How to Connect Lithium Solar Batteries in Series and Parallel?

When you buy or DIY your own lithium solar battery pack, the most common terms you come across are series and parallel, and of course, this is one of the most asked questions from the BSLBATT team. For those of you who are new to Lithium solar batteries, this can be very confusing, and with this article, BSLBATT, as a professional lithium battery manufacturer, we hope to help simplify this question for you!

What is Series and Parallel Connection?

Actually, in simple terms, connecting two (or more) batteries in series or parallel is the act of connecting two (or more) batteries together, but the harness connection operations performed to achieve these two results are different. For example, if you want to connect two (or more) LiPo batteries in series, connect the positive terminal (+) of each battery to the negative terminal (-) of the next battery, and so on, until all LiPo batteries are connected. If you want to connect two (or more) lithium batteries in parallel, connect all positive terminals (+) together and connect all negative terminals (-) together, and so on, until all lithium batteries are connected.

Why do You Need to Connect the Batteries in Series or Parallel?

For different lithium solar battery applications, we need to achieve the most perfect effect through these two connection methods, so that our solar lithium battery can be maximized, so what kind of effect do parallel and series connections bring to us? The main difference between the series and parallel connection of lithium solar batteries is the impact on the output voltage and battery system capacity.

Lithium solar batteries connected in series will add their voltages together in order to run machines that require higher voltage amounts. For example, if you connect two 24V 100Ah batteries in series, you will get the combined voltage of a 48V battery. The capacity of 100 amp hours (Ah) remains the same. However, it is important to note that you must keep the voltage and capacity of the two batteries the same when connecting them in series, for example, you cannot connect a 12V 100Ah and 24V 200Ah in series! Most importantly, not all lithium solar batteries can be connected in series, and if you need to operate in series for your energy storage application, then you need to read our instructions or talk to our product manager beforehand!

Lithium Solar Batteries are Connected in Series as Follows

Any number of lithium solar batteries are usually connected in series. The negative pole of one battery is connected to the positive pole of the other battery so that the same current flows through all batteries. The resulting total voltage is then the sum of the partial voltages.

Example: If two batteries of 200Ah (amp-hours) and 24V (volts) each are connected in series, the resulting output voltage is 48V with a capacity of 200 Ah.

Instead, lithium solar battery bank connected in parallel configuration can increase the ampere-hour capacity of the battery at the same voltage. For example, if you connect two 48V 100Ah solar batteries in parallel, you will get a li ion solar battery with a capacity of 200Ah, with the same voltage of 48V. Similarly, you can only use the same batteries and capacity LiFePO4 solar batteries in parallel, and you can minimize the number of parallel wires by using lower voltage, higher capacity batteries. Parallel connections are not designed to allow your batteries to power anything above their standard voltage output, but rather to increase the duration for which they can power your devices.

Instead, lithium solar battery bank connected in parallel configuration can increase the ampere-hour capacity of the battery at the same voltage. For example, if you connect two 48V 100Ah solar batteries in parallel, you will get a li ion solar battery with a capacity of 200Ah, with the same voltage of 48V. Similarly, you can only use the same batteries and capacity LiFePO4 solar batteries in parallel, and you can minimize the number of parallel wires by using lower voltage, higher capacity batteries. Parallel connections are not designed to allow your batteries to power anything above their standard voltage output, but rather to increase the duration for which they can power your devices

This is How Lithium Solar Batteries are Connected Together in Parallel

When solar lithium batteries are connected in parallel, the positive terminal is connected to the positive terminal and the negative terminal is connected to the negative terminal. The charge capacity (Ah) of the individual lithium solar batteries then adds up while the total voltage is equal to the voltage of the individual lithium solar batteries. As a general rule, only lithium solar batteries of the same voltage and energy density with the same state of charge should be connected together in parallel, and wire cross-sections and lengths should also be exactly the same.

Example: If two batteries, each with 100 Ah and 48V, are connected in parallel, this results in an output voltage of 48V and a total capacity of 200Ah.

What are the benefits of connecting solar lithium batteries in series?

Firstly, series circuits are easy to understand and build. The basic properties of series circuits are simple, making them easy to maintain and repair. This simplicity also means that it is easy to predict the behavior of the circuit and calculate the expected voltage and current.

Secondly, for applications that require high voltages, such as a home three-phase solar system or industrial and commercial energy storage, series-connected batteries are often the better choice. By connecting multiple batteries in series, the overall voltage of the battery pack increases, providing the required voltage for the application. This can reduce the number of batteries needed and simplify the design of the system.

Thirdly, series-connected lithium solar batteries provide higher system voltages, which result in lower system currents. This is because the voltage is distributed across the batteries in the series circuit, which reduces the current flowing through each battery. Lower system currents mean less power loss due to resistance, which results in a more efficient system.

Fourthly, circuits in series do not overheat as quickly, making them useful near potentially flammable sources. Since the voltage is distributed across the batteries in the series circuit, each battery is subjected to a lower current than if the same voltage were applied across a single battery. This reduces the amount of heat generated and lowers the risk of overheating.

Fifthly, higher voltage means lower system current, so thinner wiring can be used. The voltage drop will also be smaller, which means that the voltage at the load will be closer to the nominal voltage of the battery. This can improve the efficiency of the system and reduce the need for expensive wiring.

Finally, in a series circuit, current must flow through all components of the circuit. This results in all components carrying the same amount of current. This ensures that each battery in the series circuit is subjected to the same current, which helps to balance the charge across the batteries and improve the overall performance of the battery pack.

What are the Disadvantages of Connecting Batteries in Series?

Firstly, when one point in a series circuit fails, the entire circuit fails. This is because a series circuit has only one path for current flow, and if there is a break in that path, the current cannot flow through the circuit. In the case of compact solar power storage systems, if one lithium solar battery fails, the entire pack may become unusable. This can be mitigated by using a battery management system (BMS) to monitor the batteries and isolate a failed battery before it affects the rest of the pack.

Secondly, when the number of components in a circuit increases, the resistance of the circuit increases. In a series circuit, the total resistance of the circuit is the sum of the resistances of all the components in the circuit. As more components are added to the circuit, the total resistance increases, which can reduce the efficiency of the circuit and increase the power loss due to resistance. This can be mitigated by using components with lower resistance, or by using a parallel circuit to reduce the overall resistance of the circuit.

Thirdly, series connection increases the voltage of the battery, and without a converter, it may not be possible to get a lower voltage from the battery pack. For example, if a battery pack with a voltage of 24V is connected in series with another battery pack with a voltage of 24V, the resulting voltage will be 48V. If a 24V device is connected to the battery pack without a converter, the voltage will be too high, which can damage the device. To avoid this, a converter or voltage regulator can be used to reduce the voltage to the required level.

What are the Benefits of Connecting Batteries in Parallel?

One of the main advantages of connecting lithium solar battery banks in parallel is that the capacity of the battery bank increases while the voltage remains the same. This means that the run time of the battery pack is extended, and the more batteries that are connected in parallel, the longer the battery pack can be used. For example, if two batteries with a capacity of 100Ah lithium batteries are connected in parallel, the resulting capacity will be 200Ah, which doubles the run time of the battery pack. This is especially useful for applications that require a longer run time.

Another advantage of a parallel connection is that if one of the lithium solar batteries fails, the other batteries can still maintain power. In a parallel circuit, each battery has its own path for current flow, so if one battery fails, the other batteries can still provide power to the circuit. This is because the other batteries are not affected by the failed battery and can still maintain the same voltage and capacity. This is particularly important for applications that require a high level of reliability.

What are the Disadvantages of Connecting Lithium Solar Batteries in Parallel?

Connecting batteries in parallel increases the total capacity of the lithium solar battery bank, which also increases the charging time. The charging time may become longer and more difficult to manage, especially if multiple batteries are connected in parallel.

When solar lithium batteries are connected in parallel, the current is divided among them, which can lead to higher current consumption and higher voltage drop. This can cause problems, such as reduced efficiency and even overheating of the batteries.

Parallel connection of solar lithium batteries can be a challenge when powering larger power programs or when using generators, as they may not be able to handle the high currents produced by the parallel batteries.

When lithium solar batteries are connected in parallel, it can be more difficult to detect defects in the wiring or the individual batteries. This can make it harder to identify and fix problems, which can result in reduced performance or even safety hazards.

Is it Possible to Connect Lithium Solar Batteries both in Series and in Parallel?

Yes, it is possible to connect lithium batteries in both series and parallel, and this is called a series-parallel connection. This type of connection allows you to combine the benefits of both series and parallel connections.

In a series-parallel connection, you would group two or more batteries in parallel, and then connect multiple groups in series. This allows you to increase the capacity and voltage of your battery pack, while still maintaining a safe and reliable system.

For example, if you have four lithium batteries with a capacity of 50Ah and a nominal voltage of 24V, you could group two batteries in parallel to create a 100Ah, 24V battery pack. Then, you could create a second 100Ah, 24V battery pack with the other two batteries, and connect the two packs in series to create a 100Ah, 48V battery pack.

Series and Parallel Connection of Lithium Solar Battery

A combination of a series and a parallel connection allows greater flexibility to achieve a certain voltage and power with standard batteries. The parallel connection gives the required total capacity and the series connection gives the desired higher operating voltage of the battery storage system.

Example: 4 batteries with 24 volts and 50 Ah each result in 48 volts and 100 Ah in a series-parallel connection.

Best Practices for Series and Parallel Connection of Lithium Solar Batteries

To ensure the safe and efficient use of lithium batteries, it is essential to follow best practices when connecting them in series or parallel. These practices include:

● Use batteries with the same capacity and voltage.

● Use batteries from the same manufacturer and batch.

● Use a battery management system (BMS) to monitor and balance the charge and discharge of the battery pack.

● Use a fuse or circuit breaker to protect the battery pack from overcurrent or overvoltage conditions.

● Use high-quality connectors and wiring to minimize resistance and heat generation.

● Avoid overcharging or over-discharging the battery pack, as this can cause damage or reduce its overall lifespan.

Can BSLBATT Home Solar Batteries be Connected in Series or Parallel?

Our standard home solar batteries can be run in series or parallel, but this is specific to the battery's use scenario, and series is more complex than parallel, so if you are purchasing a BSLBATT battery for a larger application, our engineering team will design a viable solution for your specific application, in addition to adding a sink box and high voltage box throughout the system in series!

There are a few things to keep in mind when using BSLBATT's home solar lithium batteries, specific to our series.

- Our Power wall batteries can only be connected in parallel, and can be expanded by up to 30 identical battery packs

- Our Rack-mounted batteries can be connected in parallel or in series, up to 32 batteries in parallel and up to 400V in series

Finally, it is important to understand the different effects of parallel and series configurations on battery performance. Whether it is the increase in voltage from a series configuration or the increase in amp-hour capacity from a parallel configuration; understanding how these results vary and how to adjust the way you maintain your batteries is critical to maximizing battery life and performance.