Okay, here’s my blog post about my “18650 dual battery” project, written in a casual, first-person style:
So, I’ve been needing more juice for my portable projects. You know, those times when a single 18650 battery just doesn’t cut it? I decided to build a dual 18650 battery pack. Nothing fancy, just something to double my runtime.
First things first, I grabbed two 18650 cells. Made sure they were the same type and had similar voltage levels. You really don’t want to mix and match these things, it can get messy, and potentially unsafe.
Next, I needed a way to connect them. I opted for parallel connection. My goal is to have double the capacity, keeping the voltage. connecting them in series would increase voltage, not what I was looking for.
I got myself a simple 18650 battery holder, the kind with two slots. I Carefully soldered some wires, making absolutely sure the polarities were correct: positive to positive, negative to negative. Double-checked, triple-checked… you get the idea.
- Get two 18650 batteries
- Grabbed a dual-slot 18650 holder
- Soldered wires for parallel connection (positive to positive, negative to negative)
- checked that the voltages are the same.
After soldering, I used a multimeter to test the output voltage. It should be roughly the same as a single 18650 (around 3.7V to 4.2V when fully charged). If it’s significantly higher, something’s wrong, and I’d need to recheck my connections.
Once I was happy with the connections, I put the cells into the holder. Then I tested with small device that used to run on single 18650. Worked like a charm! It ran for about twice as long as before. Mission accomplished!
It’s a pretty basic setup, but it does the job. Remember, always be careful when working with lithium-ion batteries. They can be dangerous if mishandled. Use protection circuit is a good idea, which I will do in the future. Make sure you understand what you’re doing before you start soldering!
