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I want to build an electric bike using mechanical energy? Answered

Hi all 

I have been given a project that I want to build an electric bicycle such that when i do peddling the mechanical energy converted to electric energy is stored in the battery and when my battery becomes fully charged i don't  need to peddle any more and use the battery and vice versa

Any help ???????




Lets assume your talking about adding a motor and battery pack and generator to a bike. You want to be able to ride the bike and charge the batteries at the same time right? Then when you have enough charge on the battery you'd like to switch over to the motor and ride around like that?

First problem i see is you'll need to pedal the bike around for hours to charge the battery. Then you will only get a fraction of that time riding around on the motor. Next you have the problem of all that added weight. To increase drive time you'll need more batteries which will increase the amount of pedal time needed to charge them.

If you start looking at the projects listed on the right hand side of the screen you'll find all sorts of good ideas for the electrical side of the system. Then all you need is a way to engage the motor and disengage the generator and vise versa. Keep in mind whatever voltage of motor and batteries you use. To charge the batteries you'll need to put more voltage into them than that and the generator you use will have to produce that voltage at low RPMs. Which may require a rather large generator that will be harder to get rotating with a bike.

Yes you understand it right i'll have to overcome the above issues as part of my project. Any links about my project would be great

@rickharris @mpilchfamily: In simple i want to build a hybrid electric bike or electric conversion bike

No such thing unless your making a gassed powered motorcycle into a gas electric hybrid. As for converting an existing bike to electric there are kits available. They come with a new rim for your rear wheel what have the motor built in. They also give you a battery pack and charge controller. Now you may be able to add a setup that will help charge the battery as you pedal along but that will only extend you ride time by minutes at best. You would have to pedal the bike at a constant rate for several hours to get a full charge on the batteries and get a 45 minute ride on the motor.

You need a generator - IF you us a car alternator - (the simple way to go ) you need to turn it at more than 3000RPM to charge a battery.

I suggest your going to need to look at Lithium batteries and using an electric motor as a generator possibly a stepper motor.

You will need some electronics to control the charging and let you know when the battery is charged.

This is a very inefficient way to go - Your peddling anyway and any such system will have losses so some energy is wasted - better to use that wasted energy to peddle with.

Your also adding considerable weight to the bike - something no sensible cyclist would do.

i know what you are saying but i have to complete the project and overcome the weight and other types of issues. I have searched around internet but they are "electric bike generator" that generates mechanical energy and charges batteries, mobile etc. But i need a project that uses mechanical energy that charges the battery and then i drive the bike with charged battery. Simply i want to use my bike or bicycle for dual purposes i.e.

1. When i do peddling i am not only covering the distance but also charging my battery.

2. When the battery is charged i will not have to use my legs to run the bike instead motor and battery does the trick.


You need to know a lot about generating electricity and charging batteries - It's not all that simple.

Is this a personal project or a school project?

You need MUCH more than I can offer here in brief posts - In addition if this is a school project then it is YOUR project so you must do the research and work to get to the final end point.

If it is personal

I can tell you from knowledge and experience that this isn't a good way to go.

Simple calculations as to the effort required to charge a battery to a meaningful level will soon show you that your putting out more effort than you would if you were simply riding the bike.

Look to model aircraft that use electric motors to work. Look at light weight batteries look at ways yo generate the necessary power to charge them - Think about the weight you going to carry.