Battery Bank Calculator

Choose your target capacity and battery model to get the exact series/parallel configuration, total energy, BMS rating, and fuse size.

Target Capacity (kWh)

System Voltage

Battery Model

Series vs. Parallel

Series connections increase voltage while keeping amp-hours the same. For example, four 12V 100Ah batteries in series give you 48V at 100Ah (4.8 kWh). Series is how you match your battery bank voltage to your inverter's input voltage.

Parallel connections increase amp-hours while keeping voltage the same. Two 12V 100Ah batteries in parallel give you 12V at 200Ah (2.4 kWh). Parallel is how you add more capacity to your bank.

A 4S2P configuration means 4 batteries in series (to reach the target voltage) and 2 of those series strings in parallel (to reach the target capacity). That's 8 batteries total.

Important: Only parallel identical batteries — same brand, model, age, and state of charge. Mismatched batteries in parallel will cause imbalanced charging and shorten lifespan. Most LiFePO4 manufacturers recommend no more than 4 parallel strings.

Not sure which battery to buy? Our best LiFePO4 batteries for 2026 comparison covers tested capacity, BMS quality, and price per kWh. If you want to build a pack from raw cells instead, the DIY LiFePO4 battery bank guide walks through the entire process.