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Why can't I get my voltaic pile (penny battery) to work?

I've been attempting to make a battery using the various instructables (https://www.instructables.com/id/Penny-and-Nickel-Battery/), but I can't get anything to register on the multimeter. I purchased sheet aluminum from the hardware store, and that doesn't work. I even purchased CuSO4, to see if that would help, but it still doesn't work! I follow the directions exactly, is there something else that I've been missing?

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I think the aluminum is your problem. It may have a greater electropotential difference than nickel, but the aluminum you are using has an atomic layer of aluminum oxide on the surface of it. The oxide layer may be creating resistance in your pile to prevent it from working. Also you have to look at the reaction equation to see if it will work. In an electrochemical reaction like this, one species has to be oxidized and the other has to be reduced. Not sure which way the reaction would go but if the Al needs to be oxidized then the aluminum oxide layer has already been oxidized and is stable, if the Al needs to be reduced, the Aluminum Oxide layer may be to stable to be reduced to Aluminum and Oxygen gas.
wordsworth (author)  alchemistdagger8 years ago
I sanded the aluminum and was able to get it to work. Thank you for your help!
wordsworth (author)  alchemistdagger8 years ago
Ok. I will try sanding off the aluminum oxide, and I'll see if that works. If it is the aluminum, then why couldn't I get it to work with the nickels?
Dr.Bill7 years ago
The pennies may actually be copper coated zinc. Try real copper cut from roof flashing or use wheat pennies. They are real copper.
kosimov7 years ago
The comments about the oxide layer on the aluminum are right on. In fact, that oxide is the thing which makes aluminum so desirable in practical applications; it forms so quickly and so uniformly that it prevents the aluminum from "corroding" when in the presence of, for example, salt solutions, so it makes aluminum cookware and all sorts of other items better suited than steel or other metals for common applications. The shiny aluminum which is present before it is exposed to oxygen turns a "grey" color in a flash, preventing the aluminum underneath from also reacting with the oxygen. Anything which can remove or penetrate this oxide layer will expose the aluminum so it can react in the battery, but that can be difficult; I suspect that the gain in potential obtained by using aluminum may be offset by the hassles of keeping it from oxidizing from experiment to experiment. Unless you do something fairly complicated to keep the surface from oxidizing (ie, "shiny"), such as encapsulate the whole thing in a non-porous non-permeable layer of plastics or glass or ???, it is going to oxidize over a period of time anyway, as oxygen tends to be "smart" and "cunning" and will find a way to get at the copper. Or, it won't. (heh heh heh heh.....) I guess this is one of those things you try a few ideas on; if an idea works well enough for you, all the theories were merely an exercise to keep up my WPM on the keyboard! In fact, I've made a living by violating (breaking) all these kinds of rules, by being too dumb to know my ideas won't work, so I go ahead and figure out how to make them work before some guy like me comes along and tries to tell me it won't work! So, good luck, and may the forks be with you. Seriously, I'd be interested in your results, for example, did you find a way to keep the aluminum from oxidizing long enough to be able to use the battery for something useful or fun? If so, how did you do it? Hint: way back in the olden days, like maybe, the sixties, cars used trim pieces made of aluminum covered with a tough layer of clear plastic that was fairly thick compared to the aluminum. It was attractive, flexible and tough, especially resistant to scratches, etc., within the limits of the plastics. Once they were broken down by UV in sunlight and other weathering factors, though, the aluminum AND the plastics oxidized and they quickly became unattractive. Perhaps there is a way for you to duplicate the technique; with today's plastics it may work much better than it did then (well, it often lasted 10 to 15 years or more, so I guess "that ain't bad"!). As I recently discovered when I attempted to use some newer pennies for another project, the newer pennies don't have much copper in them. They seem to be made of zinc? nickel? (or ???), with a thin layer of copper on them. I suppose if there was a way to get acid between the zinc? and copper, you could use one penny as a cell by removing the copper on one side, putting acid between the zinc? and the copper on the other side, then attaching wires to each side. Can't think of a way to do that, offhand, though, so we'll just use this method I suppose! Finally, I am going to try this for some other applications. It is quite entertaining, to me at least, to see that this can work. My older grandkids love to "play science", as they put it, and this seems like something they would really love to try. Thanks to all who came up with this! It really impresses me what I can find on the internet by way of creative projects to do all sorts of things like this. When I was growing up, all I had was encyclopedias, "Book of Knowledge", some scout projects, and some really ancient books in the library showing how to make toys out of buttons and string! Wow, I would have been in hog heaven with stuff like this! Larry
jtobako8 years ago
What is the aluminum supposed to be for?
wordsworth (author)  jtobako8 years ago
The aluminum was to replace the nickels. There's a larger potential difference between copper and aluminum vs copper and nickels (especially since nickels are predominantly made of copper).
Aluminum oxide will form almost instantly in air and underwater, blocking the chemistry you are looking for. Try to find zinc, maybe something galvanized or cut from some printing plates or the inside of newer pennies.
wordsworth (author)  jtobako8 years ago
I sanded the aluminum and was able to get it to work. Thank you for your help!