Need To Know About Lifepo4 Batteries In Parallel

by John Smith Learner

Connecting lithium-ion batteries in parallel or series is not as simple as a simple series-parallel circuit. Several important factors must be considered to ensure the safety of batteries and the personnel working with them. Before diving into the necessary precautions, it's important to have a basic understanding of what parallel and series circuits are, their definitions, and their unique characteristics.

 

Lifepo4 batteries in parallel refers to connecting multiple cells together by connecting the positive and negative terminals to increase the total capacity of the battery pack.

Connect The Batteries In Parallel

In this configuration, each cell shares the load equally, resulting in an increased current output and thus an increase in total power. The output voltage of the battery pack remains the same as that of a single cell. Parallel connections are commonly used in applications that require large amounts of power, such as backup power supplies for buildings, off-grid solar power systems, and electric vehicles.

It is possible to connect LiFePO4 battery cells of different capacities in parallel to expand their capacity.

In fact, when connected in parallel, each group shares the current demand based on its total capacity.

For example, you have a 12V 230Ah pack with four 3.2V 230Ah LiFePO4 battery cells connected in series.

And you get 4 new 3.2V 280Ah LiFePO4 battery cells.

You can then connect these 4-cell LiFePO4 3.2V 280Ah batteries in series and connect them in parallel with the 12V 230Ah pack. This creates a new 12V 510Ah battery pack.

When planning in this way, the power consumption of the system should also be taken into account to avoid instantaneously high current requirements that may exceed the limits of smaller power cells.

In the example above, this is rarely the case, as the 200 amp unit can handle instantaneous currents of 200A-300A. Both packs can share 500A-600A instantaneous current. This rarely happens in real life.

Smaller packages such as 50Ah + 100Ah packages require accurate calculations. Since only one heavy duty microwave oven has an input power of up to 1500 watts, it will draw 125 amps from a 12 volt battery. Running other high power devices at the same time may exceed the 50Ah pack limit. Thus, for the 50Ah pack, the BMS is switched off.

So how to combine the battery must be considered in the context of the overall order.

In fact, many of my customers run different power cells in parallel to get more power, and they all work well.

However, there are a few things to keep in mind.

The voltage of the two batteries should be as close as possible when they are first connected.

They should have their own BMS.

Replacing/using the same AGW (size and length) minimizes the difference in voltage and resistance from the two packages.

For safety reasons, it is best to add a fuse to each group of batteries.

Comparison between series and parallel connection of LiFePO4 batteries

In this section, we will explain the similarities and differences between series and parallel connections.

Similarities:

Ability to increase overall battery performance: Series and parallel connections of LiFePO4 batteries can increase overall battery performance. In the case of a series connection, the output voltage of the battery pack increases, while in the case of a parallel connection, the power increases.

Use in various applications: series and parallel connections are used in various applications such as recreational vehicles, boats and solar homes. They can also be used in electric vehicles and other off-grid systems.

Variations:

Voltage output: Series connection of LiFePO4 batteries increases the overall output voltage of the battery pack. For example, if four 12 V batteries are connected in series, the output voltage of the battery pack will be 48 V. In contrast, the parallel connection of LiFePO4 batteries increases the total capacity of the battery pack, but the output voltage of the individual cell or battery remains the same.

Capacity: Parallel connection of LiFePO4 batteries increases the total capacity of the battery pack. For example, if 4 100Ah batteries are connected in parallel, the total capacity of the battery block will be 400Ah. In contrast, connecting LiFePO4 batteries in series does not increase the total capacity of the battery pack; It only amplifies the output voltage.

Efficiency: Parallel connection of LiFePO4 batteries is generally more efficient than series connection because each cell or battery charges and discharges independently. This ensures that if a cell or battery fails or is damaged, the entire pack will not be affected. Conversely, if a single cell or battery in a series-connected pack fails or is damaged, the performance of the entire pack can be affected.

Cost: Parallel connection of LiFePO4 batteries is generally more expensive than series connection due to the additional wiring and equipment required to ensure proper operation and integrity of the pack. However, the increased capacity and efficiency may justify the extra cost in some cases.

LiFePO4 batteries are connected in series and parallel

In conclusion, the choice between series and parallel connection of LiFePO4 batteries depends on the specific requirements of the application. If a higher voltage is required, a series connection is recommended. If more power is required, parallel connection is the best choice. While both configurations have their advantages and disadvantages, they both offer the potential to increase overall battery performance and are commonly used in a variety of applications such as RVs, boats, and solar homes. When choosing a configuration, it is important to consider factors such as voltage, power, efficiency, and cost to determine the best configuration for your specific needs.

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Created on Jul 27th 2023 06:45. Viewed 117 times.

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