Rechargeable batteries: device, operation, operating principle and circuit

Autonomous power sources are one of the most useful inventions of mankind. What is a phone or radio that does not have rechargeable batteries installed ? The arrangement of many devices, as well as the conditions for their use, do not always provide for a permanent network power supply, therefore such sources of electricity make it possible to operate comfortably in virtually any part of the world. After a short introduction, let's get down to the article.

What is a rechargeable battery?

In a broad sense, this term means a device that, under certain conditions of use, can accumulate some kind of energy, while in others it can be used to meet the needs of the person.

Batteries accumulate electricity from an external power source, and then give it to connected consumers so that they can do their work. So, when the devices work, chemical reactions constantly occur between the electrolyte and the electrode plates. By the way, a similar design is placed in the banks, from which the batteries are formed. The device of these designs provides for the creation of a voltage, usually 1.2-2 V, which is very small. Therefore, to increase the performance of power sources, different types of connection are used.

How do I discharge batteries?

The power supply data device provides connection to plus and minus. They function as follows: when a load is connected to the electrodes (as an example we can consider a light bulb), a closed electrical circuit appears. It starts to flow discharge current. It is formed due to the motion of electrons, anions and cations. More detailed information about what and how it is, you can tell only on a concrete example.

Let's say that we have a battery where the positive electrode is nickel oxide, into which graphite was added to increase conductivity. For a negative plate, sponge cadmium was used. So, when the discharge goes, the active oxygen particles are released and fall into the electrolyte. At the same time, they separate parts that go as electricity (the same electrons). Then the active oxygen particles are directed toward the negative plates, where they oxidize cadmium.

Battery operation while charging

It is necessary to disconnect the load on the terminals of the plates. They are also fed, as a rule, with a constant voltage (but can be pulsating, depending on the case), which is larger than the size of the battery that is being charged. And the polarity should be the same. That is, the minus and plus terminals of the consumer and source must match. Note that the charger must necessarily have more power than there is in the battery to suppress the energy left in it and create an electric current, the direction of which will be the opposite of the discharge. As a result, the chemical processes that occur in the battery are also changing.

Let's look at an example from the previous article. Here, a positive electrode will be enriched with oxygen, and pure cadmium will be restored to a negative electrode. Summarizing, we can say that during the charge and discharge only the chemical composition of the electrodes changes. This does not apply to the electrolyte. But it can evaporate, which will negatively affect the battery life.

So, we have considered the principle of operation of any battery. Now let's find out how to improve their performance during operation.

Parallel connection

The magnitude of the current depends on a significant number of factors. First of all, this means the construction, the materials used and their dimensions. The greater the area of the electrodes, the greater the current they can withstand. This principle is used for the parallel connection of the same type of cans in batteries. This is done if it is necessary to increase the current value that goes to the load. But along with this, it is necessary to raise the power of the source of energy.

Serial connection

If we consider the banks, of which the batteries are made, then it must be said that they are, as a rule, in one housing. A similar type of connection is used to obtain large voltage values with less loss.

You can see the application of this design by disassembling car batteries that are lead-acid. It's worth noting that this type is used not only in the car battery device, it's just the most likely way to disassemble how this type of connection works. In such a case, care must be taken to ensure that there is no metal contact, and there is reliable galvanic bonding through the electrolyte. But this only needs to be understood with respect to this type. In other cases, the assigned connection task will be implemented differently.

Types of batteries

They differ due to their purpose, capabilities, realization and material. At the moment, modern production has mastered the production of more than three dozen types, which differ in their composition of electrodes, as well as with the electrolyte used. For example, li-ion batteries boast a family of 12 known models. Conventionally, the following types can be distinguished:

1. Lead-acid.
2. Lithium.
3. Nickel-cadmium.

These are the most popular representatives. But for understanding the possibilities, we suggest to familiarize yourself with the list of materials that can act as electrodes:

• iron;
• lead;
• titanium;
• lithium;
• cadmium;
• cobalt;
• nickel;
• zinc;
• vanadium;
• silver;
• aluminum;
• A number of other elements, which, however, are very rare.

The use of different materials affects the resulting output characteristics and, therefore, the scope of application. So, for example, li-ion batteries are used in computer and mobile devices. Whereas nickel-cadmium is used as a replacement for standard galvanic cells. Theoretically, all types of batteries can work with any load. The only question is how justified is such an application.

Main characteristics

We have already considered what batteries are, the structure of these structures, what they are made of. Now let's focus on what affects their operation. Important characteristics for us are:

1. Density refers to the characteristic of the ratio of the amount of energy to the volume or weight of the battery.
2. The capacitance is the value of the maximum battery charge that it can give during the discharge process, until the lowest voltage is reached. This indicator is expressed in ampere-hours or pendants. Energy capacity can also be indicated. It is measured in watt-hours or joules. The task of this capacity is to report the amount of energy that is given during the discharge until the minimum permissible voltage is reached.
3. The temperature regime affects the electrical properties of the battery. When there are serious deviations from the manufacturer's recommended range of operation, then there is a high probability of power failure. This is because the cold and heat affect the intensity of chemical reactions, as well as the internal pressure.
4. Self-discharge refers to the loss of capacity that occurs after the battery is charged when there is no load on the terminals. In many ways, this indicator depends on the design and can increase if the insulation is broken.

These are the characteristics of the batteries and provide the most interest for us. Of course, if you have to do something new and exclusive, previously unprecedented, you may need something else. But this is highly unlikely.

Electrode device

As an example, we take the lead plates. Although they were earlier. Modern plates are made of lead-calcium alloy. Thanks to this, low battery self-discharge is achieved (50% of capacity is lost in 18 months). This also allows you to economize on water (only 1 gram per ampere hour).

One can also find a hybrid design, where, in addition to lead, antimony is added to the positive electrode, and calcium is added to the negative electrode. True, in such cases, there is an increased water flow. To increase the resistance to corrosive processes, add tin or silver.

Electrodes are made with a lattice structure, they are covered with a layer of active mass. The principle of operation of the battery depends to a large extent on what material is used for the plates. We consider the lead, which are easy to learn, but we do not recommend them.

Electrolyte

We consider all the same lead-acid batteries. As the electrolyte in which they are placed, sulfuric acid most often appears. It has a certain density, which can vary depending on the battery level. In this case, the principle operates: the more, the higher. Over time, the electrolyte escapes, and the capacity of the battery pack drops. The service life is affected by the operation (safety). In batteries, the electrolyte can be of two types:

• Liquid;
• In the form of impregnated special material.

At the moment, the first type is the most common.

Battery operation

The use of batteries can be observed almost everywhere. Remember your mobile phones or uninterruptible power supplies for computers. As an example, you can also use a conventional flashlight (modern samples are increasingly manufactured with an integrated battery and are not designed for galvanic cells). And cars? The systems "stop-start" and regenerative braking work from accumulators, and they put forward high requirements to starting current, deep discharge and durability. As you can see, without these power sources, it is difficult to do without any person in modern life.

Battery Construction Diagram

We reviewed the basic information about these devices. Let's pay attention to such concept, as the circuit of the storage battery. After all, within the framework of the article on it went only in passing. The battery of the modern circuit, according to history, was first created by the French physicist Gaston Plant. The area of his creation exceeded 10 square meters! Modern batteries, in fact, are simply significantly reduced and slightly modified copies of its battery. The only visible element for a person is the body. It ensures the generality and integrity of the structure.