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Nick Kidd, from Copycat Photographic, had a clever concept: A product which would allow a bicycle dynamo to recharge mobile phones, GPS units and MP3 players while riding. He asked DFAD to design a product which would achieve this, and created a new company, PedalPower+, around this product.

The challenges:

The AC output voltage and power from a bicycle dynamo varies widely with speed. Although the available power at normal riding speeds is relatively low, dynamos are capable of developing dangerously high voltages at high speeds.

An AC-DC converter/regulator for bicycle duty must be able to:

  • Develop useable output power at low riding speeds;
  • Protect itself against prolonged high input voltages at high riding speeds;
  • Convert the riders’ muscle power into useable electrical power with high efficiency;
  • Protect itself against output overloads;
  • Cope with adverse environments – temperature extremes, rain and frost;
  • Be affordable!

The Solution:

DFAD developed an inline AC-DC converter which provides a 5V regulated output over a large range of dynamo speeds, with very high conversion efficiency. The converter features an innovative circuit which protects the converter against high dynamo voltages without imposing any additional drag on the rider.

In order to optimise the converters’ performance, we constructed a rolling-wheel test jig which allowed us to accurately characterise a variety of dynamos over a wide range of speeds.

The inline converter cable has undergone extensive testing – including an endurance run equivalent to two circumnavigations of the equator – and is now in full production.

Building on the success of this product, PedalPower+ has introduced a number of associated products including battery storage systems to harvest dynamo power for later use, handlebar clamping systems for the riders’ appliances and connectors to suit a wide range of appliances.

From experience gained in the development of the inline AC-DC converter, we have recently finalised the design of another very exciting product. We have integrated the converter circuit into the dynamo body, to create the world’s first dynamo with regulated DC output!

These center-hub dynamos are the “holy grail” for cyclists who require power on the move, since they have very low rolling resistance and a very stable output power but require no additional wiring or attachments to their bicycle.

Also in development are traditional rim-driven “bottle” dynamos fitted with integrated DC conversion, which will find application where low cost is more critical than low rolling resistance.

For testimonials, contact Nick Kidd from PedalPower+ at:
And visit: []

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