Correctly connect and parallel the battery

Correctly connect and parallel the battery

17:21:38 | category: power supply, battery, and charging | font size subscription

Source: Portable product design Author: isidorbuchmann
It sounds very simple to connect the battery in series and in parallel. However, you can avoid unnecessary problems by following some simple rules.

In the battery pack, multiple batteries are connected in series to obtain the required operating voltage. If you need higher capacity and greater current, you should connect the battery in parallel. There are also some batteries that combine the series and parallel methods. The battery of a laptop may be to connect the four 3.6v lithium-ion batteries with a total voltage of 14.4 v. Then, the two batteries connected together are connected in parallel, the total power of the battery pack can be increased from 2000 mA to 4000 mA. This method is called "four strings and two parallel", which means that two batteries are connected by four batteries in parallel.

A battery is generally used in watches, storage for backup, and cell phones. The nominal voltage of a nickel-based battery is 1.2 V, the alkaline battery is 1.5 V, the silver oxide battery is 1.6 V, the lead acid battery is 2 V, and the lithium battery is 3 V, the nominal voltage of the lithium-ion battery is 3.6 V. Using lithium ion polymers and other types of lithium batteries, its rated voltage is generally 3.7 v. If you want an uncommon voltage like 11.1 V, you have to connect the three-member batteries together. With the development of modern microelectronics technology, we can use a 3.6v lithium-ion battery to power cellular phones and low-power portable communication products. In the 1960s S, mercury batteries, which were widely used in photometers, have now completely withdrawn from the market for environmental protection considerations.

The nominal voltage of the nickel-based battery is 1.2v or 1.25 v. There is no difference between them except for market preferences. For most commercial batteries, the voltage of each battery is 1.2 V; for industrial battery, Aviation Battery and military battery, the voltage of each battery is still 1.25 v.

Series

High-power portable devices are generally powered by battery packs connected by two or more batteries. If a high voltage battery, conductor and switch are used, the size can be very small. Medium-price industrial power tools use batteries with a voltage of 12 V to V, while advanced power tools use batteries with a voltage of 24 V to 36 V for greater power. The automotive industry eventually raised the ignition battery voltage of the starter from 12 V (actually 14 V) to 36 V, or even 42 V. These batteries are composed of 18 lead acid batteries in series. In early hybrid cars, the battery pack used for power supply has a voltage of 148 v. Compared to the battery pack used by new models, the voltage is as high as 500 V to V, most of which are nickel-based chemical batteries. A 400 V nickel metal hydrogen battery is a series of Nickel-Saving Metal hydrogen cells. Some hybrid cars have also been tested with lead acid batteries.

The 42 V battery is expensive, and it generates more arcs on the switch than the 12 V battery. Another problem caused by the use of a high-voltage battery pack is the possibility of failure of a certain battery in the battery pack. This is like a chain. The more batteries are connected together, the higher the chance of this situation. If a battery is faulty, the voltage will decrease. At the end, the disconnected battery may interrupt the delivery of current. Replacing the "bad" battery is not easy, because the old and new batteries do not match each other. In general, the capacity of the new battery is much higher than that of the old battery.

Let's look at an instance of a battery pack. The Third battery only produces a voltage of 1.2 V instead of a normal V (figure 1 ). As the operating voltage drops, it reaches the endpoint of discharge faster than the normal battery pack, and its use time is also greatly shortened. Once the power supply is cut off because the voltage is too low, the remaining three batteries that are still intact cannot output the stored power. At this time, the battery section 3 shows a large internal resistance. If there is a load at this time, the output voltage of the entire battery chain will be greatly reduced. In a set of serial batteries, a poor-performance battery is like a plug-in blocking a pipe, which will generate great resistance and stop the current flow. Section 3 The battery is also short-circuited, which will reduce the voltage of the terminal to 3.6 V, or disconnect the battery link and cut off the current. The performance of a battery depends on the performance of the worst battery in the battery pack.

Parallel Connection

To get more power, you can connect two or more batteries in parallel. In addition to connecting the battery in parallel, another way is to use a larger battery. This method is not applicable to all situations because it is limited by the available battery. In addition, large-sized batteries are not suitable for the shape specifications required for dedicated batteries. Most of the chemical batteries are

It can be used in parallel, while lithium-ion batteries are most suitable for parallel use. A battery pack consisting of four batteries in parallel, with a voltage of 1.2 V and a current and running time increased to four times.

Compared with battery series, the battery parallel circuit has less impact on high impedance or "open circuit" battery. However, the parallel battery pack reduces the load capacity and shortens the running time. This is like an engine that only starts three cylinders. The damage caused by a short circuit is greater because the faulty battery quickly consumes power from other batteries and causes a fire (figure 2 ).

Series-parallel

When using the series-parallel connection method, the design is flexible and the standard battery size can be used to achieve the required rated voltage and current (Figure 3 ). Note: The total power will not change because of different battery connection methods. The power is equal to the voltage multiplication current.

For lithium-ion batteries, the series-parallel connection method is very common. The most common type of battery pack is 18650 (diameter: 18mm, Length: 650mm ). It has a protection circuit that can monitor each battery connected together, so its maximum actual voltage is 14.4 v. This protection circuit can also be used to monitor the status of each battery in parallel.

Household batteries

The connection method of battery series and parallel connection mentioned above is for rechargeable battery packs. The battery in these battery packs are permanently welded together. In addition to attaching several batteries to the Battery room where the battery is installed, the rules described above also apply to household batteries. When connecting several batteries, you must follow the following basic requirements:

● Keep the connection points of the battery clean. There are a total of eight connection points (the connection point from the battery to the Battery room, and the connection point from the Battery room to the next battery) when four battery units are connected in tandem ). Each connection point has a certain resistance. Increasing the connection point may affect the performance of the entire battery pack.

● Do not mix batteries. When the battery is insufficient, replace all batteries. The same type of battery is used in tandem.

● Do not charge non-rechargeable batteries. When a non-rechargeable battery is charged, hydrogen may be generated, which may lead to an explosion.

● Note the polarity of the battery. If the polarity of a battery is reversed, the voltage of the entire battery is reduced, rather than increased.

● Remove the fully powered battery from the suspended device. Old Batteries are prone to leakage and corrosion. Alkaline Battery is less serious than carbon and zinc battery.

● Do not put all the batteries in one box, which may lead to short circuits. Short-circuit battery may cause fever and fire. Put the discarded battery in a small plastic bag, insulated from the outside.

● The battery pack similar to an alkaline battery can be thrown into a common waste bin. However, it is best to send the used battery to the regeneration cycle for processing.