When it comes to powering devices or systems that require more voltage or capacity than a single battery can provide, connecting batteries in series or parallel is a common practice. This article will guide you on why and how to connect batteries in series or parallel safely.

The Definition of Series Connection

When it comes to increasing the total voltage output of a battery pack, a series connection of LiFePO4 batteries is often used. This refers to connect multiple battery packs in a sequence to increase the total voltage output. In this configuration, the positive terminal of one battery is connected to the negative terminal of the next battery and so on until the desired voltage is achieved. This increases the total voltage while keeping same capacity. Bely batteries can be connected in series but we do not recommend this, it is better to use batteries with the correct voltage (we sell 24V, 36V and 48V batteries if required) due to the additional complexity involved with keeping batteries balanced. The maximum quantity of 12V battery in series connection should be 4 units which results in 51.2V at most.

The Advantages of Series Connection

Increased voltage output: By connecting multiple batteries in series, the overall voltage output of the battery packs increases, making it suitable for applications that require higher voltage.

Battery management: When charging or discharging batteries connected in series, the system can be easily managed by managing the voltages across each cell.

Efficient power source: Series connections can provide an efficient power source for devices that require high voltage and low current. This is because the voltage increases while the overall capacity remains the same.

The Disadvantages of Series Connection

Risk of over-charging/over-discharging: If cells in a series-connected battery pack have different capacities or ages, they may discharge at different rates, leading to an imbalance in the pack's voltage. This can result in overcharging of some cells, which can be dangerous and reduce the lifespan of the entire battery pack.

Reduced overall capacity: While the voltage output increases when cells are connected in series, the overall capacity of the battery system remains the same, meaning less energy can be stored.

The Definition of Parallel Connection

Connecting batteries in parallel involves connecting multiple batteries positive terminal to positive terminal and negative terminal to negative terminal. This increases the total capacity while keeping the voltage the same. For instance, connecting two 12V batteries in parallel will double the capacity but maintain a voltage of 12V. This is commonly used in most applications where high energy storage is required, such as off-grid solar power systems or electric vehicles where extended runtime is necessary.

The Advantages of Parallel Connection

Increased capacity: The primary function of parallel connection is to increase the overall capacity of the battery system while keeping the voltage output constant.

Easy management: Because each battery in a parallel circuit receives the same voltage, they can be charged and discharged individually without affecting other batteries in the system.

Scalability: Parallel connections allow for scalability by adding more batteries as required to increase the overall capacity of the system.

The Disadvantages of Parallel Connection

Lower voltage output: In a parallel-connected battery pack, the overall voltage output remains the same as that of an individual battery. Therefore, connecting batteries in parallel does not increase the overall voltage of the battery pack.

Increased risk of overcharging and overheating: Parallel connection increases the overall capacity of the battery system, making it easier to draw more current than the batteries can handle, leading to overcharging, overheating, and even fire hazard.

Less efficient energy storage: Parallel connections can lead to reduced efficiency since each battery's internal resistance affects the overall resistance of the system, which can reduce the amount of energy delivered to the load.

Matters Needing Attention in Parallel and Series Connections

When connecting LiFePO4 batteries in parallel, there are several matters needing attention to ensure optimal performance and safety:

Consistency: It's crucial to use batteries with the same specifications, including capacity and age in parallel connection. A mismatch of battery can lead to imbalances in charging and discharging, increasing the risk of battery failure.

Balance: Monitoring the state of charge of each battery is essential to maintain balance and prevent overcharging or undercharging of any individual battery. This helps ensure the longevity and safety of the entire battery pack.

Wiring: Proper wiring of the parallel connection is critical for efficient operation and safety of the battery pack. Incorrect wiring can lead to short circuits or other hazardous conditions.

When connecting LiFePO4 batteries in series, the following matters should be considered:

Consistency: It is necessary to use batteries with the same specifications, including capacity and age, in a series connection. A mismatch of battery can cause an imbalance in voltage distribution, leading to overcharging or undercharging of individual batteries.

Charging: Overcharging can occur in a series connection if one battery reaches its full charge before others. To prevent this, a battery management system (BMS) is recommended to monitor the voltage of each battery in series connection.

Safety: In a series connection, the total voltage output is increased, which can pose a higher risk of electrical shock. Proper insulation and grounding of the battery pack must be considered for safety purposes.

In conclusion, when building a solar power system or other off-grid systems, it is important to choose the right connection type for your batteries. Both series and parallel connections have their advantages and disadvantages, and the choice will depend on your specific needs and application. If high voltage output is required, then series connection is the way to go. If high capacity is required, then parallel connection is the best option. They both offer the ability to increase overall battery performance and are commonly used in various applications such as RVs, boats, and solar homes. When selecting a configuration, it's essential to consider factors like voltage output, capacity, efficiency, and cost to determine which configuration is best suited for your specific needs. Whether you're powering an RV, a solar power system, or an electric vehicle, understanding the difference of series and parallel connections will help you optimize performance and longevity.