I would just use one potato, at least for starters. If you want to get
much current out of one of these batteries, you need to use lots of
copper wire or sheet inserted in the potato, as well as lots of
zinc-coated nails. There's not much point in using more potatos until
you've used so much copper and zinc that the potato is starting to get
crowded.
One of the main problems with potato batteries is their resistance
to electrical flow. You can make many potato batteries and hook them up
in series to make a combination battery with more voltage (the voltages
add), but also more resistance (the resistances add too). You can hook
the batteries up in parallel to get more current out of the combination
battery at the same voltage as one battery, overcoming the resistance
problem slowly, at the expense of more copper, zinc, (and space on your
potato). It depends on what you want out of your battery!
If you want to hook up your batteries in parallel, then you can
use the same potato and put all the copper nails on one side and all
zinc ones on the other, and electrically connect all the copper
together into one terminal of the battery, and connect all the zinc
together to make the other terminal. If you want to hook them up in
series, then I'd recommend using separate potatoes for each stage,
because the electrical current might take a "shortcut" through the
potato if you had just one.
Mike W. (and Tom)
(published on 10/22/2007)
