Intro: DIY AA Batteries!
Today we're going to learn how to easily make our own batteries from very inexpensive household materials.
An AA battery is a standard size cylindrical battery commonly used in portable electronic devices. The exact terminal voltage and capacity of an AA size battery depends on the cell chemistry but are usually rated at or near 1.5 volts.
An AA cell measures 49.2–50.5 mm in length, including the terminal and 13.5–14.5 mm in diameter.
AA batteries account for over 50% of general battery sales and the average price of a quality AA battery can range from $0.59 to as much as $1.42 or more.
Think this would be helpful in an emergency? Is this a viable and renewable source of energy? Would this be a good way to teach kids about science?
Step 1: What You'll Need
To get started, the materials you'll need include:
- (1) Strip of Corrugated Paper (Cardboard Box)
- (12) Copper Flat Washers [Size #10]
- (14-16) Zinc Flat Washers [Size #10]
- (1) Shrink Wrap Tubing [2.5"x1"]
- (4oz.) Distilled Water
- (1oz.) Vinegar
- (4 Tblspns) Table Salt (NaCl)
You will also need the following tools:
- Soldering Iron
- Mixing Bowl
- Digital Multimeter
- Sand Paper
- Needle Nose Pliers
- Lighter (or Heat Gun)
- An Old AA Battery (for reference)
Step 2: Prepare Copper & Zinc
The Copper and Zinc Flat Washers are going to serve as your anodes and cathodes for your battery separated by an electrolyte. This battery will be constructed of 11 cells in series to create a robust 1.5 volts.
The Copper and Zinc washers should be clean, free of debris and roughened with 100 grit sandpaper and wiped until brilliant and shiny.
Step 3: Cut Cardboard
Next, we'll be cutting our corrugated paper into 11 squares. These will serve as a tiny sponge to absorb and suspend the electrolyte between our copper and zinc anodes and cathodes.
When cutting the cardboard squares be sure they are precisely the size of the washers. If they are too large they will create a short; if they are too small they will not hold sufficient electrolyte.
When finished put them to the side.
Step 4: Prepare the Electrolyte
Voltage is a potential difference which we find with copper and zinc. The electrolyte is the medium through which this charge can pass.
To prepare the electrolyte, first stir the 4 Tablespoons of Table Salt into the 4oz. of Distilled Water until the water has reached it maximum salinity and the salt no longer dissolves. The water should have a milky white appearance. Be sure to mix thoroughly before adding vinegar.
Once settled, add 1 oz. of Vinegar, mix and allow to sit.
Step 5: Soak Paper
Once your electrolyte mix has been left to stand for approximately 5 minutes, you can insert your cardboard squares to let soak. Be sure to submerse all squares, stir and allow them to float until they are ready to use.
Step 6: Stretch Shrink Wrap
To ensure a tight fit we have selected a shrink wrap that is slightly smaller in diameter than our washers. We will need to stretch it temporarily in order to insert our washers and paper squares.
Insert the closed Needle Nose Pliers and open them slowly while working them around until stretched to 110% in diameter. Repeat on other side.
A washer should now fit snugly when placed in the tube horizontally.
Step 7: Test Components
As discussed, we will be building 11 cells consisting of Copper, Electrolyte and Zinc.
Before constructing our battery we will make one cell to test our components.
Simply stack one Copper Washer, one soaked Cardboard square and top it with one Zinc washer.
Next we will test it with our Digital Multimeter. The red wire should be in the Voltage slot, the black wire in the COM slot and the Multimeter should be set to at or near 20vDC. Then, contact the black lead to the Copper washer and the red lead to the Zinc making sure they are isolated and not touching each other or anything else.
You should now see a display of somewhere between 0.05 and 0.15 volts!
If your reading is higher than this, don't worry, the voltage may climb but will then reduce. If you're reading is lower than this check your components and try again. If your reading is zero, check your contacts and make sure your Multimeter is set correctly.
Step 8: Plan the Core Build
Before getting started, take a look at the image showing how the construction of the cells will make your battery.
Notice the order: Copper, Zinc, Electrolyte, Repeat.
Step 9: Build the Core
To build the core, we will be stacking the components making sure they are flat, without spaces and without compressing the electrolyte mixture out.
First insert a Copper Washer pushing it 1/4" from the end and making sure it is horizontally straight. Next, drop a Zinc Washer on top and then add one of your soaked electrolyte squares. It is helpful to have a pen or nail to push the cardboard down evenly, just be sure not to press too hard.
Then repeat, Copper, Zinc, Electrolyte, tap down, Copper, Zinc, Electrolyte, tap down... until the last zinc washer tops the stack.
Before sealing your battery, compare to a standard AA Battery to ensure the correct length. If necessary, add additional Zinc Washers until the correct length is reached. Note that the protruding nub on the positive side will be added later with solder.
Once the correct length is reached, begin heating the end that you started with, making sure to make a tight seal. Next heat the sides of your battery until the Heat Shrink Tube tightly contours to the ripples of the washers. Then, trim the excess leaving only 1/4" and heat until a tight seal is formed on the other end.
Step 10: Add Terminals
Now we're going to add our terminals. Plug in your Soldering Iron and wait until hot.
Secure your battery copper side up (the side you started with). You will then apply heat to the solder while holding it above the hole formed on the end of your battery. As it melts, press solder into the hole until full and finish with a small bead of solder on top.
Once cool, flip your battery over so the Zinc side is up. If you added additional washers this side will require quite a bit more solder. Repeat the process until full and top with a large bead of solder to signify the positive side. More or less solder can be added at this point to exactly match the correct length.
Step 11: You're Done! Time to Test It!
Your battery is now complete!
If you've done everything correctly you should be able to attach your Multimeter (same settings as before) and get a reading at or around 1.5 volts!
Compare it to a standard AA battery to see how you did!
*Troubleshooting: It is normal for your voltage to be high at first and then level out. If your voltage is slightly low, try pulling the battery from the ends to stretch it slightly. If your voltage is very low you may have a short (electrolyte square misaligned) or you may have stacked components in the wrong order.
Step 12: Use Your New Battery!
Your battery will fit into any standard AA slot and will provide the voltage you need to power all your favorite gadgets!
This homemade battery can power LED Flashlights, Portable Recording Devices, your Computer Mouse or any other device that requires AA batteries.
Now that you can make your own batteries at home you'll never need to buy expensive store-bought batteries again!!!
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