Subject:
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Re: MOC: Working solar powered rover and geiger counter
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 8 Feb 2006 05:06:09 GMT
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Viewed:
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1834 times
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In lugnet.robotics, Claude Baumann wrote:
> In lugnet.robotics, Justin Fisher wrote:
> > Hiyall. I just got my Lugnet posting access working again, so I thought I'd post
> > a here's-my-Lego-webpage link. Ignore as you see fit :-)
> >
> > One of my areas of interest is building solar-powered robots (and the necessary
> > custom mindstorms parts to make them work). I recently put up a page with some
> > pics of the solar rover I took to NWbrickCon, and some RCX geiger counter
> > sensors:
> >
> > http://home.earthlink.net/~stuff.tm/solarlego/nwbrickcon05/index.html
> >
> > Some various related stuff at the main page:
> > http://home.earthlink.net/~stuff.tm/solarlego/index.html
> >
> > Also at NWBrickCon, the tip of one of my models just barely enters the frame of
> > a photo of something else in Brick Journal issue 3. That's close to getting a
> > model in print, but no cigar. Maybe next year :-)
> >
> > - Justin
>
> Very, very impressive !!!
>
> As Philo, I also would like to see more details of your designs. There is one
> question that is tacking me:
>
> When we were working over our "Mars"-project, we tried to use the LEGO solar
> panels, but we could not extract more than 18mA from one panel under artificial
> light. How do you get those 500mA at 10V?
Thanks :) As to the power results, I'm not sure how familiar you are with solar
cells, so if the following isn't useful, ah well :).
The difference in energy you get from sunlight compared to artificial light is
massive. Running solar from artifical light gives really poor results, often
unuseable. So I use sunlight whenever possible. In order to get the display
working with artificial light I had 500W halogen lamps so close that I could
only run things for a few minutes at a time before the panel got hotter than I
was comfortable with, and even then the robot got much less energy than from the
sun. But at least it worked :) So, first point, that 500mA figure assumes
sunlight.
Solar panel voltage is determined by how many cells are in series, and the
current produced is determined by the surface area of each cell. So the second
point is simply that the custom mindstorms solar panel uses bigger cells and
more of them than the Lego solar panels.
Third point, the 500mA is best-case rating for the cell, (measured at short
circuit), meaning you won't really see anything like it normally. Normally the
panel is not exactly facing the sun, the sun is not at high noon, the cells are
soon heated by the sun (reducing their efficiency) and the transparent plastic
under which the cells are mounted will reflect some of the sunlight before it
reaches the cells. With these (and other) things in consideration, I'd consider
100mA at 10V during real-world use to be doing fairly well. You're just not
going to get that 500mA any practical way. (Though having the robot aim it's
panels to track the sun helps). However 100mA is enough for constant activity if
the motors are geared down to reduce load on them. And with the sleep-resume
modification, even that 18mA would be enough to get short periods of activity,
assuming it was 18mA at 8.5V or higher.
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Message is in Reply To:
 | | Re: MOC: Working solar powered rover and geiger counter
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| (...) Very, very impressive !!! As Philo, I also would like to see more details of your designs. There is one question that is tacking me: When we were working over our "Mars"-project, we tried to use the LEGO solar panels, but we could not extract (...) (19 years ago, 7-Feb-06, to lugnet.robotics)
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