OK, admittedly that’s a bit harsh, considering it’s a question that I have googled myself. But as I’ve learned more and more about batteries, I’ve come to realize this question really can’t be answered. You can’t think of the capacity of a battery like a tank of gas in a car: while they’re conceptually similar, they’re pretty different. If you’ve asked “what’s the range” and gotten “it depends” as an answer: that really is the answer. Let me try to make this simple so that you can take the most important pieces with you as you compare ebikes and their capabilities.
TL;DR: Compare batteries by Watt-hour (Wh) to normalize their capacity. Realize that range is heavily impacted by weight, terrain, and assist level, and take some time understand your use case when you’re comparing. Capacity does not equal range.
You Need a Battery Glossary
Let’s start with ebike battery and motor terminology explanations for those of us who are normal people. (You already know these things? Cool, skip this section.) When you’re shopping around, comparing the specifications of different ebikes, and trying to answer any kind of range question, you’ll see these measurements used. To be able to really compare, understanding the abbreviations next to the numbers .
- Ah (Amp Hour): Amp-hour (Ah) is a measure of the battery’s capacity. Think of it as the fuel tank for your e-bike.
- V (Volts): Volts (V) determine the strength of the electric flow from the battery to the motor. More volts mean more power over an extended duration.
- Wh (Watt-hour): Watt-hour (Wh) represents your e-bike battery’s total power storage capacity. It factors in voltage and energy capacity. A higher Wh rating equates to a battery with more power.
- Nm (Newton-meters): Torque, measured in Newton-meters (Nm), significantly impacts acceleration and efficiency, especially on hilly terrains.
Look at Watt Hours (Wh)
Watt-hours (Wh) are a good standard for comparing e-bike batteries. They tell you the total power stored in a battery, by considering both voltage and energy capacity. To put it simply, it’s a measure of how much energy your battery can deliver. Batteries can have different combinations of volts and amp-hours, but they can yield a similar Watt-hour rating. A battery with a higher Wh rating is typically the better choice for maximizing range and performance.
Battery Range is a Range
Why is battery range usually represented by a, well, range? (E.g. “15 to 40 miles on a single charge.”) Yes, we’re back to that all important, anxiety-inducing question: “How far can I go on a single charge?” It depends. That’s annoying, I know. Here’s exactly what it depends on:
- How heavy are you, the bike, and the crap you’re carrying with you? If it’s just you on the bike, and the bike itself is lightweight, you’re probably going to get more range.
- How much are you asking your motor to help you? If you + bike + crap = heavy, and you’re going uphill on the highest level of assist, you’re probably going to have a lot less range.
- How efficient is the battery? How powerful is the motor? This is one thing that’s not an “it depends”, but is something you can actually compare between models, taking the first two points into consideration.
Think of your e-bike motor as the speed guru. High-power motors mean you can go fast, but they’re also energy hogs. The secret sauce? Motor Watts matter. Big Watts need more battery voltage, like a sports car needing a bigger gas tank*. Higher voltage batteries (say, 48V) are efficient, needing fewer Amp-hours for the same power. It’s like a fuel-efficient ride, going further without frequent refueling.
*I know I said comparing cars to ebikes isn’t a good idea, but life is filled with contradictions.
Choosing the Right E-Bike Battery
Now, let’s get to the nitty-gritty of choosing the perfect e-bike battery:
- Riding Conditions: The terrain you’ll be tackling matters. Hilly areas demand batteries with higher torque and capacity for maintaining performance.
- Weight: Remember that more weight means more power is needed. A higher-capacity battery can be heavier, and this extra weight will require more energy, affecting your range.
- Riding Style: Your preferred level of assistance is a crucial factor. If you want more power for longer rides, opt for a battery with a higher Wh rating.
- Battery Comparison: When comparing e-bike models, pay close attention to the Wh rating. It provides a standardized way to evaluate the battery’s potential range and performance.
Range Relationship Status: It’s Complicated
Everything in life has trade-offs, and things are rarely simple and straight forward. That’s why there isn’t a simple answer to “how far can I go on a single charge?” But that doesn’t mean you can’t successfully compare different ebike batteries.
Ebike battery range ultimately boils down to two critical factors: weight and terrain. There’s a direct relationship between the weight of your e-bike, including the rider, and the power required to move that weight. Lighter bikes and riders demand less energy to maintain speed, using less power and extending the range. No matter which capacity battery you choose, these key considerations will significantly influence your e-bike’s range.
Unsatisfied with my explanation? Don’t like my dated facebook reference as a heading for a blog post conclusion? Leave a comment. This is probably a good post to update over time, considering it’s everyone’s favorite question about ebikes.