DIY 12V High-Performance Outdoor Power Supply

I recently built a 12V high-performance outdoor power supply using 18650 ternary lithium batteries, and I want to share the steps in a way that anyone can follow. This power supply is compact, efficient, and perfect for outdoor use.

Battery Pack Configuration

Due to space limitations in the battery compartment, I used a total of 36 18650 ternary lithium batteries. I divided them into two groups, each assembled in a 3S6P configuration, and then connected the two groups in parallel for use.

Before starting assembly, I performed capacity sorting to ensure all batteries had similar capacity and internal resistance. This step is crucial for maximizing the performance and lifespan of the battery pack.

I selected cells with a 2 Ah capacity. With a 3S12P configuration, the full pack provides:

• Total Capacity: 24 Ah
• Voltage: 12V
• Energy Storage: ~0.28 kWh

This is sufficient for basic outdoor power needs.

Protection Board

I used a 3S protection board designed for 18650 ternary lithium batteries, rated at 40A with a maximum discharge rate of 5C. With a 24 Ah capacity, the battery pack can reach a maximum discharge of 100A, providing stable and reliable power output.

Connecting the Battery Groups

1. Connect cells with nickel strips within each group.
2. When wiring the protection board:
   • Negative terminal: Connect to the total negative of the battery pack
   • 4.2V terminal: Connect to the positive of the first series battery
   • 8.4V terminal: Connect to the positive of the second series battery
   • 12.6V terminal: Connect to the total positive of the battery pack

After wiring, I checked the protection board’s output voltage to confirm correct installation.

Repeat the same process for the second battery group.

Connecting Two Groups in Parallel

• Place insulating materials like kraft paper or epoxy boards between the two battery groups.
• Fix the groups in place with high-temperature double-sided tape.
• Connect the two groups in parallel using nickel strips.
• Apply high-temperature tape around the pack to reinforce fixation and insulation.

Installing the Battery Pack

Once the parallel connection is complete, I installed the battery pack into the case. I connected two wires from the protection board:

• A thinner wire for charging
• A thicker wire for discharge, which connects to the load

Installing the Inverter

Finally, I installed an 800W inverter to the battery pack. At this stage, the outdoor power supply is ready. It can easily power 220V electrical appliances, making outdoor activities much more convenient.

Building this power supply was a rewarding project. With careful assembly and attention to battery safety, anyone can create a reliable and compact outdoor power solution.

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