3.7V 150mAh LiPo Battery (402025) - Micro Lithium Polymer Cell with Protection PCB

FREQUENTLY ASKED QUESTIONS (FAQ)

1. What do the numbers "402025" mean? They indicate the standard physical size of the raw battery cell: approximately 4.0mm thick, 20mm wide, and 25mm long. (The final dimensions are slightly larger due to the protection board).

2. What is the nominal voltage of this battery? The nominal (average operating) voltage is 3.7V.

3. What is the voltage when fully charged? A fully charged 1S LiPo battery will read exactly 4.2V on a multimeter.

4. Does this battery have built-in protection? Yes, there is a tiny protection PCB hidden under the yellow tape at the top of the battery.

5. What does the protection circuit actually do? It protects the battery chemistry by preventing it from overcharging (which can cause fires), over-discharging (which ruins the battery), and short circuits.

6. Are the wires open-ended or do they have a plug? This specific listing provides 50mm open-ended (bare) wires so you can solder them directly to your project. Some reference images may show a plug, but stock ships open-ended.

7. Which wire is positive? The red wire is Positive (+), and the black wire is Negative (-).

8. Can I charge this by cutting a USB cable and wiring it to 5V? NO. You must never apply 5V directly to a LiPo battery. You must use a dedicated Lithium-Ion charger circuit (like the TP4056 module) to safely step the voltage down and manage the charge curve.

9. What does "discharge at 0.2C" mean? "C" represents the capacity of the battery. 0.2C means 20% of 150mAh, which is 30 milliamps (mA). To achieve the full 150mAh lifespan, your project should optimally draw around 30mA of continuous power.

10. Will it break if I draw more than 30mA? No, you can draw more current (like running a small motor), but pulling high current continuously means the battery will drain faster and you might get slightly less than the full 150mAh total capacity out of that specific cycle.

11. Can I power a 5V Arduino Uno with this? A standard Arduino Uno expects 5V to run smoothly. This battery only provides 3.7V. You would need a "Boost Converter" module to step the 3.7V up to 5V.

12. Can I use this with a 3.3V Raspberry Pi Pico or ESP32? Yes! 3.3V logic boards often pair beautifully with 3.7V LiPo batteries, usually utilizing a small 3.3V Low-Dropout (LDO) voltage regulator.

13. How long are the wires? The flexible wire leads are approximately 50mm (roughly 2 inches) long.

14. Can I cut the wires to make them shorter? Yes. CRITICAL WARNING: Always cut the wires one at a time. If you use metal scissors or wire cutters to snip both the red and black wires simultaneously, the metal tool will short-circuit the battery!

15. Can I wire two of these in series to get 7.4V? It is highly discouraged to wire individual, pre-protected LiPo cells in series to create a 2S pack. The two individual protection boards can conflict and cause charging/discharging failures.

16. Can I wire two of these in parallel to get 300mAh? Yes, but only if both batteries are measured with a multimeter and are at the exact same voltage before connecting them. If they are different voltages, one will rapidly dump energy into the other, causing damage.

17. Is this battery waterproof? No. The silver foil pouch is sealed, but the top circuit board and the wire connections are fully exposed to the elements.

18. Why does my battery look puffy or swollen? LiPo batteries puff up when they are old, damaged, or have been deeply over-discharged. If your battery swells like a balloon, do not charge it or use it. Safely recycle it.

19. What temperature is safe for this battery? Keep it away from extreme heat and freezing cold. Standard operating temperatures are usually between 0°C and 45°C. Never leave it in a hot car.

20. How should I store this battery if I am not using it for a few months? LiPo batteries should not be stored fully charged (4.2V) or fully dead (3.0V). Store them at a "storage charge" of roughly 3.8V in a cool, dry place (preferably inside a fire-resistant LiPo bag).