questionsanyone have any idea how to make a potato clock…


I know that you want as much distance between your galvanized nail and the copper wire. You want to maximize the amount of potato between the two poles.

I have never done this but electricity tells us that the least amount of resistance is key. I would imagine a smaller nail and lower gauge wire would be ideal. Also, be sure your connections to the clock are solid. Perhaps solder the connections.

Now you've got me interested in this.

EDIT: Perhaps a larger potato would be beneficial. I'm thinking giant baking potatoes. Should be able to pick up some at your local grocer.

Also, would a series circuit or a parallel circuit be more beneficial?


Also, you can only use 2 potatoes... but what if you used 2 very large potatoes and cut them in half? Could you then have 4 potatoes made from the 2? Sorry, loopholes has always been a mindset for me


Boiling your potatoes first appears to make for more efficient energy transfer. Boiling in heavily salted water is probably best, but that is just my guess, the article doesn't state one way or the other and I have not experimented.

Looking at the pictures it appears to me to be equal sized chunks of potato sandwhiched between a copper plate and a zinc plate, then connected in parallel. I may be wrong it is hard to track the jumble of wires.


How do you make a potato clock last? Make everything else first! :)


@capguncowboy: Batteries connected in series increase voltage and connected in parallel increase capacity. However, connecting non identical batteries in parallel can cause unequal drain and voltage drops.

A single potato has enough voltage, so serial is unnecessary. Parallel could (theoretically) work as long as the potatoes are the same type, age, and size.


I'd go with @daefaroth for boiling, but with clear gatorade.

Or whatever has more Zinc, I guess.


(To be honest, I have no idea what I'm doing.)


@jsimsace: :::standing up to applaud and whistle wildly:::


For what it's worth, I've never heard of boiling the potato, and in about a dozen google searches I found no mention of doing so. I would think that boiling it would result in a significantly shorter life span for the potato's usefulness.


Most interesting and fun question I've seen on here in a while.

I have nothing helpful to offer. Just that it made my morning happy to have one of the first things I read was a suggestion to boil a potato in Gatorade. :)


So far cutting and boiling it seem like a bad idea, unless some proof states otherwise. I have seen read this thing could last up to 2 weeks. I would imagine the potato would start to loose integrity. I was thinking hairspray the potato to keep it from drying out.

I did some googling myself and did not find much so I thought I would ask here.

Are you sure I do not want big copper wires?


@caffeine_dude: This is a question born of curiosity, not from knowledge: When I was a kid sweet-potato jars were a popular way to make a sturdy, green viney plant for the house. Stick small nails or toothpicks around the "waist" of a sweet potato and set it into a wide-mouth glass jar so the nails rest on the rim of the jar; the potato should be half in and half out of the jar. Fill the jar with enough water to cover the bottom inch or two of the potato and set the jar on a sunny windowsill. In a few days it will have roots in the water and a viney growth on top. These things used to last for many months and grow to several feet if not trimmed back.

That said, why wouldn't the potato in your experiment last as long?


In a commercial cell, the area of the electrodes is maximized, to get the most possible area for the chemical reaction.

If you just stick two nails into the potato, the chemicals responsible for the "battery" effect will eventually become depleted in the region close to the nails, causing the cell's internal resistance to increase, and the output current to decrease.

So the "ideal" potato cell would use something with a large surface area... such as window screening , foil, or flat plate electrodes. Of course the two electrodes are different metals. Make a good electrical connection to the electrodes... solder if possible.

Slice the potato so it's flat on two surfaces, and sandwich it between the electrodes. Place some sort of weight on top, to maintain pressure between the electrodes and potato. And finally, the exposed surfaces need to be sealed so the moisture doesn't evaporate, because the potato-electrode junction needs to remain wet.


@capguncowboy: Actually, to miminize resistance, you want larger gauge wire. But a digital clock uses very little current, so probably 20-gauge wire is more than adequate for this project.

And you want to maximize surface area between the electrode and potato, so you want a larger diameter nail. (But as I said above, screen or a metal plate, in good contact with the potato, will give much more surface area than any nail.)


@crowbite: Cool because I used a meter on it and found if I used a.... 18-20 gauge speaker wire and spread the threads out I received more amps and volts. I wonder if it would be cheating to use 2 nails.

If I spread it out (the copper), do I have the chance of using the energy too fast?

I do not think I could hammer the nail because the nail is coated. What do you think?



Yes, spreading out the wire strands is a good idea. Seems to me it might be difficult to keep them spread out when you assemble the final product. That's why I suggest copper window screen, with your "output" wire soldered to it for good contact.

The other electrode, galvanized nail... I'm trying to think of some sort of screen made of galvanized steel, with a big surface area. Maybe a local sheet metal shop can give you a potato-size piece of galvanized steel... then the potato will have to be very flat to make good contact. Again, solder (or screw-terminal) the "output" wire to the steel.

Don't worry about using the energy too fast. The current will be limited by the internal circuit of the clock movement... it will use only as much as it needs. If you maximize the available energy, then your battery will last longer before it's depleted.

And yes, wrap the potato in Saran Wrap to keep it wet, then put a brick on top to maintain good contact pressure.