How to Wire LiFePO4 Batteries in Series

Wiring LiFePO₄ (Lithium Iron Phosphate) batteries in series is the best way to increase your system voltage (e.g. 12V → 24V → 48V), which can improve power efficiency and reduce current draw for large inverters and solar systems.

This guide walks you through safely wiring your batteries in series.

⚠️ Safety First

• Only wire identical batteries (same brand, voltage, capacity, and age).

• Batteries must be fully charged and balanced before wiring.

• Use DC-rated fuses, proper cable gauge, and wear PPE.

? What You’ll Need

• 2 or more LiFePO₄ batteries (e.g. two 12V 100Ah for 24V)

• Heavy-duty battery cables (based on amp load)

• Terminal lugs & crimping tool

• Inline fuses

• Battery switch (optional)

• Multimeter

• Cable management supplies

? Step-by-Step Instructions

Step 1: Fully Charge Each Battery

Ensure all batteries are 100% charged individually before wiring. This prevents voltage imbalance.

Step 2: Connect in Series

Connect the positive (+) terminal of Battery 1 to the negative (−) terminal of Battery 2.

If using more batteries, continue this pattern (positive to negative) until one positive and one negative remain free at the ends.

Step 3: Add Fuses

Install an inline fuse on the final positive cable that connects to your load or inverter.

Add individual fuses near each battery terminal if desired for added safety.

Step 4: Connect to Load or Charger

Connect your inverter/load/charger positive to the free positive (+) terminal at one end of the series.

Connect your negative cable to the free negative (−) terminal at the opposite end.

Step 5: Test the System

Use a multimeter to verify total voltage. For example:

• 2 × 12V batteries in series = ~25.6V (fully charged)

• 4 × 12V batteries in series = ~51.2V (48V nominal)

Monitor battery temperatures and voltages during initial use.

? Why Wire in Series?

• Increases voltage, allowing lower current draw (improved efficiency)

• Ideal for 24V or 48V inverters, solar charge controllers, or systems

• Allows thinner cables for the same power

❌ Do Not:

• Mix different battery sizes or brands

• Wire in series and parallel at the same time without a proper BMS

• Skip fusing or cable protection

? Example: 2 x 12V Batteries in Series

Goal: Create a 24V battery bank
Result: Same amp-hour (Ah) rating, double the voltage

? Wiring Diagram – 2 x 12V LiFePO₄ Batteries in Series

Here is a simple diagram to help you wire your batteries correctly: