Alt-BEAM Archive
Message #01655
To: Matt Procopation proc@home.com
From: Bob Shannon bshannon@tiac.net
Date: Sat, 20 Mar 1999 20:43:24 -0800
Subject: [alt-beam] Re: Resilience of solar cells?
Matt Procopation wrote:
>
> I just received my first set of goodies from Solarbotics today, and I
> figured before I
> start mucking about I'd find out what sort of punishment these panasonic
> cells can take.
The bare cells will crack easily, but I've found a cheap, light way to
make the cells very tough indeed.
I simply glue some very thin aluminum sheeting to the back of the cell,
with
notches for the electrical connections. With a thin coating of five
minute
epoxy applied to the back of the cell, I place the cell onto the sheet
and hold
it in place with a weight as the epoxy dries.
The metal sheet must extend around the edges of the cell by a few
millimeters to
protect the edges of the cell. The weight squeezes out just enough
epoxy to make
a smooth fillit around the glass solar cell so there are no sharp edges.
The laminated solar cell is now so strong you can use it as the chassis
of your
robot by gluing the capacitors and such directly to the backside of the
laminated solar cell. This makes a thin, rigid, unified slab. Its very
strong.
I call this uni-slab construction.
> Share some of your horror stories with me. Do they tend to
> crack/shatter/etc when dropped
> from table height? How scratched up do they have to be before you notice any
> change in performance?
I had a uni-slab photovore (Slab-o-vorus) that was attacked by a
housecat.
The poor 'vore was flipped up and over the 3 inch walls of the beam
park, where is fell nearly 3 feet onto a hardwood floor. It apparently
hit on one of the wheels, as a motor shaft was broken clean off on one
side.
Other than the snapped motor shaft, the robot was undammaged even though
it was batted around (about 8 feet from where it fell) by the cat.
There was no solar cell dammage at all. The metal sheet the cell is
laminated onto has a 'major ding' that clearly would have been a broken
cell however.
Had the bot been built directly onto the solar cell, it would have been
a total
loss. As it was, I was able to replace the motor in about 20 minutes.
> I have numerous cats in my house (Not quite as many as those cat-ladies you
> read about
> with houses full of 300 cats, but slowly gettin there. Well, just 4, but
> they seem like more) and I
> I'm curious as to whether I should include some manner of structural
> protection around the
> cells on my bots.
Yes, make then solid bricks, like Slab-o-vorus.
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