Utilizing Parallel Lithium Battery Packs for Electric Vehicles: A Guide to Correct Usage

The capacity of a lithium battery pack significantly impacts the range of an electric vehicle. To extend the driving range, it often becomes necessary to connect two or more lithium battery packs in parallel and use them concurrently. In this article, we'll delve into the correct usage of parallel lithium battery packs and the potential consequences of improper handling.

Understanding the Risks of Directly Connecting Lithium Battery Packs in Parallel

First and foremost, it is crucial to emphasize that lithium battery packs should not be indiscriminately connected in parallel. The manufacturer's specifications for each lithium battery pack explicitly state this. In most cases,Battery recycling machine standard lithium battery packs should not be directly connected in parallel without additional precautions.

Directly connecting lithium battery packs in parallel results in a situation where the higher-voltage pack charges the lower-voltage pack. This voltage differential creates a substantial reverse current,cylindrical battery pack mahcine subjecting the Battery Management System (BMS) in both battery packs to high current loads. In severe cases, this can lead to BMS damage and even compromise the integrity of the lithium battery cells, potentially resulting in safety hazards such as fires and explosions.

Proper Techniques for Parallel Usage of Lithium Battery Packs

1. Utilizing BMS with Current Limiting Modules in Each Battery Pack:

In energy storage applications, especially for systems like communication base station battery packs, parallel use of lithium battery packs is common. For instance, a 48V 50Ah lithium battery pack can be created by connecting ten parallel 48V 50Ah units.cell stacking machine In this approach, each 48V 50Ah battery pack is equipped with a BMS featuring a current limiting module. These current limiting modules serve to balance the charge between battery packs by reducing the flow of charging current between them. As a result, the two battery packs charge each other gradually until their voltages align. Common current limiting module options include 10A and 20A.

The advantage of this method is its straightforward installation, as the BMS in each lithium battery pack comes with a current limiting module, allowing direct parallel connection. However, the downside is that the charging current should not exceed the current limit specified by the module. For instance, with a 10A current limiting module, the battery pack's charging current is capped at 10A. Charging above this limit would be restricted by the module.

2. Incorporating a Parallel Controller Module with Diodes:

Adding diodes to a parallel controller module effectively interrupts mutual charging between lithium battery packs by cutting off the current path. With this setup, current can flow only in the discharge direction, preventing current from flowing back into the battery pack. This approach efficiently manages mutual charging, safeguarding the battery packs. However, the drawback lies in the voltage drop introduced by the diodes, along with the heat generated and power consumption associated with their operation.

3. Implementing Parallel Hardware and Software Management Modules (Dual Battery Balancers):

This method represents a more advanced and recent development in managing parallel lithium battery packs. Parallel hardware and software management modules come equipped with protective devices to counter voltage imbalances and mitigate mutual charging issues. These modules encompass both software and hardware components that regulate the detection of battery voltages, logic judgment, and power supply balancing during charging and discharging operations.

The parallel management module facilitates independent control of multiple lithium battery groups. It constantly monitors input and output terminal voltages, ensuring that input voltages exceed output terminal voltages. In cases of voltage imbalance among the battery packs, the management module intelligently manages parallel discharge. It controls the discharge currents, allowing the battery pack with a higher voltage to provide more power while moderating the discharge of the pack with lower voltage. Through intelligent control via software and hardware, MOS transistors open and close, preventing battery packs from charging each other.

In conclusion, the proper use of parallel lithium battery packs in electric vehicles is essential for extending driving range and optimizing performance. Understanding the potential risks and employing the right techniques and modules, such as current limiting modules, diodes, or advanced parallel hardware and software management modules, ensures the safe and efficient operation of your battery packs. It's crucial to follow manufacturer guidelines and adhere to industry best practices to maximize the benefits of parallel lithium battery pack usage while mitigating risks.