How to build your very own soda battery.
A nice thing about this experiment is how relatively inexpensive it is. Large quantities of materials can be purchased for not a lot more than just doing it for one person, making it great for a classroom experiment. Often contractors and hardware stores have bits and pieces laying around and will gladly give them to you for a school project. You can also substitute almost any copper or galvanized steel to use for the electrodes. A word of caution, if using sheet metal for your electrodes, the cut edges can be razor sharp - trust me, I know first hand how nasty one of these cuts can be.
what you need:
- 2 liter bottle of most any soda (colas work well for this)
- Clear plastic cups
- Copper plumbing pipe
- Tubing Cutter (optional)
- Galvanized, zinc coated steel rod
- Hack Saw (optional)
- Voltmeter (optional)
- Test leads with alligator clips
- LED (Light Emitting Diode) rated at 2-3 volts
2 liter bottle of most any soda (colas work well)
Any soda with phosphoric or citric acid will work (just look on the ingredients label). it doesn't need to be any particular brand, store brand will work fine. It's the acid in the soda is what makes it work as the electrolyte in the battery. Colas tend to be more acidic, so they generally make a better battery. Not that soda is healthy for you to begin with but, don't drink the soda after using it in the experiment!
Any soda with phosphoric or citric acid will work (just look on the ingredients label). it doesn't need to be any particular brand, store brand will work fine. It's the acid in the soda is what makes it work as the electrolyte in the battery. Colas tend to be more acidic, so they generally make a better battery. Not that soda is healthy for you to begin with but, don't drink the soda after using it in the experiment!
Clear Plastic Cups: Virtually any plastic cups meant for drinks will work fine, they don't even need to be clear, if you don't want to see through them. The dollar store usually has these and they're a bit cheaper. 12 ounce or 16 ounce cups work well. For a more robust solution, try using the thicker plastic take-out cups used for soups and liquids. The ones from our local Chinese restaurant work great.
Copper Pipe: Copper pipe is available at most hardware stores and "big box" home improvement stores. It is usually sold in lengths of a few feet, so you'll need to cut it. Cut the pipe so that about an inch or so is above the cup. Most home improvement stores will cut if for you if you ask. This pipe is usually made from an alloy that is over 99% pure copper and makes an excellent electrode for out project.
Tubing Cutter: For about $3.00 you can buy a tubing cutter like this one and cut the copper pipe yourself. This is also available at most hardware stores and "big box" home improvement stores. Make sure you get one that meant for copper tubing and not PVC or some other type of pipe.
Zinc Plated Steel Round Rod: This is available in the hardware section of most "big box" home improvement stores. It may be listed as galvanized or zinc plated. What we're interested in is the zinc plating. It was originally intended to help prevent corrosion of the steel, but in this case we're using the zinc for one of our electrodes. 1/4 inch diameter works well and you can still attach an alligator clip to it. You'll need a have someone at the store cut it or buy a hacksaw (or have some other way) to cut it to length. A word of caution - a small amount of lead is often used in the alloy used to galvanize metal. Normal handling it should not be any problem, just be sure to wash thoroughly after handling it.
Hacksaw: This is a pretty common tool. Either you or your neighbor probably has one. If you need to buy one, you can pick one up for less than $10.00 from just about any hardware store or big box retailer in the tool section. If you're using one you (or someone else) already owns, make sure the blade is in good condition. You'll need some way of securing the rod to cut it. A vice would be ideal, but any means of securely holding it so that it can be safely cut would work. A sharp blade and a few good strokes should cut through a 1/4 inch rod pretty easily. If you own a Dremel type of tool, a cut off disk would make quick work of it. Be sure to wear eye protection while cutting it.
Multimeter or Voltmeter (optional): A voltmeter (or multimeter on the voltage setting) is only needed if you want to measure the voltage of the battery. You can also use a multimeter to measure the current of a circuit connected to your homemade battery. For this project an expensive or accurate voltmeter is not required. If you buy one locally at your local electronics hobby store, or big box retailer, expect to pay around $20. I've seen cheaper versions online for as little as 5 dollars. I've actually purchased one for about 7 dollars and it worked fine for a few years. It wasn't very accurate, but it served it's purpose for hobby use.
Test leads with alligator clips: These are wires with spring loaded clips on each end that make them ideal for temporary connections. They are like jumper cables only a lot smaller. you use these to connect your battery to something, like a voltmeter or n LED. These can be purchased online or from your local electronics hobby store. Expect to pay somewhere around $10 - $15 for a set. If you are handy, you can buy a bunch of clips and wire separately and make a ton of your own.
LED (light Emitting Diode): These are perfect for this type of experiment because they consume very little current and only a couple of volts. Look for one with a rating of around 2-3 volts and around 20 mA current draw. You needn't be exact, just close. If you don't know what this means, don't worry too much about it - I'll explain everything in my next update. These can be purchased online or from your local electronics hobby store (like Radio Shack). I don't like to mention retailers by name, but in this case, there is not a ton of local options to buy things like an LED or alligator clips. If you're planning a lot of these experiments, these can be purchased in bulk online.