In the spirit of Halloween, I thought I would expand on the idea of fruit and vegetable batteries and make a battery out of pumpkins! This is a very quick and easy Instructable, so let's get started.
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Signing UpStep 1: Materials
Note: This can be done with just one pumpkin. The more pumpkins you use though, the more power you get! That being said, I used two pumpkins connected in series to get more voltage.
Here is a list of everything you will need to make this battery.
- Pumpkins
- Galvanized screws or nails
- Galvanized just means it has been coated with zinc, any thing zinc-coated should work.
- Something copper, like nails or segments of wire
- Wires
I got two galvanized screws and 2 pieces of a thick copper wire at the hardware store for less than a dollar. Any other zinc and copper items should work.
If you have alligator clips, that will make connecting everything together easier. These can be purchased in packages of 4-6 for a few dollars.
Step 2: Place the Galvanized Material
Put one galvanized screw (or whatever other item you are using) in each pumpkin. Leave a little bit of the screws sticking out to connect to the wires later on.
Step 3: Place the Copper
Put a piece of your copper material in each pumpkin as well. Place the copper near the galvanized material but make sure they are not touching inside or outside of the pumpkin.
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try boiling the pumpkin and then mashing it between zinc and copper plates in a series. works for potato by rupturing the cells and allowing electrolytes to flow more freely, thereby lowering the vegetable's internal resistance.
How much current do you get from this?
Will it run a joule thief?
The current is dependent on ohms law, Voltage = current*resistance
or Current = Voltage / resistance in this case. Increasing the surface area of
the Cathode and anode will indeed aid in the reaction processes and thus
increase the induced voltage, though possible only slightly. You should
consider using different Cathodes and anodes that might be more receptive to
Electron transfer. Increasing the size of the pumpkin would really only help
limit the Acids from becoming too diluted with ions and slowing the reaction.
This wouldn’t likely be an issue unless you were using a very small pumpkin. To
lengthen the life of your pumpkin battery, you would want to keep your pumpkin fresh and use a larger ratio of Cathode/anode material to a smaller surface area. To increase the voltage you could also try using a different Fruit with Stronger acids. From my understanding Lemons are an excellent source of power for these kind of things.
Getting a substantial amount of current from this is tricky. With just the two pumpkins in series, I was not getting enough current to actually be able to measure it with my multimeter. This issue is related to the chemical reaction that takes place within the pumpkins that generates the electrical energy. (I could explain this in greater detail if you would like.) As I mentioned in my last step though, you can get more current by connecting more pumpkins in parallel. For something small with low power demands, like a joule thief, I think several pumpkins in parallel should do the trick. I have not tried this myself though.
What if, instead of more pumpkins, just use more zinc/copper combinations of nails in the same pumpkin? Maybe on the opposite side.
That should work as well. I'm not any type of chemistry expert, but I believe the rate of the chemical reaction would increase if the surface area of the components involved in the reaction increased. For example, using a bigger galvanized screw (or other zinc item) would provide more zinc to react with the pumpkin and ideally increase the voltage and current available.
I agree, that was my basic reasoning behind it too. I doubt that the small nails will be able to drain the energy from the entire pumpkin. More likely just the localized area they are stuck to. Moving them might refresh the effect, and adding more to the same pumpkin might too. It's worth a shot I'd say.
Point #1) pumpkins are actually a Fruit. Point #2) all Fruits have acids filled Electrolytes. Electrolytes allow electrons to flow from on point to another, like ions do in water. Note* deionized water will not conduct electricity. Its because of this exchange that a complete circuit can be made from the - Anode(copper) to the + Cathode (Zinc); or galvanized nail this case, inside the fruit. this can be done with any variety of Fruit. Typically the stronger the acids the higher the voltage out put possible.
I don't know of the exact chemical (I think it is some sort of acid). But this 'chemical' inside the pumpkins reacts with the zinc on the galvanized screw. This chemical reaction frees up electrons which is where we get the electricity from. This would not work in just water, but I have seen salt water solutions work in a similar way (since salt has electrolytes).
Great idea, thanks for sharing ..
Actually, I never thought about pumpkin batteries before this instructable. I will experiment on tomatoes.
This is very interesting sir!
If I had pumpkins growing instead of watermelons I would definitely do this!
Actually, watermelons might work too! I have seen this work with potatoes and apples before, so I think just about any fruit or vegetable will produce at least some voltage.
Man I want some spaghetti squash with some sauce on top.