How to Actually Use a Human-Powered Generator to Charge Your Phone


In an age of increasing reliance on technology, keeping our phones charged can be a challenge when we're off the grid. However, with some simple tools, we can harness the power of human energy to generate electricity and keep our devices going. In this article, I'll provide an in-depth guide on how to build and use a human-powered generator to charge a phone.

Understanding Human-Powered Electricity Generation

Human beings have been using our physical exertion to perform work and generate power for millennia. The same principles that allow us to pump water, mill grain, or propel a bike can be applied on a small scale to produce electricity.

Human-powered generators convert the mechanical power from physical effort into electrical energy. The key components are:

With a properly designed generator, around 50 watts of electricity can be produced from a moderate pedaling or cranking pace - enough to charge a smartphone in about an hour of human power.

Choosing a Generator Design

There are a few common options for human-powered generator designs:

Pedal Powered

Hand Crank Generators

Linear Motion Generators

For charging a phone, a pedal or hand crank generator are the most efficient choices. Linear types may take a very long time to generate usable electricity.

Building a Pedal Powered Generator

If you're reasonably handy, constructing a pedal powered generator from bicycles parts is straightforward. Here's what you'll need:

And the basic assembly process:

  1. Mount the motor in place of the bike's rear wheel. Connect it to the bike chainring.
  2. Wire the motor directly to a voltage regulator. Use sufficient gauge wiring.
  3. Connect the regulator to your battery pack to store energy. Charge controller optional.
  4. Install a phone cradle, or USB charging port wired to the batteries.

Now pedaling the bike will spin the motor instead of the wheel, generating about 100 watts of power!

Tips for Building a Pedal Generator

Using Your Generator

Once built, using your human powered generator is straightforward:

  1. With batteries fully charged, pedal the bike at a steady, moderate pace. Faster pedaling produces more electricity.

  2. Monitor your phone while pedaling. Once the battery indicator shows charging, you've successfully powered up the generator.

  3. Continue pedaling steadily to charge the phone. You'll need about 1 hour of total pedaling to fully charge most phones.

  4. Take occasional breaks if you get tired. The batteries will continue powering the phone when you stop pedaling.

  5. Recharge the batteries by pedaling again once your phone and the generator batteries are depleted.

Maximizing Efficiency

Here are some tips to maximize your pedal generator's efficiency and convenience:


Generating electricity from human power requires a bit of effort, but can be very rewarding and enable you to keep devices charged anywhere. With some DIY skills and elbow grease, building and using a pedal powered generator is definitely achievable. The exercise doesn't hurt either! Start pedaling and harness clean renewable energy straight from your own body.