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Is this a capacitor or a battery? Answered

In regards to my "battery free bike light".
  I was told that a dynamo flashlight charges a capacitor.  Is this the case?
Take a look,
Thanks

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frollardBest Answer (author)2010-03-07

I would be inclined to believe its a small nicad battery - anything but a supercap at that size would light an led for mere seconds, where these generally run for a few minutes.

As kiteman says - its mostly dependent on runtime.  Less than a minute is probably a cap.
cutting off the shrinkwrap will likely yield a result.

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Re-design (author)frollard2010-03-07

I vote nicad also.  Recently I took apart a crank radio that had a very similar nicad battery in it, except no shrink wrap.

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frollard (author)Re-design2010-03-07

Although, rereading the title "battery free bike light" could mean there is no user provided batteries...or that it truly has no batteries total :S

Damn marketing fuzz.

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onrust (author)frollard2010-03-07

That is my instructable title!
The instructable has been featured as well and "battery free" is up for question.

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frollard (author)onrust2010-03-07

Title is fine - just need to include a little disclaimer that its a semantic argument on what a flashlight having a battery actually means - in this case, you don't have to supply any AA's or anything.

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smitec08 (author)frollard2010-03-07

+1

its a 3.6V NiMH battery, well as long as its the same one from the instructable.

Also apparently only has a 500 charge life cycle.

see here: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=65207

Hope that helps

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onrust (author)smitec082010-03-07

  Yes, it seems I'm getting a bit of criticism about my title.  Since the instructable was featured I'm not going to edit it.
  Thanks for the info.   I am most interested to see how long I get out of a "500" charge life cycle. 

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Kiteman (author)2010-03-07

From the proportions, probably a capacitor.

If it charges to maximum brightness quickly, and if the maximum brightness does not not last a huge length of time, then it is probably a capacitor.

If you don't want to cut the heatshrink off it, try charging it up and then shorting out the connections with a piece of wire - if you get a crack and a spark, it's a capacitor...

...and you may just have wrecked it...

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