What is a 3.7 v 18650 battery


The 3.7v lithium battery 18650 is a relatively special battery type in the lithium electronics industry, and its application range is very wide. This article introduces the characteristics of this battery and its advantages and disadvantages from three aspects.

Definition and Classification: The 3.7V lithium battery 18650 (lithium batteries 18650) is a model of nickel-cobalt-manganese lithium-ion battery. The term “18650” represents the capacity unit “ampere-hour.” Due to its high energy density and long cycle life, it is widely used in power tools, electric bicycles, and various portable electronic devices.


Voltage Characteristics: The 3.7V voltage is the same as the 3.6V lead-acid battery, but the working current is much smaller. The working current of 3.3~3.75V cadmium-nickel hydride batteries is much higher than that of 3.7V 18650 batteries.

Charge and Discharge Characteristics:

  • Capacity: 3.6-4.8 Ah (at 25°C), which is the nominal capacity of most alkaline dry batteries; 3.9-10.5 Ah (at 20°C).
  • Charging Time: It takes about 3~4 hours to fully charge at 25°C.
  • Self-Discharge Rate: When stored at room temperature, more than 50% of the charge remains after one year.

Advantages and Disadvantages:


  • Cost: Compared to lead-acid batteries of the same capacity, 18650 batteries are relatively low-cost and their prices are stable.


  1. Safety: Due to the lack of overcharge and over-discharge protection circuits, the safety of 18650 batteries is lower than that of other types of power or energy storage lithium batteries. Additionally, their internal structure makes them unable to withstand high current impacts and instantaneous high voltage pulses caused by short circuits. These factors increase the risk of explosion.
  2. Low-Temperature Performance: At low temperatures, electrode active materials can precipitate and form crystals, reducing conductivity and preventing normal charge and discharge operations, thus rendering the battery unusable (except for the 18651 model).
  3. Short Lifespan: Although the 18651 model can withstand temperatures as low as -40°C, high temperatures can still shorten its lifespan and even cause it to burst. For example, during summer, if a charger is left in a car exposed to sunlight, the internal pressure of the charger can become too high, leading to an explosion.

18650 lithium battery is more robust and stable in the international market, with a market share that leads other lithium-ion battery products in technology. It is widely used in a variety of industries, including consumer electronics, mechanical equipment, medical machinery, and more. It also shows strong potential in sectors such as service robots, AGV trucks, drones, and new energy vehicles. Additionally, it is prominently used in smartphones, tablets, laptops, electric toy cars, MP3/MP4 players, phone headsets, mobile chargers, model aircraft, and mobile phones.

18650 lithium battery has a balanced volume and safety coefficient compared to general lithium cobalt oxide materials and possesses stronger cycle characteristics. Due to technical reasons, its early nominal voltage was limited, and its application areas were also limited. With the gradual improvement of the formula and structure, the nominal voltage of the rechargeable battery has now reached or even exceeded the level of lithium cobalt oxide batteries. This makes 18650 lithium battery packs a preferred choice for many users today.

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