Pumpkin Battery_24.jpg
Here is a fun food hack I did over the weekend that is a useful alternative to lighting jack o' lanterns with candles or traditional batteries on Halloween. It could also double as a center piece for the fall and is easily made with common household items.

You'll need miniature pumpkins (I used Baby Boo), unflavored gelatin, salt, vinegar and oil from the grocery store. You'll also need 18 gauge copper and aluminum wire, an LED (preferably one that runs on 1.5 volts- I used one that I had candied in an earlier project), wire cutters, pliers, a ruler and multimeter. In the kitchen you'll need a medium sized bowl, small bowl, small pot, cookie sheet, pairing knife and mellon baller (or spoon). If you already have the tools and kitchen stuff the project should cost about $20.

Update: One week later and the pumpkin battery is still generating 1.5 volts! My follow up post on it is here.
 
Remove these adsRemove these ads by Signing Up

Step 1: Cut and Gore the Pumpkins

Pumpkin Battery_1.jpg
Pumpkin Battery_2.jpg
Start by cutting the top off a pumpkin in a circle and scooping out the seeds and innards. You will only need seven pumpkins, six to make the battery and one to house the light so choose the battery pumpkins to be slightly flatter and the center pumpkin to be slightly larger so you can cut a decent face into it. Keep the guts and seeds for later!
susanchen2011 says: Jul 11, 2012. 8:31 PM
I like this!!! Great idea!!!
flodato says: Oct 25, 2011. 6:02 AM
I started this project last night, but chickened out on the electrolyte because it looked completely different than yours. Tried just salt water and generated 2.5 volts with 6 pots. For some reason my light would not illuminate. I used 22 gauge aluminum wire and 20 gauge copper. I doubled up the thickness of each wire by using 16 inches of aluminum, folding the wire in half, and twisting it together with my cordless drill. So now I have nice, thick 8 inch copper and aluminum wires.

The light, I sanded the aluminum that I used because it was blue. I thought the color would be a nice contrast to teach the kids about what I was doing. However, after roughing up the surface the light still did not illuminate. I got the LED off of some Christmas lights... not sure what the voltage/amps of it is, but it worked with my cell phone battery. I will keep you posted. Please provide some pointers if you have any! Thanks - Frank
abeaupre says: Oct 31, 2011. 2:51 PM
LED- Light Emitting Diode. Diode. Diode. (I repeat diode because sometimes I forget...and I work with stuff like this frequently.). Diode.

A diode only allows current flow in one direction- check to make sure you have the wires on the correct lead. IIRC, the longer of the two is the positive.
Also, thin gauge wire like that is usually covered with a kind of varnish for insulation- you'll have to burn it off for that wire you twisted together to actually be one stranded wire. What you probably have now is just one really long wire that's wrapped around itself a bunch. Good luck! If it weren't already 6 in the evening, I'd try this one. Definitely keeping it in mind for next year, and I'm going to incorporate a huge Frankenstein switch and glam it up to look all mad scientist-y.
emdaniels (author) says: Oct 25, 2011. 10:38 AM
Ok- what is the blue coating on the aluminum? Did you sand down the coating where the aluminum is immersed in the electrolyte and where it is wrapped around the copper wire? The LED I used generated a lot of lumens for low voltage- it typically runs on 1.5 V. LED voltage requirements span 1.5 to 3.7 or so, depending on the chemical composition. Radioshack would probably carry a wider selection, or you could order them, but your best bet would be to look for red LEDs as they tend to require less energy to light. Definitely keep me posted!
flodato says: Oct 25, 2011. 12:22 PM
The aluminum wire was offfered in blue, yellow, red, etc. colors. I will try adding orange juice or vinegar to the solution to see what happens. I purchased 2 1.8V, 20mA LEDs at Radio Shack. I don't think that is the problem though. I think it's the connection and the solution that I made. Gonna mess with it tonight. Thanks! Having a blast with this.
Kasm279 says: Oct 20, 2011. 9:34 AM
I cannot put into words how epic this project is.
emdaniels (author) says: Oct 20, 2011. 11:34 AM
Thanks! I hope you have fun making it.
shakespeare1212 says: Oct 20, 2011. 10:39 AM
Really,really neat. But isn't it possible that the punkins themselves could act as an electrolite? Like a potato battery? Did you try that?
TJSonOfAnder says: Oct 20, 2011. 11:20 AM
I had the same thought when I first saw this... But I'm not sure how you would do it. It doesn't seem like plugging wires into the meat of the pumpkins would generate enough energy.
emdaniels (author) says: Oct 20, 2011. 11:30 AM
What would probably work is a salt water solution poured into the pumpkins (with guts and seeds in place) around the wires. I'd be willing to bet it would give off roughly the same energy (1.5 volts) as my experiment, but then you'd be wasting the seeds you could be eating! :)
tromano says: Oct 18, 2011. 4:11 PM
Great project... make yourself a "Jewel Theif" and you will get longer brighter runtime out of the pumpkins or even use less of them... check it out
oanderson says: Oct 20, 2011. 7:22 AM
Great idea!
emdaniels (author) says: Oct 18, 2011. 5:24 PM
Good idea- for those interested I found this link on instructables: http://www.instructables.com/id/Make-a-Joule-Thief/
randofo says: Oct 17, 2011. 12:13 PM
This is entirely awesome. You should enter this into The Mad Science Fair contest!
emdaniels (author) says: Oct 17, 2011. 1:14 PM
Thanks! Good idea- I think I'll do that. :)
Penolopy Bulnick says: Oct 17, 2011. 9:51 AM
This is really cute. And the metal you use to connect them gives it a real Frankenstein-likeness to it :)
emdaniels (author) says: Oct 17, 2011. 10:23 AM
Thanks Penolopy!
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!