[Stoves] Powering a TLUD Fan

[Josh Kearns]

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 <nicafyl at gmail.com> 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 <peetersfrans at telenet.be>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
>> nicafyl at gmail.com
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> Stoves mailing list
>>
>> to Send a Message to the list, use the email address
>> stoves at lists.bioenergylists.org
>>
>> 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
> nicafyl at gmail.com
>
>
>
>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20120830/9ccaa442/attachment.html>