It would make sense that you could charge an electric bike when going downhill or when applying the brakes, but the truth is that the power you’d get back does not make up for the loss in distance and speed.
The vast majority of electric bikes on the market will not charge when going downhill or braking. There are some that do, but it is rare and more of a sales gimmick.
I get asked all the time at the bike shop about whether an ebike will charge while you are riding it and it’s a good question.
The fact is, that even though the technology is available to do this, in practical use it just doesn’t work effectively.
Electric bikes are designed to store the electricity from being plugged in and power the motor to transfer that to you as you are riding.
Why Don’t Electric Bikes Charge When Going Downhill?
It is mainly because the amount of electricity you would be able to generate and return to the battery does not make up for the amount of resistance and energy from you, required to produce it.
In order to to create enough charge to allow the battery to actually gain power, creates a lot of friction and this, in turn, will slow you down. So much so that you would have to pedal pretty hard even when you are going downhill.
So if it takes you pedaling a mile-long downhill (which is a pretty long downhill) to recharge enough energy to go a tenth of a mile further at the end of your ride, you would probably get the same if you just coasted down the hill without peddling and saved your own energy.
Do Electric Bikes Charge When Pedaling?
No, they don’t. Electric bike motors are helping assist you when you are pedaling and therefore using energy not charging it up.
Some stationary bikes at the gym can be operated without being plugged by receiving a charge when you begin to pedal.
This would seem like a great way for you to pedal some power back into your battery on an ebike.
The difference is that the stationary bike at the gym is not moving and you only need to supply enough energy to it to power some basic circuitry for the bike to work.
An ebike on the other hand requires far more energy in order to power the motor and actually help assist you in propelling the ebike forward. That’s why they have big heavy batteries.
I used to work for ZAP! Back in 1999, a company that built motor kits for bikes. These motors were rollers that would engage the rear bike tire and spin it forward.
You could lock the roller down onto the tire and pedal to charge the battery, but it felt like riding a stationary bike at the highest setting. It just wasn’t practical.
It would feel like you were peddling with the brakes on and that is the opposite of what riding an ebike is supposed to be like.
Ebikes make it feel like you have super-powered legs, not like you are riding through jello.
Can I Charge My Electric Bike by Pedaling Stationary?
No, they don’t, but this would seem like an excellent solution to allow you to regenerate your ebike battery, maybe while out camping or something.
However, I will give you an idea of what would be like if you tried it.
Below is my Bosch data from my average morning commute –
You can see in the right-hand column, 3rd row down is how many watts I am producing per hour. Both rides are about a half-hour long.
Directly to the left of the watts is how many calories I burned. (riding an ebike really burns calories!) Calories are basically a measurement of how much energy I used.
In the top ride, I was producing 154 watts per hour and burned 269 calories in about half an hour, so burning about 538 cal/hr.
In the bottom ride, I produced 125 watts/hr and burned about 416 cal/hr. Every ride will vary a bit with hills and wind.
I averaged about 140 watts/hr for 477 cal/hr. Sorry about all the math, but stick with me 🙂
Keeping in mind this was about an hour-long ride total with a rest break in the middle. So a longer ride would see these numbers begin to fall.
Now, my ebike battery holds 500 watt-hours of juice. In order for me to fully charge my ebike battery, I would have to pedal at the same pace as this ride for 3.5 hours straight, without slowing down, and I’d burn 1,670 calories in the process.
- Talk about a workout!
This would all have to be done after riding the ebike long enough to deplete the battery. (about 30 to 50 miles)
This is just not a practical way to charge the bike. I’ll just plug it in.
Do Electric Bikes Have Regenerative Braking?
Some do, but you will notice it. What regenerative braking is, is when you get your ebike up to a certain speed and lightly apply the brakes, the motor will now use your inertia to re-supply the battery with a small amount of charge through the motor.
This can only work on direct-drive hub motors which are simply not as good as geared hub motors and mid-drive ebikes don’t have this feature. Direct drive motors are bigger and heavier than geared hub motors and not used as much.
It makes it so that if you’re on an ebike that has the motor stop assisting you at 20mph and you can exceed 20mph, then you can lightly apply your brake levers and you’ll feel the bike slowing down as energy is returned to your battery.
The problem with this is that you would be having a more efficient ride if the motor just completely disengages and allow you to coast freely or even keep pedaling on your own and maintain your speed.
The only free power for an ebike is from the sun, but that also comes with its limits. Stay tuned for an entire section about Pedaling With Solar Power!
Which Ebikes CAN Charge While You Are Riding?
If you still want to try out an electric bike with regenerative braking there are some models available in the US. I would just avoid them.
https://www.radpowerbikes.com/
These 3 Models –
- RadCity 4
- Rad Wagon 4
- RadCity Step-thru 3
There may be a couple of others that nobody has heard of, but that’s about it for the US. If you really want a Rad Power Bike I would suggest one of their models with a geared hub drive motor. These will not have regenerative braking but ride a lot smoother and the motors weigh less.
At the End of the Day
Electric bikes can go pretty far these days on a single charge and you can always carry an extra battery to double your range.
Trying to resupply the power to the battery as you are riding, will only make the bike slower and harder to ride.
If this technology really worked well, trust me, every single ebike manufacturer would have it on all their bikes and it would be the first line on the sales page!
The whole point of riding an ebike is that it’s easier and more fun. Just be sure to charge up your ebike before you go for a ride and know how much range you can get on your specific bike.
As always stay safe out there and Keep on Riding!