Despite several advances in battery technology, lead acid batteries are still the most popular due to their low costs and high initial current surge. Still, they don’t last for many cycles, costing you hundreds of dollars on replacements.
While acid batteries for applications like cars have precise specifications, you can make acid batteries at home to save plenty of money long-term. Here’s everything you need on how to make an acid battery by yourself.
How Does an Acid Battery Work
A lead acid battery consists of a negative electrode made of spongy or porous lead that facilitates the reaction. The positive electrode is made of lead oxide. Both electrodes are immersed in an electrolytic solution, usually sulfuric acid and water.
The battery has an electrically insulating but chemically permeable membrane to prevent the electrodes from coming into contact with each other. The structure is best explained in the image below.
During the discharge state, the lead from the negative terminal loses electrons to produce lead ions. Those react with the sulfate ions in the solution to form lead sulfate. At the positive terminal, lead oxide gains electrons to break into lead and oxide ions. The lead deposits on the positive terminal, whereas the oxide ions react with the hydronium in the solution to form water.
In contrast, the charging state reverses the process. The lead sulfate ions break down from electrolysis into solid lead fragments that deposit on the electrode. The water molecules in the solution also separate into hydronium and oxide ions that react to form sulfuric acid and lead oxide, respectively.
Components You Need for an Acid Battery
Now that you know how a lead acid battery works, you can determine the components you need to make it at home. Those include:
The solution carries the electrons and lets either electrode achieve the necessary reactions. A sulfuric acid solution with water can serve the role well, as it is strong enough to react with the lead ions immediately. However, it is also highly corrosive, so you should take some precautions when working with it.
The electrodes are necessary to maintain a potential difference and initiate the reaction losing and gaining electrons at the negative and positive terminals, respectively. Usually, you can use an alkaline earth metal and its oxide. They are easy to get your hands on, and you can shape the electrodes without using specialized tools. Lead is often the best bet.
You can’t insert the electrodes directly. It would help to have ground plates to separate the cells and electrodes. They are pretty inexpensive to order online, and you can get matching clamps and metal dies to hold them in place.
A robust and insulated battery case lets you contain the volatile chemicals within an isolated environment to keep them from reacting with the environment. You can build one for yourself, but it is best to get one from an old used battery to save on costs. Such cases already have slots for cells and fuses, saving time on creating them yourself.
In addition to everything mentioned above, you need the necessary electrical equipment like a hydrometer, a multimeter, pliers, screwdrivers, etc. The hydrometer helps you determine the appropriate concentration for the electrolyte before you dip in the electrodes.
How to Make an Acid Battery
Once you’ve gathered all the components, you can start building your acid battery at home. So, now you need to put on your insulating gloves and follow the procedure detailed below.
- Place the battery case on a firm, dry surface and clean it with a mildly acidic solution. Lime or vinegar should do the job. Ensure to wipe the interiors thoroughly, as any contaminants can disrupt the chemical reactions during use.
- Take the ground plates and make them into cells using the lead and lead oxide electrodes. Make sure to attach the positive terminal (lead oxide) first. Use the clamps and metal dies to hold them in place. Adjust the size of the electrodes using a grinding machine to ensure they fit in the battery slots.
- Attach the negative terminal (porous lead) into each cell and place the cells in the battery case. It is a delicate process as you have to secure the top part firmly while leaving the bottom part of the plates free. Use the correct size bolts and screws to tighten the cells. Don’t insert the fuse yet, as you need to work on the electrolyte first.
- Connect each cell in the series with cables and use a multimeter to detect any residual charges. If there is a current, check the connections or the cells once again before preparing the electrolyte.
- Use an insulating container to store some concentrated sulfuric acid and slowly add water. Let it cool down for 30 minutes. The solution should be 65% water and 35% acid. You can measure the exact concentration using the hydrometer.
- Once the solution cools down, gently pour it into the battery case. Close the lids on top of each section.
- Let the chemical reaction take place for a few minutes. After that, use a multimeter to check the voltage. It should show a full charge. For example, a 12V battery made up of four 3V cells should provide a potential difference of about 13.1V.
And that’s it. Congratulations! Your homemade battery is ready to use. Don’t forget to insert the fuses and take a few test trials before depending on them for real applications.
Safety Precautions When Making an Acid Battery
You’re working with some volatile materials when making an acid battery at home. So, applying a few security measures like the ones mentioned below is wise.
- Construct the battery in an open space, away from flammable materials and any pets or family members.
- Use insulating gloves, masks, and goggles throughout the whole process. Make sure that you wear boots, full-length jeans, and a shirt, not leaving much of your skin exposed.
- Always double-check the voltage before connecting the electrodes. Ground all the electrodes with residual charges.
- When pouring the electrolyte solution, use a thin channel to minimize spillage.
Making a lead acid battery at home is a cumbersome process. It will test your brain matter for electrical engineering. Yet, if you pull it off safely, it saves you hundreds of dollars on future replacements while limiting your e-waste footprint. We hope this guide helped you learn how to make an acid battery yourself. Do you still have a few burning questions? Feel free to share them in the comments below.