How Do You Calculate The Voltage And Capacity Of A Lithium Battery?

How do you calculate the voltage and capacity of a lithium battery? How to calculate how many batteries are connected in series and parallel?

1. To calculate the voltage and capacity of lithium batteries, we need to know the voltage of different cathode materials to calculate the rated voltage.

2. lithium battery pack is composed of battery cells by series and parallel connection

1, series connection (S): increase the voltage, the capacity remains unchanged.

For example: one lithium ternary cell rated voltage of 3.6V, capacity of 2600mAh, 10 lithium ternary cells in series, the battery pack voltage: 3.6v × 10 = 36V, capacity unchanged 2600mAH, the final is 36V 2600mAH.

For example: one lithium ternary cell rated voltage is 3.6V, capacity is 2600mAH, 10 lithium ternary cells are connected in parallel, the battery pack capacity: 2600mAH × 10 = 26000mAH, the voltage remains unchanged at 3.6V, the final is 3.6V 26000mAH.

For example: 1 lithium iron phosphate cell rated voltage 3.2V, capacity of 4000mAH, 10 lithium iron phosphate cells in parallel, the battery pack capacity: 4000mAh × 10 = 40,000mAh, the voltage remains unchanged 3.2V, the final is 3.2V 40,000mAh.

3,the battery cells are connected in series and parallel at the same time, the same calculation method, calculate the voltage, capacity on the line.

4, lithium battery pack power WH = battery pack rated voltage V × battery pack capacity AH.

For example: ternary battery pack 48V 15AH

Voltage: 3.7V×13=48.1V≈48V

Capacity: 2500mAh×6=15000mAh=15Ah

Electricity: 48v×15ah=720WH

Third, how to calculate how many cells in series

Ternary 48V, rated voltage of 3.6v for example: 48/3.6 = 13.3 ≈ 14series

Take ternary 48V, rated voltage is 3.7v for example: 48/3.7=12.9≈13series

Lithium iron 48V, rated voltage of 3.2V, for example: 48/3.2 = 15 series

For example 48V battery 

Example: Calculate with one ternary cell 3.7V:

13 cells in series (13 * 3.7V = 48.1V) Charging voltage: 13 * 4.2V = 54.6V

14 cells in series (14 * 3.7V = 51.8V) Charging voltage: 14 * 4.2V = 58.8V

Example: Calculate with one LiFePO4 cell 3.2V:

15 cells in series (15 * 3.2V = 48.0V) Charging voltage: 15 * 3.65V = 54.75V

16 cells in series (16*3.2V=51.2V) Charging voltage: 16*3.65V=58.4V

Charge to 4.2V (LiFe charging to 3.65V) with 0.5C multiplication rate at room temperature, and then switch to constant voltage charging.

Fourth, how to calculate how many cells are connected in parallel

Take 20Ah lithium battery pack as an example

The rated capacity of a single cell is 2500mah, 20Ah/2.5Ah = 8 parallel connections