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Minty...Spinny Boost
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Please be positive and constructive with your questions and comments.

Minty...Spinny Boost

by Snipeye on Tue Aug 31, 2010 11:30 pm

Perhaps this belongs in the mintyboost section, but strictly speaking, it's not mintyboost.

I'm starting design on a bike-USB charger kit. This includes several things:

1. Permanent magnet motor spinning off tire
2. Ultracap bank receiving juice from the motor.
3. Mintyboost-like product taking X volts from the ultracaps (haven't made the bank yet, don't know what specs will be) and makes it 5v.


A few problems:

1. I don't know what motor to use. I've heard a little about dynamo, but I was hoping some people had other suggestions for me to research and find out about.

2. I know so close to nothing about ultracaps, it's not even funny. I couldn't find a tutorial on making a bank, or anything, however - if somebody could point me toward a guide, or an information page about ultracaps, that'd be nice.

2a. Can ultracaps take lower voltage and output higher? I.E., when the bike goes slower, it won't produce very many volts - can the ultracap take what it can give, and put out X volts (which may be higher than the input) anyway? - this is probably answered in a guide somewhere, but once again, I've got no idea where one is.

3. Fortunately, not too many problems with a mintyboost-esque product. I learned my way around this more or less. Any suggestions for an enclosure? The closer to the seat it can be (so things can charge in your pocket, etc, or maybe a holding-box to charge stuff in) the better.
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Re: Minty...Spinny Boost

by zener on Wed Sep 01, 2010 12:05 am


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Re: Minty...Spinny Boost

by Entropy on Fri Sep 03, 2010 12:50 pm

Ultracaps are just like regular caps, except:
1) They have much higher ESR (equivalent series resistance) than normal caps - When charging off of a bike motor this doesn't really matter.
2) They have much higher capacitance per unit volume/weight than normal caps
3) They typically have very low maximum voltage ratings. Single ultracaps are typically rated only around 2.5 volts, so being able to handle higher voltages requires multiple in series.

I think someone did something exactly like what you're describing over on instructables... Generator feeds ultracap, ultracap feeds mintyboost.

However you may seriously want to consider some sort of the charge controller for the ultracap - if it's fully discharged, it'll be difficult to get the bike wheels spinning unless you have some sort of current limiter.
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Please be positive and constructive with your questions and comments.