How to Wire Batteries in Series | The Battle Born Educational Series

The Battle Born Educational Series | Wiring & Installation Fundamentals

Wiring batteries in series is how you increase system voltage in a lithium power system.

This configuration is commonly used when building 24-volt or 48-volt systems, where higher voltage allows for more efficient power delivery and supports higher-demand applications.

What Series Wiring Does

In a series connection, the positive terminal of one battery is connected to the negative terminal of the next.

This increases voltage while keeping amp-hour capacity the same.

For example:

• Two 12-volt batteries in series = 24 volts
• Four 12-volt batteries in series = 48 volts

In both cases, the amp-hour capacity remains unchanged.

For standard Battle Born Batteries, the maximum series configuration is four batteries, or up to 48 volts.

Confirm System Compatibility First

Before wiring batteries in series, it is critical to confirm that your system is designed for the higher voltage.

This includes:

• Inverter
• Charger
• Solar charge controller
• Any other major electrical components

All of these must be rated for the voltage you plan to build. Connecting batteries in series without matching system components can lead to improper operation or equipment damage.

Step-by-Step Series Wiring

The process of wiring batteries in series is straightforward when done correctly.

1. Start with matched batteries
   Use the same model and amp-hour rating for all batteries in the series string. This ensures balanced performance.
2. Pre-charge batteries
   Before connecting, charge each battery individually to an absorption voltage of approximately 14.4 volts. This helps ensure all batteries are balanced before being placed into a series configuration.
3. Connect positive to negative
   Use properly sized cables to connect the positive terminal of one battery to the negative terminal of the next.
4. Establish system connections
   After completing the series connections, the remaining open terminals become your main system connections:
   1. The open negative at one end
   2. The open positive at the other

These terminals connect to your system and deliver the full series voltage.

Expanding Capacity with Series Strings

If additional capacity is needed, you can connect multiple series strings in parallel.

This allows you to:

• Maintain the desired system voltage
• Increase total amp-hour capacity

When doing this, it is important to keep wiring consistent across all strings to ensure balanced current flow.

Use Proper Components and Cable Sizing

As with any battery system, proper cable sizing is critical.

Higher voltage systems typically operate at lower current for the same power, but connections still need to be:

• Properly sized
• Secure
• Consistent in length

This helps maintain efficiency and ensures safe system operation.

Avoid Mixing Batteries

It is important to use the same battery model and capacity throughout a series string.

Mixing batteries with different specifications or significantly different ages can lead to imbalance. This can impact performance and reduce overall system reliability.

The Bottom Line

Series wiring is a clean and effective way to increase system voltage.

By connecting batteries positive to negative, you can build 24V or 48V systems that support higher power demands and improved efficiency.

When done correctly, with matched batteries and compatible system components, series wiring provides a reliable foundation for higher-voltage lithium power systems.

Next, we walk through how to wire batteries in parallel to increase capacity and extend runtime while maintaining the same system voltage. Read: How to Wire Batteries in Parallel

Or, explore the full series at the Battle Born Academy and build your knowledge from the ground up.