What is the difference between 3S and 4S lithium batteries?

The terms "3S" and "4S" refer to different configurations of lithium-ion or lithium-polymer batteries, specifying the number of cells connected in series within a battery pack. Each cell typically has a nominal voltage of about 3.7 volts. Let's break down the differences between 3S and 4S lithium batteries:

3S Lithium Battery:

"3S" stands for 3 Series. In a 3S lithium battery pack, three individual cells are connected in series. This means that the total voltage of the battery pack is the sum of the voltages of each individual cell. For cells with a nominal voltage of 3.7 volts, a 3S battery pack would have a nominal voltage of 11.1 volts (3.7V/cell x 3 cells).

4S Lithium Battery:

"4S" stands for 4 Series. In a 4S lithium battery pack, four individual cells are connected in series. The nominal voltage of a 4S battery pack, with cells each having a nominal voltage of 3.7 volts, would be 14.8 volts (3.7V/cell x 4 cells).

Key Differences:

Voltage:

The primary difference between 3S and 4S lithium batteries is their nominal voltage. A 3S battery has a lower nominal voltage than a 4S battery.

Applications:

The choice between 3S and 4S depends on the specific requirements of the application. Different electronic devices or applications may be designed to operate with a particular voltage range.

Power and Capacity:

While the voltage is different, the total energy capacity (measured in ampere-hours, Ah) of the battery pack depends on the capacity of individual cells and the configuration (parallel connections also impact capacity).

Charging and Discharging:

Charging and discharging characteristics can vary slightly between 3S and 4S batteries. It's essential to use the correct charger and management system designed for the specific battery configuration.

Weight and Size:

The number of cells in a battery pack affects its physical size and weight. A 4S battery pack, with an additional cell, might be slightly larger and heavier than a 3S battery pack.

Compatibility:

Electronic devices or systems designed for a specific voltage range should use batteries with the corresponding configuration (3S or 4S).

In summary, the main difference between 3S and 4S lithium batteries is the nominal voltage, which has implications for the overall performance and compatibility with specific applications. The choice between them depends on the voltage requirements of the device or system they are intended to power.