Potato Battery Driven LED

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Introduction: Potato Battery Driven LED

So, if you looked at my profile you would see that I like physics.  When the challenge for “Potatoes” I just knew that I need to do a project that highlighted the lowly “Potato Battery”.  So here is how to make a Potato Battery and have it light an LED light.

Step 1:

Supplies:
Potatoes
Galvanized nails
Shinny copper pennies
Wires with alligator clips on each end (2+ per battery)
LED bulb
Multi meter
Knife
Cutting board

Step 2:

A battery is a way to store electrical energy.  For a battery to work it needs to have 3 things, two electrodes (metals, one + and one -) and electrolytes (minerals).  The batteries we are going to make today uses the electrodes of copper (pennies, anodes, +) and zinc (galvanized nails, cathode, -) and the electrolyte of K (Potassium) that is found in potatoes.

Step 3:

Take a potato

Step 4:

and cut it in half. This will make 2 batteries. Potatoes are juicy, which is part of the reason they can be made into batteries.

Step 5:

Take a knife and put a slit in the potato and slip the penny into the slit. Push as much of the penny into the slit as possible, you want just a little bit sticking out of the potato. Push the nail most of the way into the potato,(at this point I cut the nails in half, so that they weren't so tall). Do not let the electrodes touch, keeping them about 1 inch apart.

Step 6:

Turn on the Multimeter and put it at the lowest voltage reading. Make sure the red probe is in the + slot and the black probe is in the – slot.

Step 7:

Use the red line to touch the penny in the potato and the black line to touch the nail. You can read how much voltage you have available in this potato battery. It reads .85 volts, not bad but not enough to do anything fun.

Step 8:

To increase the voltage, you will need to create more potato batteries and wire them in a series (that means to connect the + electrode of one battery to the – electrode of the next battery). So I created 3 more batteries from 3 more potato halves.

Step 9:

Then I used the alligator clips connected to wires and wired first 2 potatoes together,

Step 10:

this time the voltage read 1.69 volts.

Step 11:

Let's take a minute and look at the LED light. It has one long leg and one shorter leg. The longer leg is the anode (+) and the shorter leg is the cathode (-). I clipped the batteries to the LED light (+ to+ and - to-), no light, therefore, not enough voltage.

Step 12:

I wired all four batteries together in series, and found what the total voltage is of the 4 batteries was 2.38 volts and I again wired in the LED light, again no light.

Step 13:

Finally I wired six batteries in series and it had a 4.05volt reading.

Step 14:

This time the light lit up!  Hurray!   Potatoes can be used as batteries.

Step 15:

Have fun playing with your new batteries, maybe you would like to experiment with increasing current by wiring the potato batteries in parallel as well as series.  Good luck and Enjoy!

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    2 Tips

    Use Red LED. It lights up at lower voltage. Took me 3 volts to get a blink of red

    You can also use the covering of AA battery for zinc if unable to get galvanized nails. It's the layer under steel cover

    Questions

    I created a potato battery in series with my daughter it read 4.9 v we used a lamp from one of her circuit boards that says 3 Volts 0.2amps and tried to connect it.. it doesn't light.
    I tried it multiple times and can't get it to light. We put it on her circuit board with a battery and it works and then we try our potato battery series and it doesn't work. Any ideas?

    23 Comments

    I have made many experiments with potatoes, but there was no difference, when I measured the output for boiled potatoes and raw potatoes.

    When you make the experiments with led in different colors, you will find, that you need more power to lightening the green led.

    It is not only the voltage, who counts but also the current, and green led need more current than white.

    Thanks for the info and thanks for sharing.

    Boiling them definitely makes a difference (or just microwave them). You won't notice it if you just measure the voltage but they are able to output more power. This is because cooking them reduces the internal resistance.

    Cool. Sound like an experiment to me. Thanks for sharing.

    I'm doing this for my Science fair! Thanks for the idea!

    You can also make batteries out of lemons, might help you mix it up a little  .Which would be better, lemons as batteries or potatoes?  Good luck on your science fair project.

    How many of each do we need???

    Depends on how much electricity you want to create. You will need two pennies and two nails for each potato section. Since I have no idea what your are after I really don't know how many of each think you will need. Read the Instructable and do the math, and yes I did some algebra to get the answers I needed to write this Instructable. Good Luck!