At first glance, electric bicycles seem really simple. You sit on it, turn the throttle and zip off into the distance with a smile on your face. But underneath the hood, so to speak, there’s actually some pretty important physics going on that affect how your ebike works. Most people are oblivious to all the energy conversions and power consumption happening during a ride. By installing a Cycle Analyst or wattmeter on your ebike, you have a window to the inner workings of your machine. What are Cycle Analysts and wattmeters used for? Well, for starters they do a lot more than just measuring your watts, or instantaneous power usage. Let’s take a look at a few of the most important things a good wattmeter will inform you of during a ride.
Wattmeters measure battery consumption
A wattmeter can act like a fuel gauge for your battery. Forget those dinky little green/yellow/red LEDs on your throttle – those are crap. A wattmeter can tell you down to the decimal exactly how much of your battery’s capacity you’ve used. It constantly monitors the current flowing between your battery and controller to count the amp-hours (AH) you’ve used since your last reset. All you need to know is the actual total capacity of your battery and the Cycle Analyst or wattmeter will do the rest. If you’ve got a 12AH battery and your wattmeter is showing a consumption of 10.83 AH, it’s time to start looking for an outlet!
Know your speed and distance
Sure, you can get a bicycle computer to track your speed and distance, but then you’ve just got one more accessory cluttering up your handlebars. If you’ve already got the display of your wattmeter, why not use it to it’s full potential? Wattmeters like the Cycle Analyst are great for this because they can monitor speed and distance either through a magnetic spoke sensor or through a sensor built into the motor itself. Some cheaper wattmeters won’t be able to track distance or speed, they’ll only be able to track your electronic information. With a cheaper wattmeter you’ll be stuck needing to use a cycle computer to track your speed and distance.
Keep tabs on your instantaneous current and power
This is what most people think a wattmeter is for, measuring instantaneous current or watts. This tells you exactly how much power your battery is supplying at any given moment. One of the best ways to use this feature is to train your driving behavior to achieve better range. You’ll quickly see that acceleration and hill climbing cause the power levels to spike, while cruising at full speed on flat ground uses comparatively little power. As you accelerate, you can test different amounts of acceleration and watch how your power levels rise. By easing onto the throttle and taking a few more seconds to accelerate from a complete stop you can dramatically reduce your current levels and save more battery for a longer range.
Determine your efficiency
A good wattmeter will measure of your efficiency, and show you overall how efficiently your electric bicycle is working. A cargo ebike or super powerful ebike might use more than 50 Wh/mile while a lighter and more efficient ebike can use as little as 10-15 Wh/mi. The lower your Wh/mi figure, the longer your battery will last and the farther you can go. By trying different riding styles you can check your Wh/mi data at the end of a ride and see what effect you’ve had on your range. Some people get a bit carried away with efficiency and try to see how far they can extend their range by riding more efficiently. Things like dropping your top speed, accelerating slower and coasting to a stop can all help increase your efficiency. The king of efficiency increases on an electric bicycle will always be pedaling. With light throttle and moderate pedaling, I can push my theoretical range of my ebike to over 200 miles on a 720 watt-hour battery.
Keep track of your battery cycles
The Cycle Analyst tracks the number of reset cycles it has undergone. If you reset your Cycle Analyst every time you have fully charged your ebike, which you should do to ensure accurate battery consumption figures, then you can use this statistic to know exactly how many times you’ve charged your battery over the lifetime of your electric bicycle. This can be useful in determining the remaining lifespan of your battery as well as tracking your own ebike usage. Plus if you ever want to sell your battery and upgrade to better one, it helps to be able to say something like “The battery is in great condition, it’s only got 63 and a half charge cycles on it!” Another feature on the Cycle Analyst includes a lifetime tracking of the total distance you’ve traveled and the total AH of battery you’ve used. This a really interesting statistic, especially if you use your ebike often. You’ll find it thrilling as you pass your first few thousand mi/km increment milestones. The total AH used of your battery is another good way to keep track of the life remaining in your battery, as well get an indication of the average efficiency of your bike over its entire lifetime.
Wattmeters are a valuable part of any ebike
All of this information is helpful in learning about and better understanding your electric bicycle. While you can certainly get by without knowing any of these figures, by being aware of what is happening inside your ebike, you can train yourself to be a better rider. And by keeping an eye on the performance of your ebike over time, you are much more likely to see changes in performance statistics that indicate a looming problem down the road. The more you know, the better prepared you are! photo credit 1, 2