Phil,
Thank you for your excellent comments. I am not an electronics guy, so
I will trust in what you say until others might find issues to discuss.
How can we proceed? You are in Nicaragua, right?
As soon as I have some few units from Paul O., we can do some trials.
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 8/30/2012 9:13 AM, Phil Hughes wrote:
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] <mailto:[email protected]>
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