How to Place Batteries in Parallel

Placing multiple batteries in parallel increases their runtime.

Wiring batteries in parallel increases their capacity, or runtime, while maintaining the normal output voltage. For example, wiring two batteries in parallel typically doubles the average runtime of one battery, while wiring three batteries in parallel triples it. If you have an electrical device that drains its battery quickly, causing you to replace or recharge batteries frequently, buying a few identical batteries and wiring them in parallel may be a convenient solution.

Things You'll Need

• Batteries
• Pen
• AWG 16 wire
• Wire clippers
• Wire strippers
• Electrical tape

Instructions

1. Determine how many batteries you want to wire in parallel, based on how long you want your device to operate. Note that all batteries must be of exactly the same type, chemistry, voltage and state of charge.

2. Place your batteries in a row on a table or workbench. If you're wiring more than two batteries in parallel, number each battery using a pen. For example, if you're using four batteries, number them 1 through 4.

3. Calculate how many wires you will need to connect the batteries in parallel. You will need two short wires for each connection between two batteries, and two long wires to connect the wired batteries to your electrical device. Thus, if you intend to wire three batteries in parallel, you will need four short wires and two long ones.

4. Use the wire clippers to cut two wires that are long enough to reach from the last battery's terminals to the electrical device the batteries will power. Cut the remaining wires to reach from the terminal of one battery to the identical terminal of another.

5. Use wire strippers to remove about a quarter-inch of plastic insulation from the end of each wire.

6. Connect the positive battery terminals. Attach one end of a short wire to the positive (+) terminal of the first battery. Use a small piece of electrical insulating tape to hold the wire in place. Tape the opposite end of this wire to the positive terminal of the next battery. Repeat this process until you have connected all the positive battery terminals in numerical order.

7. Attach one end of the first long wire to the last positive battery terminal.

8. Connect the negative battery terminals. Tape one end of a short wire to the negative (-) terminal of the first battery. Tape the opposite end to the negative terminal of the next battery. Repeat this process until you have connected all the negative battery terminals in numerical order.

9. Attach one end of the second long wire to the last negative battery terminal.

10. Confirm that all taped wire connections are secure. Connect the loose ends of the two long wires to the appropriate terminals or wires of your electrical device.

Tips & Warnings

• It may be helpful to use a different wire color for positive and negative connections (e.g., red wires for positive, and black wires for negative).

• All batteries in a parallel circuit must have the same chemistry, voltage and level of charge. Failure to use identical batteries can result in overheating or explosion.

References

• New York City Amateur Radio Emergency Communications Service: Connecting Batteries in Series & Parallel
• Tisch School of the Arts: Batteries - How to Configure Them
• Battery University: Serial and Parallel Battery Configurations