A storage battery is an electrochemical device that stores chemical energy and releases electrical energy when necessary. It uses a lead-based grid (also called a lattice) filled with spongy lead as the negative electrode and a lead-based grid filled with lead dioxide as the positive electrode, with dilute sulfuric acid (density 1.26-1.33 g/ml) as the electrolyte. During discharge, metallic lead, as the negative electrode, undergoes oxidation to produce lead sulfate; lead dioxide, as the positive electrode, undergoes reduction to produce lead sulfate. When charged with direct current, elemental lead and lead dioxide are generated at the two electrodes, respectively. After the power source is removed, it returns to its pre-discharge state, forming a chemical cell. Storage batteries can be repeatedly charged and discharged. A single cell has a voltage of 2V. A battery pack consists of one or more cells, commonly called a storage battery. The most common voltage is 6V, but other voltages include 2V, 4V, 8V, and 24V. For example, the storage batteries used in automobiles (commonly called car batteries) are six cells connected in series to form a 12V battery pack. Traditional dry-charged batteries (such as automotive and motorcycle dry-charged batteries) require the addition of distilled water after a period of use to maintain the dilute sulfuric acid electrolyte at a density of approximately 1.28 g/ml. Maintenance-free batteries, however, do not require the addition of distilled water until the end of their lifespan. According to a survey conducted by Jiaotong University Optics Valley editors among conventional battery manufacturers in the market:
Batteries can be classified in different ways, but broadly they can be divided into three main categories. The first category is based on the type of electrolyte, including: alkaline batteries, which primarily use potassium hydroxide solution as the electrolyte, such as alkaline zinc-manganese batteries (commonly known as alkaline manganese batteries), nickel-cadmium batteries, and nickel-metal hydride batteries; acidic batteries, which primarily use sulfuric acid solution as the electrolyte, such as zinc-manganese dry batteries (sometimes also called acidic batteries) and seawater batteries; and organic electrolyte batteries, which primarily use organic solutions as the electrolyte, such as lithium-ion batteries. The second category, classified by working nature and storage method, includes: primary batteries, also known as galvanic batteries, which are non-rechargeable batteries, such as zinc-manganese dry batteries and lithium primary batteries; secondary batteries, which are rechargeable batteries, such as nickel-metal hydride batteries, lithium-ion batteries, and nickel-cadmium batteries; storage batteries, which conventionally refer to lead-acid batteries, are also secondary batteries; fuel cell batteries, where active materials are continuously added from the outside when the battery is working, such as hydrogen-oxygen fuel cell batteries; and reserve batteries, where the battery is not in direct contact with the electrolyte during storage, and the electrolyte is added only when the battery is used, such as silver magnesium oxide batteries, also known as seawater batteries. The third category, classified by the positive and negative electrode materials used, includes: zinc series batteries, such as zinc-manganese batteries and zinc-silver batteries; nickel series batteries, such as nickel-cadmium batteries and nickel-metal hydride batteries; lead series batteries, such as lead-acid batteries; lithium-ion batteries and lithium-manganese batteries; manganese dioxide series batteries, such as zinc-manganese batteries and alkaline manganese batteries; and air (oxygen) series batteries, such as zinc-air batteries.
1. The main types of lead-acid batteries are as follows, and their applications are distributed as follows:
Starting batteries: primarily used for starting and lighting in automobiles, motorcycles, tractors, diesel engines, etc.
Stationary batteries: primarily used in communications, power plants, and computer systems as backup power for protection and automatic control;
Traction batteries: primarily used as power sources for various battery-powered vehicles, forklifts, loaders, etc.
Railway batteries: primarily used for starting and lighting in railway diesel locomotives, electric locomotives, and passenger cars;
Energy storage batteries: primarily used for storing electrical energy generated by wind, solar and other power sources.
2. UPS battery
UPS stands for Uninterruptible Power Supply because it can quickly switch to "inverter" mode during a power outage, preventing the loss of important files from computers that haven't had time to save due to a sudden power failure. It's not intended as a backup power source; if you only need power during a power outage, an inverter is sufficient. Most home UPS systems use maintenance-free lead-acid batteries.
3. Lithium iron phosphate battery
Lithium iron phosphate (LFP) batteries are the safest high-energy-density batteries in the lithium-ion battery family. The discharge voltage of LFP batteries is very stable, typically around 3.2V. The voltage changes more rapidly in the later stages of discharge (specifically, when the remaining 10% of capacity is available), with a cutoff voltage generally around 2.5V. Ambient temperature, especially low temperatures, affects the discharge capacity of LFP batteries: the discharge capacity at -20℃ is 45% of the room temperature capacity, at -10℃ it is 65%, at -5℃ it is 80%, and at 0℃ it is 90%. The change in discharge capacity between 0℃ and 20℃ is very small. LFP batteries exhibit better low-temperature performance than lead-acid batteries.
4. Super battery
A super battery engine starting power supply is a device that can quickly store energy and supply starting power to the internal combustion engine when the conventional battery used in the internal combustion engine fails and cannot be started.
The Jiaotong University Optics Valley solar storage battery represents the application of 'storage batteries' in solar photovoltaic power generation. Currently, four types are used: lead-acid maintenance-free batteries, ordinary lead-acid batteries, gel batteries, and alkaline nickel-cadmium batteries. The most widely used solar storage batteries in China are lead-acid maintenance-free batteries and gel batteries. These two types of batteries are well-suited for reliable solar power systems, especially unattended workstations, due to their inherent maintenance-free characteristics and low environmental pollution.
Ordinary lead-acid batteries require frequent maintenance and cause significant environmental pollution, so they are mainly suitable for use in situations where maintenance is possible or in low-end applications.
Although alkaline nickel-cadmium batteries have good performance in low temperature, overcharge and over-discharge conditions, their high price limits their application to specific applications.
With the widespread use of solar photovoltaic power generation systems, batteries, which are used in conjunction with these systems, are receiving increasing attention.
Jiaotong University Optics Valley solar batteries have the following characteristics
1. It has good deep cycling capability and excellent overcharge and over-discharge capability.
2. Long lifespan: The special process design and gel electrolyte ensure a long battery life.
3. Batteries that can be used normally under different environmental conditions, such as high altitude, high temperature, and low temperature.
Working principle of Jiaotong University Optics Valley solar storage battery
During the day, sunlight shines on the solar panels, causing the solar cells to generate a certain DC voltage, which converts light energy into electrical energy and transmits it to the intelligent controller. After overcharge protection by the intelligent controller, the electrical energy from the solar panels is sent to the storage battery for storage. Storage requires a storage battery, which is an electrochemical device that stores chemical energy and releases electrical energy when necessary.
The main components that make up a storage battery are as follows:
Anode plate (lead peroxide, PbO2) ---> active material
Cathode plate (sponge-like lead, Pb) ---> Active material
Electrolyte (dilute sulfuric acid) ---> Sulfuric acid (H2SO4) + Water (H2O)
Battery casing
isolation plate
Other (liquid plugs, caps, etc.)
Use and maintenance of Jiaotong University Optics Valley solar batteries
(1) Suitable working temperature: 15-20℃
(2) The method for connecting solar batteries is as follows: connect the positive terminals of the solar batteries to each other and the negative terminals to each other. This will double the capacity of the solar batteries while maintaining the same voltage as a single solar battery. The two terminals of the solar batteries must never be short-circuited (touched together).
(3) For newly installed or repaired solar batteries undergoing their first charge, a relatively long initial charge should be performed, using a current of 1/10 of the rated capacity. Before installation, the battery's capacity must be measured. If insufficient, charge the battery in a sunny location for at least 8-16 hours, or fully charge it using AC power first. Over-discharge should be strictly prevented. When charging normally with AC power, it is best to use a staged charging method: initially use a large constant current equalization charge, then maintain the equalization voltage for a specified time, and finally switch to a conventional constant voltage float charge method.
(4) Keep the battery itself clean. Apply petroleum jelly to the terminals of the installed solar battery to prevent corrosion.
(5) Configure online monitoring and management technology for solar batteries, perform online measurement and analysis of the internal resistance of solar batteries, detect battery defects in a timely manner, and carry out maintenance in a timely manner.
(6) In winter, prevent solar batteries from freezing and cracking. In summer, prevent them from being exposed to direct sunlight. Solar batteries should be placed in a well-ventilated and cool place.
The Jiaotong University Optics Valley off-grid photovoltaic power generation system is a power generation system that converts solar energy into electrical energy using the photoelectric effect. It typically consists of solar cell modules, a controller, a battery bank, and a DC/AC inverter. The solar cell modules convert solar energy into electrical energy to power the load or charge the battery bank; the controller protects the battery bank from charging and discharging; the battery bank stores electrical energy; and the inverter converts DC power into AC power. At night or on cloudy days when the solar cell modules are not working, the battery bank supplies power to the load.
Batteries can be categorized into two operating modes: cyclic use and float use. Cyclic use involves frequent charging and discharging, while float use involves frequent charging to compensate for capacity loss caused by self-discharge. VRLA batteries used in photovoltaic power generation systems operate under cyclic use.
To ensure high reliability of a battery system, the first step is to correctly select the battery. UPS and communication batteries differ in design: some batteries have better cycle characteristics; some are suitable for starting; some are suitable for low-temperature environments; and some are suitable for low-current discharge, etc. Jiaotong University Optics Valley reminds everyone that understanding the differences in manufacturing processes and applications among various batteries is crucial when selecting one. First, it's essential to fully understand the user's specific needs for the product. This includes factors such as backup power system capacity requirements, operating frequency, operating environment, key applications, lifespan, reliability requirements, instantaneous discharge rate, rectifier specifications, and other battery-related performance requirements. Secondly, it's necessary to understand the battery's electrical performance, including product design parameters (battery model, dimensions, rated capacity, rated voltage, weight, specific energy density, volumetric specific energy density, design life, number of positive and negative plates, positive and negative plate thickness ratio, electrolyte density, plate type, grid material, etc.), product electrical performance parameters, actual lifespan, installation and operating environment, performance and price of different models, and warranty periods for different types of products.
