I recently put together a 3-string 12V battery pack using 1800mAh 18650 lithium batteries, and I want to share a straightforward method to make it yourself. Follow these steps carefully, and you’ll have a stable, functional battery pack in no time.
Materials Needed
- Three 1800mAh 18650 lithium batteries
- Nickel strips
- Hot glue gun
- Lithium battery protection circuit board (BMS)
- Soldering iron and solder
Step 1: Identify Battery Terminals
The first thing I do is check each battery for its positive (+) and negative (-) terminals. Most 18650 batteries have markings on the top and bottom, so make sure these are clearly visible. Correctly identifying the terminals will make assembly much easier.
Step 2: Arrange Batteries in Series
Next, I arrange the batteries in a series connection:
- Place the first battery with the positive terminal facing up.
- Flip the second battery so its negative terminal faces up.
- Place the third battery with the positive terminal facing up again.
This setup creates a proper series connection, adding the voltages together to get close to 12V.
Step 3: Secure the Batteries
To keep everything stable during soldering, I use a hot glue gun to fix the batteries together. Making sure they’re aligned properly prevents shifting and ensures easier soldering later.
Step 4: Connect the Batteries
Now comes the soldering part. Using nickel strips, I connect the batteries:
- Solder a nickel strip between the positive terminal of the first battery and the negative terminal of the second battery.
- Solder a nickel strip between the positive terminal of the second battery and the negative terminal of the third battery.
- Repeat underneath the batteries if necessary for extra stability.
Tip: Keep a steady hand while soldering to avoid short circuits or damaging the batteries.
Step 5: Mark Battery Voltage Points
It’s helpful to mark the voltage points on the battery pack:
- First nickel strip: 3.7V
- Second nickel strip: 7.4V
- Third nickel strip: 11.1V → serves as the 12V output terminal
This labeling makes it easier to connect the protection board correctly.
Step 6: Connect the Lithium Battery Protection Circuit Board (BMS)
Safety is key, so I always connect a protection circuit board. Here’s how I wire it:
- Solder the 3.7V terminal of the BMS to the 3.7V nickel strip.
- Solder the 7.4V terminal of the BMS to the 7.4V nickel strip.
- Solder the B- terminal of the BMS to the 0V terminal.
- Solder the 11.1V terminal of the BMS to the 12V output terminal.
Once connected, your 12V battery pack is ready to use. This pack provides a stable power supply for various electronic devices.
By following these steps, I successfully built a 12V lithium battery pack from three 18650 cells. This method is simple yet reliable, and I highly recommend it for anyone looking to assemble a compact, efficient battery pack.
If you try it yourself and run into any issues, feel free to leave a comment and we can troubleshoot together.
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