How to Connect Two 12 Volt Batteries in Series: A Comprehensive Guide

Connecting two 12-volt batteries in series is a useful method to double the voltage to 24 volts while maintaining the same amp-hour capacity. This setup is particularly beneficial in applications that require higher voltage, such as in RVs, solar energy systems, or for powering larger electrical motors. This guide will walk you through the process of connecting two 12-volt batteries in series, ensuring safety and efficiency.
12v lifepo4 battery series

Understanding Series Connection

When you connect batteries in series, the voltage of the batteries adds together, but the capacity (amp-hour, Ah) remains the same as one battery. This configuration is ideal when the requirement is for higher voltage rather than increased capacity.

Benefits of a Series Connection

  • Increased Voltage: Series connections are perfect for applications requiring higher voltage for operation.
  • Simplicity: Connecting batteries in series is relatively straightforward and doesn’t require complex wiring.
  • Compatibility: It allows for the use of standard
  •  to achieve 24 volts, which can be more cost-effective than purchasing a single higher-voltage battery.

Tools and Materials Needed

  • Two identical 12-volt batteries
  • High-quality battery cables
  • Wire connectors
  • Wrenches
  • Protective gloves and goggles

Step-by-Step Guide to Connecting Batteries in Series

  1. Preparation:
    1. Ensure both batteries are the same type, capacity, and ideally, have similar age and usage history. This uniformity helps to prevent issues like imbalanced charging.
  2. Safety First:
    1. Always wear protective gloves and goggles when working with batteries. Ensure all tools and the surrounding area are dry to prevent any short circuits.
  3. Position the Batteries:
    1. Place the batteries close to each other so you can easily access the terminals.
  4. Connecting the Batteries:
    1. Connect the positive terminal of the first battery to the negative terminal of the second battery using a suitable battery cable. This is the only connection that should cross between the batteries.
    2. The free negative terminal on the first battery will be where the system’s negative or ground wire is connected.
    3. The free positive terminal on the second battery will serve as a positive connection to your application.
  5. Securing the Connections:
    1. Ensure all connections are tight and secure. Use wrenches to tighten the connectors to avoid any loose connections, which can lead to a drop in efficiency or safety hazards.
  6. Final Setup Check:
    1. Double-check all connections for correctness. Make sure that the series setup does not have any short circuits or loose connections.
  7. Test the System:
    1. Use a multimeter to check the total voltage across the free positive and negative terminals. You should see a reading close to 24 volts, indicating a successful series connection.

Tips for Maintenance and Troubleshooting

  • Regularly Check Connections: Inspect the connections periodically for corrosion or loosening and clean them as necessary.
  • Monitor Battery Health: Keep an eye on the charging and discharging behavior. If one battery starts to fail, it can affect the overall system performance.
  • Balanced Charging: Whenever possible, charge the batteries individually with a 12-volt charger to maintain balance and prolong their lifespan.

Why Choose Himax Electronics?

Opting for Himax Electronics for your battery solutions offers several benefits:
  • Quality Assurance: Himax Electronics provides high-quality batteries and accessories that meet rigorous standards, ensuring reliability and performance.
  • Expert Support: Our team offers expert advice and support, helping you choose the right setup and maintain it effectively.
  • Innovative Solutions: We stay at the forefront of battery technology, offering products that meet the latest demands for efficiency and sustainability.

lithium battery-connection-tool


Connecting two 12-volt batteries in series is a practical and efficient way to increase voltage for various applications. By following the detailed steps outlined in this guide and adhering to safety protocols, you can successfully enhance your system’s voltage capability. For any battery needs or further assistance, consider Himax Electronics, where quality and customer satisfaction are our top priorities.