The main difference between 3.7V lithium batteries and 3.6V lithium batteries lies in their nominal voltage and capacity. A 3.7V battery outputs 0.1V higher than a 3.6V battery. In practical use, as long as the appearance and wiring positions match, these batteries can generally be used interchangeably, especially in devices that allow voltage fluctuations.
Differences Between 3.7V and 3.6V Lithium Batteries
The only difference is in their rated voltage; there are no other distinctions. The discrepancy arises from different electronics industry standards. Sometimes, the voltage refers to the maximum working voltage of a single cell, and sometimes to the minimum working voltage.
- Working Voltage Range: The minimum working voltage of a lithium battery is about 3.2V, and the maximum is around 4.5V. Therefore, in practical terms, there’s no significant functional difference between 3.6V and 3.7V batteries.
- Nominal Voltage: Early lithium-nickel-cobalt-manganese (NCM) batteries had a nominal voltage of 3.6V due to technological limitations. With improvements in battery formulas and structure, 3.7V has become the standard.
- Capacity: Both batteries can range from hundreds to thousands of milliamp-hours. For example, a 3.6V battery may have up to 2200mAh, while 3.7V batteries may come in 1800mAh, 2200mAh, or 2600mAh. Larger capacities, such as 4400mAh or 6600mAh, are achieved by combining multiple cells.
Applications
Both 3.6V and 3.7V batteries are widely used in:
- Instruments and testing devices
- Medical instruments
- POS machines
- Laptops and portable electronics
They are favored for their high energy density and long cycle life.
Using in Series
3.6V and 3.7V 18650 lithium batteries can be connected in series for higher voltage output. Since their voltages are very close, this is generally safe. However, for safety, it’s important to ensure that the batteries in the series have similar voltage and capacity to prevent over-discharge or overcharging.
Why Different Voltages: 3.2V, 3.6V, and 3.7V?
- 3.6V & 3.7V: Both are polymer lithium batteries. The upper voltage limit is 4.2V, the lower limit is 2.6V, with 3.7V being standard.
- 3.2V: This is a lithium iron phosphate (LiFePO4) battery, known for high discharge capacity, long lifespan, and lightweight design. It’s commonly used in electric vehicles.
Lithium batteries can be divided into:
- Lithium metal batteries: Non-rechargeable, used initially in devices like pacemakers.
- Lithium-ion batteries: Rechargeable, widely used due to low self-discharge and stable voltage.
Additional Knowledge
3.8V vs 3.7V Lithium Batteries:
- The 3.8V battery can be charged slightly more fully.
- Most lithium batteries discharge from 4.2V to about 3.0V.
- Standard lithium battery voltage is around 7.4V for packs, so the difference between 3.7V and 3.8V is minimal.
Charging Considerations:
- Upper limit: 4.2V to balance capacity, lifespan, and safety
- Lower limit: Avoid discharging below 2.4V to prevent material degradation
- Cutoff voltage: 3.0V is ideal for releasing most capacity safely
- Current limits: Too high current may prevent lithium ions from entering storage grids, causing surface accumulation
Conclusion
While there is a nominal voltage difference between 3.6V and 3.7V lithium batteries, they can often be used interchangeably, especially in devices that tolerate minor voltage fluctuations. With technology improvements, 3.7V lithium batteries have become the mainstream choice due to higher energy density and better performance.
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