as well as how to do the math yourself, relatively speaking. 

 

"The world of e-bikes can be very confusing to people who are not steeped in it. A slew of words get thrown around with little or no context to understand them. Most commonly, “watts” are used to determine the relative power of an electric system, but to many shoppers it's an arbitrary term. Today I'll be explaining what it means, the terms associated with it, and how you can use it to be smart about your next electric purchase.

Watts are a measure of energy either being produced or consumed. Most e-bikes on the market are equipped with a motor rater to between 250 and 500 watts. This means that, at its expected peak, the motor will convert 250 to 500 watts of energy, in this case electricity, into motion by turning the wheel. For e-bikes, this is used to describe the power of the motor the same way Horsepower is used for a car.

A motor's wattage isn't always useful to determine an e-bikes expected range, however. To estimate that, you need to look at the battery, which has two ratings: “voltage” and “amp-hours”, often abbreviated to “V” and “Ah”. Volts are the amount of stored 'oomph' the battery can hold, or a measurement of potential energy. Amps are a measure of current, best thought of here as how quickly the battery can discharge the volts of potential energy into watts of usable power.

Because an e-bike has a complete system, the amps are measured in hour time frames and marked as “Amp-hours”. This allows you to do the range math: potential power (Volts) multiplied by how fast the battery can discharge that energy (Amp-hours) gives you “Watt-hours”, often abbreviated “Wh”. You can then divide the battery's watt-hours by the wattage of the motor, telling you how many hours the battery can power the motor at the motor's top speed. Multiply that by the top speed in miles per hour, and you have the estimated range in miles!

In the real world, this is much more complicated. A 500 watt motor will often consume up to 750 watts during hard acceleration or trying to maintain top speed up a hill. Often you will be pedaling your e-bike, taking some or all of the load away from the motor, and sometimes you'll be coasting. These things can all shift an e-bike's range to a significant degree from what is listed. Pedal-assist bicycles often have more ranges that are easier to replicate in daily riding because they encourage the rider to pedal, while throttle-based systems can be used at maximum with no immediate consequences.

This explanation is meant to give you a better idea of what the terms and numbers associated with e-bikes mean. The explanations have been simplified significantly so they can be understood more easily and the calculations are rules of thumb rather than rigorous scientific equations. Nevertheless, you can use them for “back-of-the-napkin” math problems and as a way to understand the pros and cons of different e-bikes and their motor systems."

 

Now that we all know how the terminology that makes up an electric bike semi-works, imagine yourself riding an e-bike without having to sweat and conquering that hill at around 4 cents per charge! Equate that into miles per gallon, with the gas price at $4 a gallon at 20 miles a gallon and 20 miles per charge on an electric bike, that would be 2,000 miles per gallon monetarily speaking for the electric bike! This efficient, eco-friendly way of transportation simply puts the cash back in your pocket while giving you an exhilarating and efficient bike ride to wherever you need to go, whenever. 

Have more thoughts or questions about having an electric bike in your life? Call our shop at (206) 344-8000 Tuesday-Saturday 11-6:30 and we'd be happy to assist you through it!

 

Happy (Safe) Riding folks!

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