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The detailed introduction of ups battery
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The detailed introduction of ups battery

  • Author:
  • Origin:
  • Time of issue:2021-11-23
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(Summary description)The detailed overview of ups battery: The application, composition, category,characteristics,Calculation of battery capacity. All the knowledge about UPS power supply is here.

The detailed introduction of ups battery

  • Author:
  • Origin:
  • Time of issue:2021-11-23
  • Views:

(Summary description)The detailed overview of ups battery: The application, composition, category,characteristics,Calculation of battery capacity. All the knowledge about UPS power supply is here.

Information

What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 6 - 8)

 

3. Battery

 

3.1 Application of battery

 

The battery is an indispensable and important part of the DC power supply system.

 

The role of the battery in the system is mainly as an energy storage device. When the external AC power supply is suddenly interrupted, the normal operation of the communication equipment will be threatened, and the battery, as a backup protection of the system power supply, can provide uninterrupted power supply service for 1-20 hours or more.

 

Therefore, the battery is the last guarantee for system power supply and the last guarantee for maintaining normal communication.

 

UPS battery - INVT Power

 

The battery is an indispensable and important part of the DC power supply system - INVT Power

3.2 Battery composition

 

The battery is composed of positive and negative plate groups, electrolyte and battery tank. The active material on the positive plate is lead dioxide (PbO2), and the active material on the negative plate is spongy lead (Pb). The electrolyte is made up of distilled water and pure sulfuric acid in a certain proportion.

 

When a certain density of electrolyte is loaded into the electrolytic cell, the active materials on the positive and negative plates begin to undergo a series of chemical reactions with the electrolyte, and a 2.1V potential difference is formed on the positive and negative plates, which is the battery’s potential difference. Electromotive force (E). Therefore, when the battery is charging, the voltage of the external DC power supply should be higher than the electromotive force of the battery.

 

Electrochemical reaction during discharge

 

The total electrochemical reaction during battery discharge is as follows:

 

PbO2+2H2SO4+Pb—>PbSO4+2H2O+PbSO4

 

In the process of battery discharge, the active materials on the positive and negative plates are constantly transformed into PbSO4. Due to the poor conductivity of lead sulfate, the internal resistance of the battery increases after discharge. In addition, during the discharge process, since the lead sulfate in the electrolyte gradually changes to water, the density of the electrolyte gradually decreases. Therefore, the internal resistance of the battery increases and the electromotive force decreases. When the discharge is completed, the terminal voltage of the battery drops to about 1.8V.

 

The total electrochemical reaction during battery charging is as follows:

 

PbSO4+2H2O+PbSO4—>PbO2+2H2SO4+ Pb

 

During the charging process, the density of the electrolyte gradually increases, and the electromotive force of the battery gradually increases. In the later stage of charging, most of the active material on the electrode plate has been reduced. If you continue to charge with high current, the charging current can only play a role in decomposing water. In this way, a large amount of hydrogen will escape from the negative plate, and a large amount of oxygen will escape from the positive plate, and the battery will produce violent gassing.

 

3.3 Valve-regulated sealed lead-acid battery

 

3.3.1 Structural characteristics of valve-regulated sealed lead-acid batteries

 

Tightness.
 

Less maintenance.
 

Compact structure, small size, can be stacked and installed in multiple layers, and occupy a small area.
 

No flowing electrolyte (adsorption type), can be placed lying down.
 

The valve-regulated sealed battery has been charged before leaving the factory. After installation, it can be put into actual operation after a little supplement of electricity, which is more convenient to use.

 

3.3.2 Main technical performance and requirements of VRLA batteries

 

Capacity calibration: The battery capacity is expressed by the rated capacity of 10h under the conditions of an ambient temperature of 25°C and a cell discharge end voltage of 1.8V.
Floating charge service life: at an ambient temperature of 25℃, the operating life of 2V floating charge is 8 years, and that of 6V and above is 6 years.

 

Cycle life: the number of times when the depth of discharge is 100%
 

Floating voltage: 2.23~2.27V/pc.
 

Average charging voltage: 2.30~2.35V/pc.
 

Capacity preservation rate: The capacity preservation rate of the storage battery after 28 days is not less than 96%.
 

Balance of battery terminal voltage: A battery composed of several monomers, the highest and lowest difference between the open circuit voltage of each monomer is less than or equal to 20mV.
 

Voltage drop of battery connection bar: the battery is discharged at a rate of 1h, and the voltage drop of the connection bar between the two batteries measured at the roots of the two battery poles is ≤10mV.
 

Anti-acid fog performance: The battery should not escape acid fog during normal operation.
 

Explosion-proof performance: The battery should not explode when it encounters an open flame during the charging process.

 

3.3.3 Gel battery (valve-regulated sealed gel battery)

 

Gel battery - INVT Power


The battery uses a gel-like colloidal electrolyte, which is kept air-tight and liquid-tight during normal use. When the internal pressure exceeds the preset value, the safety valve automatically opens to release the gas. When the internal pressure decreases, the safety valve automatically closes to make it Sealed to prevent outside air from entering the battery. During the service life of the battery, there is no need to add electrolyte under normal use.

 

3.4 Use of valve-regulated sealed batteries

 

■Normal environmental conditions

 

Valve-regulated sealed batteries should work continuously under the following conditions:

 

Ambient temperature: -5℃~40℃.

 

Relative humidity: ≤90% (25℃).

 

Altitude: ≤1000m.

 

Installation method: indoor fixed installation.

 

■Charging voltage

 

Floating charge voltage; 2.23~2.27V/pc.

 

Equal charging voltage; 2.30~2.35V/pc.

 

Charge and discharge of valve-regulated sealed lead-acid battery

 

■Charge and discharge of valve-regulated sealed lead-acid battery

 

The sealed battery does not need to be initially charged before use, but it should be supplemented. The supplementary charging method and charging voltage should be carried out in accordance with the product technical manual. Under normal circumstances, the constant voltage and current limiting charging method should be adopted, and the supplementary charging current should not be greater than 0.2C10 (C10 = rated capacity of the battery)

 

■Equalizing charge of valve-regulated sealed lead-acid battery:

 

Under normal circumstances, when the sealed battery pack encounters one of the following conditions, it should be equalized (if there are special technical requirements, the product technical specification shall prevail), the charging current shall not exceed 0.2C10, and the charging method shall refer to the charging time-voltage comparison table .

 

There are more than two float voltages lower than 2.18V/unit.

 

Shelved it for more than three months. The depth of discharge exceeds 20% of the rated capacity.

 

■The criteria for the termination of charging of the sealed battery are as follows. If one of the following three conditions is reached, it can be regarded as termination of charging:

 

The charging capacity is not less than 1.2 times the discharged capacity.

 

The charging current in the later stage of charging is less than 0.01C (A).

 

In the later stage of charging, the charging current will not change continuously for 3 hours.

 

Several problems should be paid attention to in use and maintenance

 

■Ambient temperature of valve-regulated sealed battery

 

Temperature has a great influence on its service life. According to calculations, when the ambient temperature exceeds 25 degrees, every 10 degrees increase in temperature will reduce its service life by half. It is best to keep the ambient temperature around 25 degrees.

 

■Charging voltage of valve-regulated sealed battery

 

It has been charged when leaving the factory, so care should be taken to prevent short circuit between the poles during installation.

 

Recharge before use.

 

The level of charging voltage directly determines the working state and performance of the battery. Generally, the float charge voltage should be selected at 2.23~2.27V/only according to the manufacturer's instructions.

 

■The storage battery of the DC power supply system is generally set with two sets, and the storage battery of the AC uninterruptible power supply (UPS) is generally set with one set. When the capacity is insufficient, it can be connected in parallel, and the maximum number of battery groups in parallel does not exceed 4 groups

 

■Battery packs of different manufacturers, different capacities, different models, and different periods are strictly prohibited to be used in series or parallel.

 

Discharge current and battery capacity at different discharge rates

 

The following table exemplifies the capacity change of the same battery as the discharge rate changes. In the table, the capacity discharged at a rate of 10 hours when the electrolyte temperature is 25°C is used as the rated capacity of the battery

 

 
Discharge current and battery capacity at different discharge rates
Hours of discharge Battery capacity (% of rated capacity) Discharge current (% of rated capacity)
10-hour discharge rate 100 10
8-hour discharge rate 96 12
5-hour discharge rate 85 17
3-hours discharge rate 75 25
2-hours discharge rate 65 32.5

 

Battery discharge curve

 

Battery discharge curve - INVT Power

 

3.5 Calculation of battery capacity

 

Determine the size of the load current, determine the battery discharge time, and calculate the specific battery capacity.

 

Battery capacity calculation formula - INVT Power

 

Q: battery capacity (Ah);
K: safety factor, 1.25;
I: Load current (A);
T: discharge hours (h);
η: discharge capacity coefficient;

 

t: The lowest ambient temperature value of the actual battery location. When there is heating equipment, it is considered as 15℃; when there is no heating equipment, it is considered as 5℃;
 

α: battery temperature coefficient, when the electrolyte temperature is 25℃ as the standard, when the discharge hour rate is ≥10, take 0.006; 10> when the discharge hour rate is ≥1, take 0.008; when <1, take 0.01

 

Discharge capacity coefficient table

 

Lead-acid battery discharge capacity coefficient (η) table
Battery discharge hours (h) 0.5 1 2 3 4 6 8 10 ≥20
Discharge termination voltage (V) 1.65 1.70 1.75 1.70 1.75 1.80 1.80 1.80 1.80 1.80 1.80 1.80 ≥1.85
Discharge capacity system Acid-proof battery 0.38 0.35 0.30 0.53 0.50 0.40 0.61 0.75 0.79 0.88 0.94 1.00 1.00
Valve Controlled Battery 0.48 0.45 0.40 0.58 0.55 0.45 0.61 0.75 0.79 0.88 0.94 1.00 1.00

3.6 Factors affecting the service life of base station batteries

 

Frequent power outages, long periods of power outages, and irregular power outage periods in base stations cause frequent battery charging and discharging, which are the main reasons for the rapid decrease in battery capacity and shortened service life.

 

Switching power supply setting parameters are unreasonable, the base station battery undervoltage protection setting voltage is too low, and the reset voltage setting is too low, causing the battery to overdischarge or even deep overdischarge. On the other hand, it aggravates the sulfation of the negative plate of the battery, which is to increase the capacity of the battery. Decrease, another main reason for shortened service life.

 

The base station is used in a harsh environment. After the base station is out of power, the ambient temperature of the base station gradually rises due to the lack of air conditioning. Or, due to the failure of the air conditioner, the indoor temperature of the base station is too high, thereby reducing the service life of the battery.

 

After the base station is powered off, the battery is discharged to the termination voltage, and the battery is not recharged in time, which will also cause the battery capacity to decrease and the service life to shorten.

 

 

What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 1 - 8)- UPS types, functions and principles
What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 2 - 8)- UPS quality selection and configuration selection
What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 3 - 8)- UPS basic maintenance
What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 4 - 8)- 10 basic problems of UPS power supply
What is UPS? Why use UPS? All the knowledge about UPS power supply is here(Part 5 - 8)- communication power supply system

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