How to Wire LiFePO4 Batteries in Parallel

Wiring LiFePO₄ (Lithium Iron Phosphate) batteries in parallel is a great way to increase the total amp-hour (Ah) capacity of your power system while maintaining the same voltage. This setup is popular in caravans, RVs, 4WDs, and off-grid solar systems where extended run-time is needed.

Follow this step-by-step guide to safely wire your batteries in parallel.

⚠️ Important Safety Notes Before You Begin

• Only wire batteries of the same brand, capacity, age, and state of charge.

• Always use fused cabling, PPE (Personal Protective Equipment), and tools rated for DC work.

• Make sure all batteries are fully charged and disconnected from any load or charger before wiring.

? What You'll Need

• 2 or more LiFePO₄ batteries of the same specs (e.g. 12V 100Ah)

• Quality battery cables (minimum 4 AWG or thicker depending on your current draw)

• Terminal lugs and crimping tool

• Inline fuses or a fuse block

• Battery switch (optional but recommended)

• Multimeter

• Cable ties or conduit (for cable management)

? Step-by-Step Instructions

Step 1: Fully Charge All Batteries

Charge each LiFePO₄ battery to 100% individually to ensure they are balanced. This prevents uneven load distribution after wiring.

Step 2: Connect the Positives Together

Use appropriately rated battery cable to connect the positive (+) terminal of Battery 1 to the positive (+) terminal of Battery 2.
Repeat for additional batteries.

? Tip: Use a busbar if connecting more than two batteries for a cleaner setup.

Step 3: Connect the Negatives Together

Now connect the negative (−) terminal of Battery 1 to the negative (−) terminal of Battery 2.
Again, repeat for additional batteries.

Step 4: Add a Fuse or Circuit Breaker

Place an inline fuse on the main positive cable close to each battery (optional but safest).
Install a main fuse where your positive cable runs to the load or inverter.

Step 5: Connect to Load/Charger

Connect your load/inverter positive to one battery's positive terminal (ideally opposite end of the battery bank).
Connect your load/inverter negative to the opposite end of the battery bank’s negative.

✅ This is called "diagonal wiring" and ensures even current distribution.

? Check Your Work

• Use a multimeter to confirm total voltage (should match a single battery’s voltage, e.g. 12.8V for a 12V setup).

• Ensure no cable is heating up under load.

• Monitor the system during first use to ensure all batteries discharge evenly.

? Why Wire in Parallel?

• Increases runtime: 2× 12V 100Ah batteries = 12V 200Ah system

• Same voltage: Your inverter or DC appliances work as usual

• Scalable: Easily expand capacity later

❌ Do Not:

• Mix different brands, capacities, or battery health levels

• Combine old and new batteries

• Wire batteries without fuses or proper gauge cable