Building a "Robinson Crusoe" Battery

[JoeSP]

I've been wondering that too. I'd likely pick salt water electrolyte
and carbon and steel electrodes. Assuming there is no ready metal on
the island, hopefully there would be a zip on some clothing, a button
or something. Burnt vegetation could provide the carbon.

I found a little 1" or so bottletop sized cell gave in the region of
half an amp at 1v. The electrodes corrode quickly, in a day.

What's the point? You can make a battery out of many, many substances, but
only a few of them are economical, practical or useful.

 

[clifto]

Robinson 'could'--with nothing more than the battery and some
wire--transmit radio signals in Morse....

Yeah, but all the people who understand Morse would be too old to be
traveling around deserted islands.

 

[JoeSP]

We had a dozen citrus trees in the back yard till recently (citrus
canker eradication program... the state cut em all down). I wondered
about building 'citric acid' electrolye batteries as I picked up
garbage cans full of oranges and grapfruit.

Much cheaper sources of better electrolytes exist. Using free scraps and
substances will produce a theoretical battery much sooner than a practical
one.
I sense that this discussion is being propelled by the desire to get
something for nothing or very cheap. If you do your homework, you may be
able to match the materials available to the desired output, and get
something safe and practical, but I doubt it. I'd be as interested as
anyone to see the results if you're successful.

 

[JoeSP]

Good question....in the original posting I mention communications
equipment.

It is assuming that Robinson Crusoe wants to be rescued.

The discussion has demonstrated to me how we tend to underestimate how
hard it is to provide basic needs to support our technology based life.

Maybe we should enlarge the scope of the problem and allow active power
generation.

Any ideas as to how to generate power?

TMT

Why do you think it was mostly dry cells and dynamos a century ago? Don't
you think they experimented with every metal and electrolyte available
before coming up with the lead-acid battery and the dry cell? If you're
keen to repeat history, have fun.

 

[JoeSP]

"Robinson 'could'--with nothing more than the battery and some
wire--transmit radio signals in Morse....
No accounting for range, of course.
jak "

True...but this just shows how important the battery really is...and
that is why I chose to make it the main focus of Crusoe's efforts to
get attention.

If the professor couldn't build a crude radio transmitter with all the other
advanced technology he managed to build, he wasn't a very good professor.

 

[JoeSP]

Well the history channel just showed a 2000 year old battery
found in Bhagdad. It had an iron rod negative pole and a copper
cylinder positive pole, and probably used vinegar as the electrolyte.
A clay jar housed the unit. What would a battery be used for 2000
years ago? BION, electroplating gold!

It was probably used by Hammurabi to play jokes on his friends by
electrifying the chairs.

 

[John Savage]

in an emergency, For materials, I would use a brick to smash Radio
Shack's window and get all the batteries I need.

All the batteries? Then you'd better do that before Friday!

To fabricate a cell with dissimilar metals + salt water electrolyte you
simply search in the sand for different bags of dubloons--and hope they
came from batches of alloy sufficiently dissimilar to generate a worth-
while potential difference. If not, then jump the next pirate who comes
ashore and steal his sword: it's iron or steel. Use that as one of the
electrode metals for your battery. But you can't escape the island in
the pirate's rowboat, that would be against the spirit of adventure ....

 

[John Savage]

simply search in the sand for different bags of dubloons--and hope they
came from batches of alloy sufficiently dissimilar to generate a worth-
while potential difference. If not, then jump the next pirate who comes
ashore and steal his sword: it's iron or steel.

^^^^^

Ahh, me Hearties! I misspelled 'cutlass'

 

[John Savage]

simply search in the sand for different bags of dubloons--and hope they
came from batches of alloy sufficiently dissimilar to generate a worth-
while potential difference. If not, then jump the next pirate who comes
ashore and steal his sword: it's iron or steel.

^^^^^

Ahh, me Hearties! I misspelled 'cutlass'

 

[John Savage]

simply search in the sand for different bags of dubloons--and hope they
came from batches of alloy sufficiently dissimilar to generate a worth-
while potential difference. If not, then jump the next pirate who comes
ashore and steal his sword: it's iron or steel.

^^^^^

Ahh, me Hearties! I misspelled 'cutlass'