What about a mechanical hand-crank or foot-treadle system with a flywheel? Get 'er goin and then every few min. a couple pumps on the crank to keep the flywheel up to the desired speed.
Josh On Thu, Aug 30, 2012 at 9:42 AM, Phil Hughes <[email protected]> wrote: > Let me toss in a few more factoids. > http://www.batteryspace.com/li-ioncylindricalcellseries.aspx will give > you a decent sample of the common LiION cells. The most common size in > laptop batteries is the 18650 which is typically from 2.2 to 2.78Ah. When > you see a laptop with a higher capacity battery it is typically cells in > series-parallel. For example, a 6-cell battery is generally two strings of > three 18650 cells in parallel. > > The explosing fist is real. The good news is that there are very > inexpensive chips designed to charge these cells. You will find one (for a > single cell) in all cellular phones. They will deal with maximum voltage > and maximum charge current. They are also low drop-out as a typical use is > to output 4.2V from a USB (5V) supply. > > In a typical laptop, you find other chips (generally more than just a > single component) to charge the "almost 12V" string of LiIon cells from the > typical 16 to 20V AC adapter. The disadvantage here is that you need to > monitor the voltages of each cell in the string. Not complicated but that > is what makes the 12V solution potentially more expensive than the 3.7V one. > > A 5V fan is an interesting possibility. First, if may operate fast enough > from say 3.5V so a single LiIon cell would handle it. If not, a flyback > converter to step up 3.7 to 5V would be cheap and high efficiency (because > most of the power comes directly from the battery rather than needing to be > "converted"). > > > On Thu, Aug 30, 2012 at 9:36 AM, Frans Peeters <[email protected]>wrote: > >> Phil, >> >> 3x LiION =3,7Vx3=11,1V Charger needs 4,2x3=12,6 maximum or EXPLOSION >> RISK >> 2W motor at 12V-------->0,1666 A >> 8h xO,166A =1,8Ah >> Laptop cells are 3,6 Ah and more >> Sun cell 15,6V---------> 12,6 V +3V for charging regulator LM317 >> >> PC uP fans exist at 5V x0,2A=1W you could power with 2 cells; >> Also a dual fan of 2x 1W >> >> Regards >> Frans >> >> I see Paul Oliver's work to be excellent and appreciate how a variable >> speed >> fan can offer excellent control over TLUD operation. My reservation is >> that >> there are many places where even the small power requirement (Paul says >> 1-2 >> watts) just isn't available. Lots of people here in Nicaragua are totally >> off-grid and don't have reasonable access to a way to charge a battery. >> So, >> I am been thinking about options. Being, among other things, an >> electronics >> geek, here is what I have been thinking about. >> >> >> Running the TLUD 8 hours a day at "average" fan speed means 12 watts per >> day. At 12 volts that's one ampere hour. I have been thinking about a >> couple >> of approaches. One is "higher tech" but may be a better solution at an >> equivalent or lower cost. In both cases I am just thinking of a >> photovoltaic >> panel to charge the battery. The difference is the battery voltage. >> >> Small PV panels are pretty common on the surplus market. For example, >> Electronic Gold Mine (http://www.goldmine-elec.com/) offers an >> assortment. >> The specifications vary from 7 to 35 volts open circuit with output power >> in >> the range of 1-3 watts. Prices are from $4.50 to $15. As this is quantity >> one retail price information, it is likely the could be found at >> significantly lower costs. >> >> >> As any PV-based system will need some sort of charge controller for the >> battery and what PV cells (in particular, what voltage) will be available >> at >> the best price point, I am thinking that using a single-cell Lithium Ion >> battery (3.7 volts nominal) would make the most sense. Units with a >> capacity >> of 2.2 ampere hours and more are commonly used in laptop computers. They >> offer reasonable life, low cost and the possibility of finding them on the >> surplus market. The cells can be paralleled if higher capacity is needed. >> >> A switching "up-converter" would be needed to supply the 12 volts needed >> for >> the fan. The speed control could be incorporated into the up converter >> which >> would reduce the cost and increase the efficiency. >> >> The alternative would be to use a more or less 12 volt battery (three >> Li-Ion >> cells in series) so that the up-converter could be eliminated. My initial >> guess is that the reduced electronics cost would not be as much as the >> increased battery cost but it is a viable alternative as long as higher >> voltage surplus PV panels are available. >> >> While this sounds like a lot of electronics, this is all very common stuff >> that you find in, for example, cellular phones. There is some design work >> needed but the actual component costs will be very low. >> >> Comments? >> >> -- >> Phil Hughes >> [email protected] >> >> >> >> >> >> >> >> _______________________________________________ >> Stoves mailing list >> >> to Send a Message to the list, use the email address >> [email protected] >> >> to UNSUBSCRIBE or Change your List Settings use the web page >> >> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org >> >> for more Biomass Cooking Stoves, News and Information see our web site: >> http://www.bioenergylists.org/ >> >> > > > -- > Phil Hughes > [email protected] > > > > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > > -- Josh Kearns PhD Candidate Environmental Engineering Engineering for Developing Communities University of Colorado-Boulder Director of Science Aqueous Solutions www.aqsolutions.org Mobile: 720 989 3959 Skype: joshkearns
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