1. What are series and parallel batteries?
1.1 Series Battery
Series battery refers to the positive terminal of one battery connected to the negative terminal of the next battery, each battery is connected to form a battery pack. Each cell in the battery has the same current and the total voltage is added.
1.2 Parallel Battery
A series battery is a battery pack that is formed by connecting the positive terminals of all batteries together and then connecting the negative terminals of all batteries together. The voltages of all cells in the battery pack remain constant and the total current is added.
2. Difference between series wired and parallel wired batteries
2.1 Series wiring and parallel wiring of the battery pack electrical characteristics of different
Series wiring is to connect all the batteries in the battery pack first and last, the total electric potential of the battery pack is the algebraic sum of the electric potential of all the individual batteries connected in series. At the same time, the total internal resistance of the entire battery pack is equal to the algebraic sum of the internal resistance of all individual cells.
Parallel connection is to connect the positive and negative terminals of the batteries together, when each battery in the battery pack is the same, the total electric potential of the battery pack is the same as the electric potential of a single battery. When the battery pack is connected in parallel with different batteries at the same time, the total electric potential of the battery pack is equal to the sum of the inverse electric potential of each battery. For the internal resistance of a parallel-connected battery pack, it is also necessary to use a special formula to calculate the total resistance of the inverse of the total resistance is equal to the sum of the inverse of the resistance of each piece of battery.
2.2 Advantages and disadvantages of series and parallel batteries are different
2.2.1 Advantages and disadvantages of series batteries
The most significant advantage of series battery packs lies in its ability to achieve a cumulative increase in voltage, and its simple installation, without the need for complex cable wiring and other installation procedures, can save a sum of wire costs. Secondly, the current flow through each cell is consistent when connected in series, which is critical for applications that require a uniform power source, helping the battery pack to achieve optimal new energy. And series-connected battery packs distribute the load across each cell, reducing the strain on individual cells and improving overall efficiency. Finally, series-connected battery systems have greater storage capacity.
However, the individual cells within a series-connected battery pack are more closely connected, and when one cell experiences a difference in charging or discharging rate, this may result in overcharging or undercharging of the entire battery pack, which can lead to a shorter life and reduced performance of the system. Similarly, when any of the cells in a series battery pack fails, it can cause the entire system to fail. In order to cope with the above problems, series-connected battery packs are usually equipped with external devices to balance their charging and discharging processes, which will also increase the cost to some extent.
2.2.2 Advantages and disadvantages of parallel batteries
Parallel batteries are able to increase the total power output of the system. Also, parallel battery packs are able to achieve greater current output without changing the voltage output as it is equally suitable for locations where no voltage adjustment is required. Secondly, because it is different from series connection, it can realize the uniform charging and discharging between each individual battery and keep the performance of each battery consistent. When one battery in a parallel battery pack fails, the other batteries can operate normally, rather than the entire system failing.
However, paralleling batteries does not increase the overall storage capacity of the system as series batteries do, and the current and current output of each battery may vary when the system is in operation, which can reduce its efficiency to some extent. Secondly, parallel battery packs require additional cable wiring and components, which can add an extra portion to the cost.
2.3 The number of cells that can be connected together differs between series and parallel batteries.
For series batteries, the number of cells that can be connected together depends on the electric potential of each cell and the voltage requirements of the connected load. It is worth noting, however, that there is a limit to the number of cells that can be connected in series, and when you connect too many cells in series at once, this can lead to an overall high voltage that can damage equipment and systems. Secondly, the number of batteries that can be connected in series will vary for different types of batteries. Generally speaking, lithium-ion batteries should be kept to a smaller number when connected in series, and lead-acid batteries will be able to reach a larger number in series.
For parallel batteries, the number of batteries that can be connected depends on a variety of factors, such as the type of battery, the capacity of each battery, and the specific application requirements. Generally speaking, however, it is best not to have more than 8 batteries of any type. This is mainly because connecting too many batteries in parallel can lead to many problems, such as uneven charging and discharging, and reduced overall battery pack life. Secondly, the more batteries are connected, the more upfront costs are spent on wiring and additional accessories, and the later maintenance costs will be correspondingly higher. Therefore, when increasing the number of batteries connected in parallel, it is recommended that you consult a professional engineer or electrician and do not blindly increase the number of batteries.
2.4 Series batteries and parallel batteries have different charging methods.
When charging series batteries, you need to connect the positive charger cable to the positive terminal of the first battery in the series battery pack and the negative charger cable to the negative terminal of the last battery in the series battery pack.
For parallel battery packs, you can connect the positive charger cable to the positive terminal of any battery, and the negative charger cable to the negative terminal of any battery, or you can use the same charging method as for series batteries.
2.5 Different service lifespan
Generally speaking, parallel batteries have a longer service life. First of all, we need to know that the service life of series and parallel batteries is mainly due to the different equalization between the two single batteries, which brings about different charging and discharging as well as daily use of the loss.
As the connection between each battery in series is relatively close, when one of the battery damage, the whole system will be changed, and often appear after a period of time to use the phenomenon of overcharging or undercharging occurs. The parallel battery has a certain degree of equalization between individual batteries, this equalization not only prevents overcharging and other phenomena when charging, but also prevents the battery in the use of the process due to the uneven loss of a single battery caused by the pressure, thus prolonging the overall service life.
3. Other issues on series and parallel batteries
3.1 How do series and parallel batteries affect the total power? Which connection makes up the greater total power of the battery pack?
Series batteries are able to keep the current constant and increase their voltage. The parallel battery can keep the voltage constant and increase the current. The total power is determined by both voltage and current. Obviously, both series and parallel connection will increase the total power of the battery. But specifically, the power of the battery also depends on its chemistry, size and other factors. In practice, a combination of series and parallel connections is generally used to build battery packs in order to achieve the specific power required by the customer.
3.2 Can series-parallel connections be created with several cells? How should series-parallel connections be created?
The answer is yes, it is possible to connect batteries in series and parallel at the same time, and this method is often used to meet specific customer requirements for increased voltage and capacity of the system.
First, you need to connect the batteries in parallel in pairs, this step is to increase the total capacity of the battery pack: connect all positive terminals together and all negative terminals together. Then you need to continue connecting each group of batteries in series in order to reach the specific voltage required by the customer: connect the positive terminal of the first group to the negative terminal of the second group, and continue in this way until the desired voltage is reached.
However, during this process, it is necessary to ensure that all cells used in series and parallel are identical to prevent disrupting the balance within the battery pack.
3.3 Series and parallel batteries are suitable for which case respectively
Series batteries are able to achieve a cumulative increase in voltage and are particularly suitable for use in equipment that requires high voltage power. Secondly, series batteries have a higher storage capacity, making them a better choice when you need a battery for emergency backup or when you need to power equipment off-grid for a long period of time.
Parallel batteries can increase the total power output of the system and keep the voltage stable, which is suitable for powering equipment that requires high power and stable voltage supply, such as uninterruptible power supply (UPS) systems or solar power generation systems. Secondly, each battery within the parallel battery pack is relatively independent, a single battery failure generally does not affect the overall energy supply system. Therefore, shunt batteries are suitable for certain critical equipment that requires a constant and stable power supply, such as: medical equipment, emergency communications and lighting equipment.
3.4 What happens when batteries are wired incorrectly?
When batteries are connected to form a battery pack, the wires that need to be connected are complex and numerous, but when these wires are connected incorrectly resulting in an incorrect battery connection, it may lead to the needed problems.
First of all, poor wire contact may cause the battery pack to overheat during operation, which can cause internal damage and reduce the life of the battery. It may also lead to a drop in the total voltage of the battery pack and an increase in the total resistance, reducing the efficiency of the batteries so that they are able to supply fewer hours of operation to the appliance. It may also cause a short circuit within the battery pack, damaging the batteries and causing a fire to occur.
When battery connections are not balanced, overcharging or undercharging may occur, reducing the capacity of the entire battery pack.
The connection of the battery pack is important not only to bring problems including performance and efficiency degradation, but also may pose a risk to the user’s life and property, especially for some battery packs that are used at high current and high voltage levels.
3.5 How to distinguish whether a strange battery is wired in series or in parallel?
When you get an unfamiliar battery, it is very important to distinguish whether it is wired in series or in parallel. There is a quick and effective way to distinguish between the two: you can first look at the appearance of the battery and find the two terminals of the battery. When batteries are wired in series, this means that there will be a potential difference between their positive and negative terminals at the terminals. If the batteries are wired in parallel, there will be no potential difference between their two terminals.
