How to Use 18650 Li-ion Battery x 2: Examples, Pinouts, and Specs

The 18650 Li-ion Battery is a rechargeable lithium-ion cell in a cylindrical form factor. Manufactured by Samsung, these batteries are known for their high energy density, long life, and stable discharge characteristics. They are commonly used in a variety of electronic devices, including laptops, flashlights, electric vehicles, and as part of battery packs for energy storage in portable power banks or larger systems.

• Portable electronics (laptops, cameras)
• Flashlights and headlamps
• Electric vehicles (bikes, scooters)
• Power tools
• DIY projects and custom battery packs
• Backup power supplies and UPS systems
• Hobby electronics and robotics (when used with appropriate battery management systems)

The 18650 Li-ion Battery does not have a pin configuration in the traditional sense, as it is a cylindrical cell. However, it has two terminals:

1. Battery Holder: Use a battery holder specifically designed for 18650 cells to ensure proper contact and safety.
2. Polarity: Always connect the positive terminal of the battery to the positive side of your circuit and the negative terminal to the ground or negative side.
3. Protection Circuit: Incorporate a protection circuit module (PCM) to prevent overcharging, over-discharging, and short-circuiting.
4. Charging: Use a dedicated Li-ion battery charger that can provide the correct charging voltage and current.
5. Series or Parallel Configuration: For higher voltage or capacity, batteries can be connected in series or parallel, respectively. Ensure all batteries are at the same state of charge before connecting them together.

• Battery Management: Always use a battery management system (BMS) when using multiple batteries to ensure balanced charging and discharging.
• Temperature: Charge and discharge within the recommended temperature range (usually 0°C to 45°C for charging and -20°C to 60°C for discharging).
• Storage: Store batteries at a 40-60% charge level in a cool, dry place if not used for extended periods.
• Handling: Avoid mechanical shock, puncture, or deformation of the battery.
• Disposal: Do not dispose of in fire or water. Recycle according to local regulations.

• Battery won't charge: Ensure the charger is functioning and the contacts are clean. Check for a required PCM.
• Short battery life: Verify that the battery is not being over-discharged or charged at an inappropriate rate.
• No output: Check for proper polarity and connection in the circuit. Ensure the battery is charged.

• Charging Issues: Use a multimeter to check the voltage of the battery. If below 2.5 V, the battery may be over-discharged and require a specialized charger to recover.
• Battery Life: Avoid leaving the battery fully charged or discharged for long periods. Regular use and proper storage extend battery life.
• Safety Precautions: If the battery is swelling, leaking, or has a strange odor, stop using it immediately and dispose of it properly.

Q: Can I charge 18650 batteries with a standard AA battery charger? A: No, you must use a charger specifically designed for Li-ion 18650 batteries.

Q: How can I increase the voltage for my project? A: Connect multiple 18650 batteries in series, but ensure they have the same capacity and state of charge.

Q: What is the life expectancy of an 18650 battery? A: The life expectancy varies based on usage, but typically they can withstand 300-500 charge cycles before capacity diminishes significantly.

Q: Can I use 18650 batteries in my device that requires AA batteries? A: No, 18650 batteries have a higher voltage and different size than AA batteries and should not be used as a substitute.

Q: How do I dispose of 18650 batteries? A: Take them to a battery recycling facility or a local collection point that accepts Li-ion batteries. Do not throw them in the trash.

Note: This documentation is for informational purposes only. Always consult the manufacturer's datasheet for the specific battery model you are using, as specifications can vary.