Instructables
Picture of How to Make Batteries From Spare Change
 
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Step 1: See The Video!

What's a penny worth these days?  Not much, but could there be some free energy hidden inside your spare pennies? You'd be surprised! Watch the video to learn how you can put together stacks of pennies to form makeshift batteries that can drive small-current devices like LEDs and calculators.

Step 2: What Kind of Pennies?

Picture of What Kind of Pennies?
US pennies that are newer than 1982 will work for both of these experiments, because they're nearly 98% zinc.

For more information on US pennies, including what date ranges contained what ratios of copper and zinc, click here!

Step 3: Power a Calculator With 3 Pennies!

Picture of Power a Calculator With 3 Pennies!
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Here's a fun experiment!

Pick up a calculator from the dollar store and remove the screws on the back so you can get to the battery. Remove it, and save it for another project.  

Now pull the negative and positive leads out of the casing and attach wires to the terminals if you can.  I just twisted the wires to the battery leads, and used electrical tape to hold them together.

Now it's time to make the penny battery.

I found the easiest way to make one is to combine the pennies with some zinc washers from the hardware store.  A pack of 30 is about $1.

Get some cardboard, and cut circular pieces so that the edges are just bigger than the pennies.  Let them soak in white vinegar for about 1 - 2 minutes.

Note: Any kind of vinegar should work, and if you don't have vinegar, try salt water, or lemon juice.  They will all work just fine.

Start your battery cell by placing a piece of aluminum foil on your workspace, and place 1 zinc washer at the end.  Next, take a piece of cardboard, soaked in vinegar, blot dry it on some paper towel, and place it on top of the washer.  Lastly, place the copper penny on top of the cardboard, and the battery is done!

An individual battery cell is a zinc bottom, copper top, and separated by a material like paper or cardboard that's been soaked in an electrolyte. 

From my testing, each cell yields just over 0.6 volts, and around 700mA.  The copper top is positive, and the zinc bottom is negative.  This calculator needs around 1.5 volts, so I used 3 pennies, 3 washers, and 3 pieces of cardboard soaked in white vinegar.  (3 cells x 0.6 volts = 1.8 volts approximately)

I added wires to the top and bottom for ease of use, then used some electrical tape to hold it together.  The aluminum foil is no longer needed.  

This type of battery cell is pretty much the same as the first one ever invented by Alessandro Volta in the early 1800's, which came to be known as the "voltaic pile".


Step 4: It Works!

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The wires can now be connected to the correct battery leads that were pulled out earlier, and when you press the "on" button the calculator will fire right up!

I tested out a few functions and everything calculated correctly.

It's amazing to think you can run low current electrical devices on this penny power hack!  It works great, and as long as the cardboard is moist with electrolyte, it should work.  

If your battery stops working, try re-soaking the cardboard in a little more vinegar to get it wet, then try again.  It should fire right back up!  

Step 5: Making a Larger Wet-Cell Battery

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Here's another way to make the battery if you don't have access to zinc washers;

Pick out 10 pennies newer than 1982, and use 100-grit sandpaper to sand one face of the penny.  The entire inside of the penny is zinc, so sand the face until the whole surface exposes the zinc. 

Once again, cardboard needs to be cut and soaked in an electrolyte like vinegar, salt water, or lemon juice.  In this case, I didn't round the edges.  You can see the sharp corners, and that's ok as long as they don't touch.  If the cardboard pieces touch, that section of the battery will short out and decrease the performance of the unit as a whole.  

You can build your battery cells the same way you did with the washers, as long as the pennies are all facing the same direction.  With this method, the zinc top is the positive, and the copper bottom is negative.  

By connecting 10 cells in series (stacking them on top of each other), the electrical potential will jump to nearly 6 volts!  This should be more than enough voltage to drive an LED… or TWO?!?

You can get an LED to light up by pressing the long lead of the LED (positive) on the top, and the short lead of the LED (negative) on the aluminum foil base.  

LEGALITIES: Some people have asked about the legality of treating pennies in this manner.  The federal law states that there are exceptions made for use as "educational, amusement, novelty, jewelry, and similar purposes as long as the volumes treated and the nature of the treatment make it clear that such treatment is not intended as a means by which to profit solely from the value of the metal content of the coins." For more information, click here!

Step 6: How Long does an LED Stay On?

Picture of How Long does an LED Stay On?
With the stack of 10 pennies, I attached a green LED and wrapped it all up with electrical tape in hopes to make it air-tight.  

I set it on my shelf and watched it for a few hours to see when it would die out.

I was amazed that the light actually stayed lit for over 16 days!!  I really am impressed at how well that worked out!  

Well, there's an energy idea that's worth a few cents.

Haven't see the video yet? You can still see it here!

If you like this project perhaps you'll like some of my others. Check them out at www.thekingofrandom.com
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dudes5 months ago
What kind of led is that? My LEDs won't light up brightly at all. Help.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
dudes theqwertman5 months ago
Actually I think he said 20 microamps or .02 MA. So more like .07 Amp-hours. So charging a smartphone... Maybe not.
Really? It's hard to believe. I'll have to give it a try sometime. :)
man u r so cool I love your you tube page
Fixitmyway8 months ago
Just a thought here, but if you were to drill some small holes in the pennies. Would that possibly increase your voltage or amps given the extra surface area in the zinc to react? Just a thought... Love your projects!
pokemech8 months ago
This would be a neat party trick.

you should be able to find pennies and cardboard almost anywhere, the LED might be the problem...
amazing
tealk1 year ago
i just made this battery. i used washer (i think they are zinc) used 75% copper 25% zinc coin ( its Serbian 1 rsd coin same as 2 cents in america )
it show from 4 coins,4 washers, 4 cardboard pieces, i got 3,9 V
i will make throwie with small red LED and i will follow how long can it last
tealk tealk1 year ago
because coins are copper my improvised battery last only 4-5 hours,.... tommorow i will try with only washers. and one with only coins
great instructable!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
theargha1 year ago
Is the led still lighted?
Bill WW1 year ago
Great and educational project - saw the YouTube version. I am always happy to see that kids get involved with learning about science (comment below).

Sheet copper is available commercially, so you don't have to use pennies. My friend is a sheet metal worker, he gave me scraps of .025" pure copper sheet.
wolfgang641 year ago
I did this with my eleven year old daughter last sunday and let her take it into school on Monday, after one freaked out phone call from the principals office and a lot little explanation (we live very close to Newtown CT) it was a smash hit her science class. Thank you. The only Problem is the science teacher wants to know what other tricks I have up my sleeve. P.S. I did give you full credit.
The King of Random (author)  wolfgang641 year ago
That's an awesome story! I love it, and thanks for the credit :D

Congratulations on your success with it!!
looks like you know your chemistry
I can do a few things but am always interested in learning more.
enojo.jon1 year ago
I would have loved to do this, its just too bad they have gotten rid of the penny in Canada...
The King of Random (author)  enojo.jon1 year ago
Yeah bummer. do you have anything else that's copper? It will work the same. Maybe some copper wire?
Hmff1 year ago
how many cells would you need to power a convenrtiona light bulb?
The King of Random (author)  Hmff1 year ago
You mean like a 100 watt lightbulb? Way too many to be practical in the least.
indigo4011 year ago
anything containing zinc will work which happens to be the main active ingredient in deodorant, So the story goes,
One day after updating my battery banks I put some deodorant on & by chance looked at the label seeing it contained zinc so I gave it a shot & it worked since then I've found hundreds of combinations.
The King of Random (author)  indigo4011 year ago
Very awesome! Your instructable deserves more views!
indigo4011 year ago
http://www.instructables.com/id/Speed-Stick-Power/

I made my first instructable based on the deodorant penny battery I made
The King of Random (author)  indigo4011 year ago
You are awesome :) Where did you get the idea for using deodorant? That is such a great idea!
indigo4011 year ago
it is rechargeable i tried with a 4.5 solar cell and upgraded the amount of pennies and deodorant to match the 4.5v of the cell to avoid overcharging either a potentiometer or battery charge controller or even a resistor would work. I have been experimenting with different deodorants, zinc based ointments, among other things as well
evingoz was
The King of Random (author)  indigo4011 year ago
I love where you're going with this! Where did you get the idea?

I feel like I have a million things going on right now, but I want to try this sometime for myself. I know you went over the basics, but what would you say are the basic step by step? I'm not familiar with vinegar paper.
indigo4011 year ago
This works for sure, if you want to add the cool factor use speed stick deodorant, pennies, vinegar paper, and tin foil. it takes about 10 pennies per led and works for 3 months running on the 1st

(i believe any deodorant with zinc anything will work. The solid white kind works best in a clump on a penny. Nickels work too, 6 per volt
The King of Random (author)  indigo4011 year ago
Interesting idea! With the suspended zinc particles, do you suppose the battery could be re-chargable?
TaffGoch1 year ago
I'm assuming that the pennies must be copper pennies, which are no longer minted.

If a penny has a date before 1982, it is made of 95% copper. If the date is 1983 or later, it is made of 97.5% zinc and plated with a thin copper coating.

Is the copper-coated penny sufficient, or must the penny be pre-1983 copper?
The King of Random (author)  TaffGoch1 year ago
I think any penny will work. These were of the 2.5% copper variety (copper plated only).
This could make a very nice science project for high-school-ers :)
I agree! :D
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
At 20mA (estimate green LED usage), that means your battery has over 7 Amp-hours! That could charge up a smartphone several times.
mikenaly1 year ago
Have to ask. You blot the cardboard to remove excess moisture. What is the reason for this, and would submerging the cells in the vinegar short them out, or allow for a greater amount of electrolyte to power the battery?
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