In this project, we’ll make battery packs essentially for free. If you need a lot, make a lot. If you need more voltage, add on more cells with couplers. If participants and students in your workshop or class all make their own, they can do it together, maybe even doing a manufacturing project to create many for future use.
For some time now, I have struggled with the expense and scarcity of battery holders. Costing anywhere from a dollar to three, they can raise the price point of a project, though they do look nice and work well. Since they are an item that most stores don’t carry, you will have to order battery packs for projects that you intend to do. If you’re planning a workshop or class with 25 people and want to use plastic battery holders, order ahead and pay up.
Plastic battery packs are also pretty easy to ruin if the ends of the wires are short-circuited accidentally or intentionally. A short circuit will heat up the batteries, which will then melt the plastic around one or both of the springs, causing the pack to fail. By making a battery pack, your participants and students can free themselves of the various barriers that purchased battery packs present for first run and experimental projects. For more formal projects, you or they may want to dig into the budget and buy some packs for a more polished look.
My first designs were done with cardboard from the recycling bin. I also made these with side by side arrangement. The way I am doing them these days is all in a line, which is probably not as sturdy or compact, but is definitely quicker. If you develop a better way of making these battery packs, please share pictures in the MAKE Flickr pool, and show us some links to them in action on projects.
Skills in this project:
- Trouble shooting and the design process
- Identifying a conductor and insulator
- Testing for electrical continuity
- Testing for voltage
- Designing for voltage
Materials you will need:
- Duct tape
- Tin foil
- Batteries, AA or AAA are good to start with
- Rubber band
- Stranded wire
- Utility knife
- Wire cutters/strippers
- Voltage/Ohm meter
Half an hour, after you get the hang of it, you can make one in less or make several all at once.
Students and participants will know how to make a 3 volt or more battery pack using readily available materials so that they can use them in electricity projects.
Gather your supplies.
Make the tubes
For each battery pack, cut 3 four inch strips of duct tape. One will be the coupler, two will be for end caps.
On each strip, cut a 1 inch square out of one end.
fold the strip in half, leaving exposed a 1 inch section at the end. Be careful that the other adhesive is not exposed (it could stick to the battery later)
Roll the strip onto a battery to make a tube. The exposed adhesive tab in the previous step should be the last section on.
Do this to make three of these tubes.
Make a coupler and end caps
Crunch up or fold up some tin foil and put it in one of the tubes. This will help ensure that there is good electrical contact between the batteries.
Put a battery into each side of the coupler. One should be positive end in, the other should be negative end in.
Slide a tube over each end of the exposed batteries.
Fold up a 1″ x 2″section of tin foil so that it makes a flat band of foil. Make two of these.
Fold over the end a couple of times so that it is a bit thicker.
Put this thicker end over the end of one of the batteries in turn.
Place a 3/8″ to 1/2″ wide section of tape over the end of the battery and end cap.
Hold the end caps in place with a piece of tape. You will want to remove the tape when the battery dies or needs to be recharged, so maybe fold over the end to make a pull tab.
Test for continuity
Put your meter on either the continuity setting or the ohms/resistance setting. When you touch the probes to an object that is a conductor like two ends of a stripped wire, you will have continuity: the meter will beep in the continuity setting or it will show numbers in the ohms/resistance setting. Electricity can travel between these two points. If you do not get continuity, such as on a piece of plastic or glass, or if one end of the wire is not stripped, electricity cannot travel easily between these two points. This is an insulator.
Increase your pack’s voltage
If your project needs 4.5 volts, 6 volts or more, you can add to the standard pack by slipping another battery onto the pack with another coupler. AA and AAA batteries are 1.5 volts each, so when you connect your batteries in series like this project, each battery you add boosts your voltage by 1.5 volts.
Cut two stranded wires, about 2″ to 4″ long.
Strip the ends about 3/8″.
On the end that will connect to the battery pack, spread the strands of the wire.
On the end that will connect to your circuit, twist the wires together. If you have access to a soldering iron, tin the wires to keep them together.
Test your pack and fix if needed
Put your meter in DC voltage mode and touch the probes to each of the wires.
The voltage for two batteries should read 3 volts. A (-) symbol in front of the number just means you have the probes on the battery backwards.
If you get 0 volts, you may need to press the pack together to get a better connection. In this case, you can hold the pack tighter together with a rubber band or carefully tape the caps so that they fit tightly.
Another problem that could give you 0 volts is that the batteries could be in the wrong direction. The negative of one battery has to touch the positive of the next battery.
Use your battery pack
You can use your new battery pack by twisting the wires on the pack to the wires on your circuit project.
You can also solder a 9 volt battery top onto your pack wires so you can use the standardized clip of the 9 volt system.
You can also twist your wires onto a connector cut from a power supply.
Teach your family to solder! Take a few pictures tagged as “MAKEcation” and put them in the MAKE Flickr pool by September 9th to enter to win a $100 Maker Shed gift certifiate!