How to Make a 12V Battery Pack

By Stephen Benham

If you need 12 volts to run an electrical appliance but only have 3- or 6-volt batteries nearby, you can connect your batteries in series to create a 12-volt battery pack. Connecting batteries in series combines the voltage from each battery, so joining four 3-volt batteries in series combines to make 12 volts. It’s easy to do and requires minimal tools.

Things You'll Need

  • Batteries
  • Electrical insulating tape
  • Small knife

Step 1

Check the voltage on your batteries. For example, if you have one 6-volt and two 3-volt batteries, once you wire them in series, you will have a 12-volt battery pack.

Step 2

Place the batteries together then wrap electrical insulating tape around them so they are held firmly together, forming a battery pack.

Step 3

Work out how many strips of electrical wire you need. For example, if you are using three batteries to make a 12-volt battery pack you need four wires: two wires to connect the batteries together and two wires to attach to your appliance.

Step 4

Cut each length of wire long enough that you can easily connect the batteries together and then connect the battery pack to your appliance. Strip ¼ inch of the plastic coating from each end of the wire using wire strippers or a small knife. If you’re connecting three batteries you will need to do this eight times.

Step 5

Connect one of the pieces of wire you intend to connect to your appliance to the positive terminal of your first battery (usually marked “+”). Either use the clips or screws on the battery terminal to hold the wire in place, or use electrical insulating tape to fasten the wire to the terminal.

Step 6

Connect a short piece of wire to the negative terminal of your first battery (usually marked “-“), then connect the other end to the positive terminal of your second battery.

Step 7

Connect a second piece of short wire to the negative terminal of your second battery and connect the other end to the positive terminal of your third battery. Repeat the process (negative to positive) as necessary if you are connecting more than three batteries to make your 12-volt battery pack.

Step 8

Connect your remaining piece of wire (the one that will connect to your appliance) to the last negative terminal of your battery.

Step 9

Connect the other end of the wire that’s connected to the positive terminal of your first battery to the positive terminal of your appliance.

Step 10

Connect the other end of the wire that’s connected to the negative terminal of your last battery to the negative terminal of your appliance. You have wired batteries in series to form a 12-volt battery pack.