How to Fuse Batteries in Parallel - Current sharing and cable selection

🎁 Free Diagrams: https://cleversolarpower.com 📖 My Best-Selling book on Amazon: https://cleversolarpower.com/off-grid... 105°C insulation cables: https://amzn.to/41i3Rym I recently got a great question from one of my subscribers: How do you fuse multiple batteries in parallel? In this video, I break it down step by step, explaining why individual fuses are important, how to calculate the correct fuse size, and what cable gauge you need for safe operation. When batteries are in parallel, each one shares the load. But if a battery develops an internal short, it can pull current from the other batteries. Without individual fuses, this could lead to overheating, melted cables, or even fire. A fuse on each battery prevents this by cutting off a faulty battery before it can cause damage. The rest of the system stays operational. For a 12V system with a 2000W inverter and three 100Ah batteries in parallel, each battery will deliver one-third of the total current. Since an inverter is about 90% efficient, the total current draw is 185A. Dividing this by three, each battery provides 62A. Applying two 1.25 safety factors (1.56), the fuse size becomes 100A per battery, and a 6 AWG (16mm²) cable is required. The main battery fuse should be 250A, with a 1/0 AWG (50mm²) cable. If you're using batteries of different capacities in parallel, they will contribute current based on their size. For example, with a 12V 100Ah battery and a 12V 200Ah battery, the total capacity is 300Ah, meaning the 100Ah battery provides one-third of the current, and the 200Ah battery provides two-thirds. The 100Ah battery needs a 60A fuse with a 6 AWG cable, and the 200Ah battery needs a 125A fuse with a 4 AWG cable. The main fuse should be 125A with a 4 AWG cable. If one battery fuse blows, the remaining batteries will take over, increasing their current load. This is why it’s important to monitor battery health regularly to prevent overloading. Checking voltage and current flow ensures all batteries are still contributing equally.