Bike Phone V1.0




Just because you are some bigshot executive, does not mean you drive in comfort to work everyday. For those that lead a hectic life and busy schedule without the luxury of topping up their phone battery via a car cigarette lighter, this should do the job using one of those old dynamo's from the front wheel of a bike.

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Step 1: What You Need

1. bike (not shown) 2. The dynamo for the bike light 3. The light (not compulsory but adds functionality) 4. An old charger, or new. 5. A phone

Something to cut the wire with is usefull to.

Step 2: Mod the Charger

Just clip the wire before the socket part, you wont be sucking power off the grid any more. Then strip the cable a couple of cm to seperate the 2 inner wires.

Step 3: Connect

Depending on your dynamo it may vary on how you connect it but it should be similarly simple as with mine which is just a matter of click , click.

Step 4: Road Ready

just screw everything back on to your ride... and if you want you could clip the wire down with tape or something, as for the light i said its not compulsory but you if you can hollow it out like mine and flip it up you have your phone 'cradle'.

I used a nokia and when charged like this should display something similar to 'optimum charging', i didnt get a chance to try out any other phones.

Remember, dont place a call while on the road, pull over to a safe location.

This is really v1.0, i had nothing around the house, not even masking tape! so watch out for future refinements such as hands free, fax, and the option to keep the light aswell. (yes i know i know "but what about the light?" will be the first question but important people are too busy to get hit by cars.)

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    14 Discussions


    13 years ago

    How well does the phone stay in the holder when the bike goes through a pot hole or over a curb? It appears that the phone might bounce out.

    3 replies
    Stephen Bmwarren_us

    Reply 13 years ago

    Oh its totally unstable, but im thinking about v1.2 allready.. was gonna try to find some foam like the kind you get in a small box when you buy a watch or some other gadget, something like that would be perfect to stuff in the lamp shell and slide the phone into.


    11 years ago on Step 4

    This seems very dangerous, I'm a bit worried about that the dynamo outputs different voltages. I don't know how high it goes though, but wouldn't you have to bike around at one speed all the time to get the phone to charge? Perhaps it works anyway, how have your biking and test turned out?


    11 years ago on Step 4

    looks so simple I am going to rig it up this weekend!

    Leon Close

    13 years ago

    I thought these dynamos produced AC at voltage proportional to speed. I could be wrong but I'm quite sure that Lithium Ion batteries won't like this one bit.

    3 replies
    sofa0neLeon Close

    Reply 13 years ago

    dynamo = A generator, especially one for producing direct current.
    ( )

    Most Li-ion batteries also include special circuitry to protect the battery from damage due to overcharging or undercharging. As a general rule...however voltage should be monitored as well...
    I should also point everyone who is interested in this type of project to check out this link...


    Reply 13 years ago

    Bicycle dynamos are incorrectly named and produce AC not DC.
    A rectifier will solve that problem.

    Not all similar devices are as tolerent as mobile phones. Mobile phones usually share a single mains adapter between a lot of models that often have different battery chemistries. Nokias for instance all share the same charger.
    Similar devices such as mp3 players that are powered by a regulated supply might not fair so well.


    Reply 13 years ago

    I took apart one of my cell phone chargers that died... Nothing special, it just provided a somewhat stable voltage. I assumed that the charging bits are onboard the phone itself which makes sense to me, they'd only have to design one charging circuit and then provide a somewhat "clean" voltage. I say "clean" because when I took apart a car adapter-charger , my voltage signal oscillated. Those things make great drivers for Luxeons with a little modification :P


    13 years ago

    Great Idea! I assume that the original charger output is equal to the dynamo output? What if you used a small battery to store the charge from the dynamo and then charged the cell phone from the battery. This way you don't interrupt the charging cycle when you stop the bike for short periods.

    2 replies
    Stephen Bjoez34

    Reply 13 years ago

    nice idea, im by far no expert but i dont know if it generates enough power to have the ability to store any for later, im not sure though, guess it depends how much of a bad ass you are on your bike :) Otherwise instead of a battery i think it would be some kind of capacitor circuit that some friendly electronics genious on the site could design for us :D


    Reply 13 years ago

    I would look at the charger. It should tell what voltage your phone charges at. Then I would buy a voltage regulator that matches that voltage. Attach the dynamo to the regulator input and then the charger cable to the regulatoroutput. (see make magazine vol 7 pg 137)