18650 3.7V 2000mAh Lithium-Ion Battery (7.4Wh) - Flat Top Cell

FREQUENTLY ASKED QUESTIONS (FAQ)

1. What does the number "18650" mean? It is the standardized physical size code for the battery. "18" means it is 18mm in diameter, and "65" means it is 65mm long. The "0" means it is cylindrical.

2. Is this a flat top or button top battery? This is a flat top battery. The positive terminal is flush and does not protrude.

3. Will this fit in a device that requires a button-top battery? Often, no. If a flashlight or device has physical reverse-polarity protection (plastic guards around the positive contact), a flat top battery will not be able to reach the contact point.

4. Does this battery have a built-in protection board (BMS)? No. This is an "unprotected" raw cell. You must use an external BMS board or plug it into a device with a built-in low-voltage cutoff to prevent over-discharging it.

5. Can I solder wires directly to the top and bottom of this battery? NO. Applying the high, sustained heat of a soldering iron directly to the steel casing will damage the internal chemistry and can cause the battery to vent or explode. You must use a dedicated battery spot-welder, or use a spring-loaded battery holder.

6. What is the nominal voltage? The nominal (average operating) voltage is 3.7V.

7. What is the voltage when it is fully charged? A fully charged 18650 reads exactly 4.2V on a multimeter.

8. How low can I safely drain this battery? You should never let an unprotected 18650 drop below 2.8V to 3.0V. Draining it below this will cause permanent chemical damage, severely reducing its capacity.

9. What does "discharge at 0.2C" mean? "C" is the total capacity. 0.2C means 20% of 2000mAh, which is 400mA. Drawing roughly 400mA continuously is the optimal efficiency rate to get exactly 2000mAh of runtime out of the cell per cycle.

10. Can my project draw more than 400mA? Yes. 18650 cells handle high currents very well. However, running it under a heavy, continuous load (like 2 Amps or 3 Amps) means the voltage will sag faster, and you may extract slightly less total capacity than the 2000mAh rating.

11. How do I charge this? You must use a dedicated 18650 lithium-ion charger cradle, or an integrated 4.2V lithium charging circuit module (like the TP4056).

12. Can I wire three of these together to get 11.1V? Yes. Placing three cells end-to-end (in series) gives you a 3S 11.1V pack. However, you must wire them through a 3S BMS protection board to ensure they charge and discharge evenly and safely.

13. Can I wire two together to get 4000mAh? Yes. Wiring them side-by-side (positive to positive, negative to negative) creates a parallel pack, keeping the voltage at 3.7V but doubling the capacity to 4000mAh.

14. Can I mix this 2000mAh battery with a 1200mAh battery in a custom pack? Absolutely not. Never mix batteries of different capacities, different brands, or different ages in the same series or parallel circuit. The weaker battery will be over-stressed, destroyed, and could catch fire.

15. What is the white ring on the top for? The white ring is an insulator. It prevents the positive center terminal from short-circuiting against the outer edge of the top face, which is connected to the negative casing. Do not remove it.

16. What should I do if the plastic wrapper tears? The entire metal cylinder under the wrapper is the negative terminal. If the wrapper tears, the side of the battery can easily short-circuit against a metal enclosure or another battery. Stop using it immediately and re-wrap it using custom 18650 PVC heat shrink tubing.

17. Is this battery waterproof? No. Keep it away from water and extreme humidity.

18. Can I use this in my vape/e-cigarette? Vaping devices draw massive, momentary spikes of current (often 15A to 30A). Generic 2000mAh cells are generally not rated for this extreme burst discharge and can be dangerous if used in mechanical mods. Stick to specialized, high-drain brand-name cells for vaping.

19. Why does the picture show a purple battery, but mine is pink/blue? Battery manufacturers frequently change their PVC wrapper colors depending on the production batch. The color of the wrapper does not affect performance.

20. How should I store this battery if I am not using it for months? Do not store it at 100% (4.2V) or 0% (dead). Store it in a cool, dry place at a "storage charge" of roughly 3.7V to 3.8V to significantly prolong its overall lifespan.