🚀 go-pugleaf

From a table of the Electromotive Series, the copper-aluminum couple should
give quite a bit more voltage than indicated.  Probably what is happening
is caused by the oxide coating found on all aluminum.  The acidity of the
lemon is possibly not high enough to dissolve this oxide layer.  Zinc would
be a good choice, iron would be relatively poor.  Zinc is easy to find
around the home.  Cut open any ordinary flashlight battery, i.e. carbon-zinc.
Throw away the carbon electrode, scrape out the manganese dioxide depolarizer,
and keep the zinc shell.  Sand it well before using in the lemon.  Also don't
eat the lemons after the experiment; the metallic taste could be poisonous!

BTW, my knowledge of this comes from information on corrosion protection.
Eastman Chemicals Division is not involved with Kodak's new battery business.
I do know for a fact that the new batteries are not based on lemon technology;
however, how do you explain the lemon's yellow color?  :-)

                                       Barry L. Ornitz
                                       Eastman Chemicals Division Research
                                       Kingsport, TN  37664

Standard disclaimers apply.