Differences between series and parallel connection of diving light batteries pack

15 May Differences between series and parallel connection of diving light batteries pack

We all know that in lithium batteries, series connections increase voltage while parallel connections increase capacity. How do we calculate the configuration of a lithium battery pack in terms of series and parallel connections, and how many cells it is composed of? Before calculation, we need to know the specifications of the cells used to assemble the lithium battery pack because the voltage and capacity of different cells vary. Common lithium cell types on the market include 3.7V lithium cobalt oxide, 3.6V ternary lithium, 3.2V lithium iron phosphate, and 2.4V lithium titanate, with capacities varying due to cell size, materials, and manufacturers.

Since the voltage and capacity of single cells are limited, in practical use, they need to be connected in series and parallel combinations to achieve higher voltage and capacity to meet the actual power supply requirements of devices.

Lithium Battery Series Connection:

• Voltage adds up, capacity remains the same, internal resistance increases.

Lithium Battery Parallel Connection:

• Voltage remains the same, capacity adds up, internal resistance decreases, and available power time extends.

Lithium Battery Series-Parallel Connection:

• The battery pack includes both parallel and series combinations to increase both voltage and capacity.

Series Voltage Calculation:

• A 3.7V single cell can be assembled into a battery pack with a voltage of 3.7*(N)V (N: number of cells), such as 7.4V, 12V, 24V, 36V, 48V, 60V, 72V, etc.

Parallel Capacity Calculation:

• A 2000mAh single cell can be assembled into a battery pack with a capacity of 2*(N)Ah (N: number of cells), such as 4000mAh, 6000mAh, 8000mAh, 5Ah, 10Ah, 20Ah, 30Ah, 50Ah, 100Ah, etc.

Considerations for Series-Parallel Connections of Lithium Batteries:

1. Do not use batteries of different brands together.
2. Do not use batteries with different voltages together.
3. Do not mix batteries with different capacities or new and old lithium batteries together.
4. Different chemical materials cannot be mixed, such as mixing nickel-hydrogen and lithium batteries.
5. When the battery power is insufficient, replace all the batteries.
6. Use a lithium battery protection board with corresponding parameters.
7. Choose batteries with consistent performance. Generally, lithium batteries used in series-parallel connections need cell pairing. The pairing standards are: voltage difference ≤10mV, internal resistance difference ≤5mΩ, capacity difference ≤20mAh.