Step up and get your own "dynamo hum"...(FZ).  All jokes aside, its a simple dynamo light mounted to a Planet Bike light bracket.  On about 6 cranks I get 20 to 25 minutes of light.
  There is a 3.6 volt NiMH rechargeable battery that comes in the light.  SO, by free I refer to your out of pocket cost on batteries.

Step 1: material

1. dynamo light....Harbor Freight, 2 for $8.
2. quick release light strap...most have a screw to change the mounting base, this is a Planet Bike
3. super glue
4. fingernail polish remover........or acetone

i like it. This is going on my bike very soon
back @ you man!
No no no, you see, its a dynamo-charged rechargeable battery, so you do not need to replace them.  Just crank the dynamo to recharge the internal batteries.  This is pretty cool, now imagine if you attached a cable from the dynamo to your wheel!  (hands free charging)!!
Yeah, then you just have a normal light like found on about every bike. 
but the battery lasts soooo much longer.
Tadah!&nbsp;You made a conventional dynamo light!&nbsp;Brilliant!&nbsp;How come nobody has evyer thought of that before?<br /> <br /> Oh....<br /> <br /> Wait.<br />
Good instructable . Good not to have to worry about your batteries dieing on your ride . I do recommend having a cheap red blinky light for the rear it be seen&nbsp;much better then a reflector . In the same vein lights or reflectors on pedals make you much easier to see also .
NICE, anything not to purchase batteries!<br />
Yeah, um these do have batteries, they just recharge.
Are you positive?&nbsp; I was told it was a capacitor.<br /> Of course I may be wrong, and that's cool.<br />
Yes, I've taken apart 10 or so of that kind of light. Each of them had lithium ion button cells.
Yes, you are correct.&nbsp; <br /> Since it was featured,&nbsp; I'm not going to edit it.<br /> <br />
It doesn't bother me if you edit it or not, I just like solving little misunderstandings and helping people understand how things work.&nbsp;
&nbsp; I thank you because I learned more about it......I went ahead and edited it anyways because it was wrong.&nbsp; I'm also new here and thought I could not edit once it had been featured.<br /> &nbsp; Stay on point, please.&nbsp; I WILL do more stupid stuff in &quot;public&quot;!<br />
Awww!<br /> I was hoping it would charge via the pedals or wheels...<br />
<span class="medium_text" id="result_box"><span title="Sea como sea, con o sin bater&iacute;a, es un excelente instructable.">Anyway, with or without battery, is an excellent instructable. </span><span title="Y si hay bater&iacute;a, pero se carga a mano, bienvenida sea.">And if there are&nbsp;</span></span><span class="medium_text" id="result_box"><span title="Sea como sea, con o sin bater&iacute;a, es un excelente instructable."> batteries</span></span><span class="medium_text" id="result_box"><span title="Y si hay bater&iacute;a, pero se carga a mano, bienvenida sea.">, but they are loaded by hand, are welcome.</span></span>
hold it <br /> so this is a<span class="stepTitle"> &quot;Battery free bike light</span>&quot; <br /> with a Battery in it ??????<br />
I'm no tech, but I do believe that the dynamo charges a capacitor.<br /> In the picture you can see it in blue shrink&nbsp; wrap.&nbsp; <br />
Why would they shrink wrap a capacitor? I bet that you can see a line sticking up from one end to the other, which is a wire underneath. I can almost guarantee that if you rip/cut that open there will be button cell batteries.
i agree, i know he probably means no batteries needed to be inserted, and i understand that that doesnt fit in the title, but its also kind of deceiving...<br /> <br /> but its a nice idea, nice instructable, and it works pretty good i think ;)<br />

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