Introduction
Lithium-ion batteries are a popular choice for powering a wide variety of electronic devices due to their high energy density and long life. It is a common practice to connect lithium-ion batteries in series to increase the total voltage. In fact, every battery pack we sell consists of a group of batteries connected in series (and often in parallel). In this guide, we will walk you through the steps to safely connect lithium-ion batteries in series to create a higher voltage battery pack for your project.
Please note that when you connect batteries in series you increase the voltage of the system. For example, connecting two 12 volt 100 amp hour Renewed Power Packs in series will create a 24 volt 100 amp hour battery. The total capacity is determined by the lowest capacity battery in the string (the so-called "barrel effect"). So if you connect a 12v 50Ah battery in series with a 12v 100Ah battery, the result will be a 24v 50Ah battery. Do not connect batteries of different capacities in series.
Safety First
Working with lithium-ion batteries requires special attention to safety. Always use batteries from a reputable manufacturer and understand the specific requirements and limitations of the battery you are using. Make sure your workspace is well ventilated and wear proper safety gear, including gloves and safety glasses. See our safety page for more information.
Example of connecting batteries in series. Here is a video by YouTube user Michael Sewanaku. Link to video.
Materials Needed:
Lithium-ion battery
Insulated wire
Battery holder or battery pack
Multimeter
If using a single battery, you will also need:
Battery Management System (BMS)
Wiring or nickel ribbon
Soldering iron and solder and/or spot welder
Steps
Choose a battery:
Use lithium-ion batteries with the same capacity and voltage rating.
For example, do not connect our 12v 100Ah battery in series with a 12v 20Ah battery.
Understand battery orientation:
Identify the positive (+) and negative (-) terminals on each battery. The positive terminal is usually red and the negative terminal is black.
Ensure proper alignment to prevent accidental shorts.
Determine voltage requirements:
Calculate the total voltage required for your application.
Make sure the voltage does not exceed the maximum rated voltage of the device.
Wiring in series:
Connect the positive terminal of one battery to the negative terminal of the next battery.
Continue this series connection until the desired voltage is reached.
Soldering connections:
Use a soldering iron to secure the connection.
Apply solder evenly to ensure a strong and reliable connection.
Installing a battery management system (BMS):
A BMS helps monitor and balance individual cells to prevent overcharging or over-discharging.
Connect the BMS to each battery in the series according to the manufacturer's instructions.
Insulating connections:
Slip heat shrink tubing over each solder connection.
Use a heat gun to shrink the tubing, providing insulation and additional structural support.
Testing voltage:
Use a multimeter to measure the total voltage of the batteries in series.
Make sure it matches the total voltage you calculated.
Securing the battery pack:
Place the wired batteries in a secure battery holder or battery pack.
Make sure the battery pack is well insulated and not subject to physical stress.
Conclusion
Connecting lithium-ion batteries in series requires careful attention to detail and adherence to safety guidelines. Always refer to the specifications provided by the battery manufacturer and use a BMS to monitor and protect the battery pack. By following these steps, you can create a reliable high-voltage power supply for your electronics projects.
Source
Battery University - "BU-304a: Safety Issues with Lithium-ion Batteries" Battery University
