Maintenance of the hottest valve regulated lead-ac

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Maintenance of valve regulated lead-acid battery

because valve regulated lead-acid battery (VRLAB) has the following advantages:

it can be placed horizontally and stacked, and can be placed together with communication equipment to save space; The lean solution design eliminates the specific gravity measurement in maintenance, which is suitable for high current discharge; In general, hydrogen and oxygen are well combined and will not produce hydrogen; Charging will not produce acid gas and pollute the environment, etc. Therefore, it has been widely used by our company in the field of communication

when the valve regulated battery was just used in the early 1990s, it was called "maintenance free battery", which is actually misleading. In addition, the quality of the early remote valve regulated battery products was not high, and some failures of one kind or another often occurred in use

of course, with the development of computer technology, the continuous emergence of large-scale integrated circuit devices, and the continuous improvement of switching power supply and UPS power supply technology, the power supply system equipment has made great progress, and the safety and reliability of power supply have been greatly improved, and the workload of power supply system equipment maintenance has also been reduced. However, the valve regulated battery matched with the power system equipment still has some faults from time to time. Therefore, the maintenance of valve regulated battery is very important in both DC power supply system and AC/DC uninterruptible power supply system

then, how can we maintain the valve regulated battery under the current conditions? The author would like to talk about his personal views on this issue

first of all, the quality problems of valve regulated battery operation should be analyzed. The operation quality of valve regulated battery is determined by three aspects: product quality, installation quality and operation and maintenance quality. These three aspects should be said to be very important. Especially product quality. This is the key to maintain the good operation quality of valve regulated battery, which is related to all links in the production process of battery, that is, from manufacturing lead powder to packaging and warehousing. Therefore, the thickness and weight of the grid, the formula of the lead paste, the permeability of the diaphragm, the technical design of the safety valve, the filling method of the electrolyte, the control and synthesis method of the injection amount of the electrolyte, the shell material, the seal between the shell cover and the pole, and the seal between the shell cover and the shell should be strictly controlled

for installation quality, it also includes storage, installation, capacity experiment and other aspects. These aspects will directly affect the future operation and maintenance of valve regulated batteries. Therefore, attention should be paid to avoid collision during handling and storage. During installation, attention should be paid to the coincidence between the junction strip and the battery pole pile, and the uneven pole pile should be carefully leveled. When tightening the pole pile, the force used should not be too large or too small. If it is too large, the copper sleeve in the pole pile will overflow, and the force is too small, which will cause poor contact between the busbar and the pole pile. Therefore, it is best to use the wrench with over force tripping provided by the manufacturer in the installation, or use the corresponding kg wrench according to the reference kg force provided by the manufacturer. During installation, pay attention to the following aspects: first, make the length of positive and positive, negative and negative electrodes of each group of batteries between the battery and the DC screen as consistent as possible, so as to maintain the operation balance between battery packs in case of large current discharge; 2、 The connection between the positive and negative bus bars of the battery pack and the battery bus bar shall be firm and reliable; 3、 Do not forget to recharge the battery after installation

for maintenance quality, it is also an important aspect to ensure the normal operation of valve regulated battery. If the maintenance quality is high, the valve regulated battery can give full play to its efficiency and prolong its service life. Therefore, the power maintenance personnel should be engaged in the maintenance work on the premise of fully understanding the requirements put forward in the valve regulated battery product manual, and clarify the relationships and problems in the following aspects in the maintenance work

(1) relationship between temperature and capacity

the approximate standard given by GNB battery (valve regulated battery) on interconnection is: at 25 ℃, the capacity of battery is 100%; When the temperature is above 25 ℃, the capacity of the battery will be reduced by half for every 10 ℃ increase

the capacity of valve regulated battery changes with the change of temperature. Maintenance personnel must carefully adjust the discharge current of battery according to the change of actual temperature, and control the temperature of battery to keep it within 22 ℃ ~ 25 ℃

(2) the relationship between charging, discharging and life and capacity

a. the relationship between charging and life

the maintenance of valve regulated lead-acid battery needs to establish and implement an accurate charging system in order to achieve the optimal performance and longest service life of the battery [1]. A large number of research results at home and abroad show that the charging mode determines the service life of the battery, and some batteries are not so bad, It's better to say that the charging method is improper and damaged. At this convenience, many domestic battery manufacturers and scientific research institutions or schools have done similar experiments. For example, there is a unit that divides the battery into two groups for experiments. One group uses the ordinary constant voltage current limiting method to conduct the full capacity life test, and the other group uses the phased constant current charging method to control the charging capacity, and uses the short-term medium current impact method to conduct the capacity cycle life test at the later stage of charging. As a result, the cycle life of the two groups of batteries is quite different due to different charging methods, and the cycle life of the batteries with stage constant current charging method is longer. It can be seen that the constant voltage current limiting charging method, which is widely used at present, has considerable shortcomings, especially in the late stage of charging. Since the current rectifier equipment, especially the switching power supply, does not have constant current characteristics, it is still difficult to adopt the second charging method, so this problem needs to be further explored

in addition, at present, some scientific research departments are exploring the use of pulse charging to charge valve regulated batteries. The main process is to divide the pulse charging into one or several stages, and each stage has several pulse cycles. If the whole process is charging for 10min? Stop charging for 3min? Discharge 3S? Park for 1.75min. The final stage is to charge for 15min and stand still for several hours to cool the electrolyte, etc. It is said that this method is ideal and can eliminate sulfation [2]

b. relationship between discharge and capacity

as we all know, the discharge current with different magnification will make the battery have different capacity

the storage battery capacity configured in the DC power supply system of communication power supply is also different. There should be an accurate calculation of the storage battery capacity under the actual discharge current. It is worth noting here that the oxidation and reduction of lead sulfate formed under the condition of small current discharge is very difficult, because the size of lead sulfate particles formed under the condition of small current discharge is much larger than that under the condition of large current discharge, that is to say, the speed of crystal formation under the condition of large current is slower than that under the condition of small current, and the crystal will be oxidized and reduced quickly before it has time to grow, so the particles are relatively small. Under low current conditions, larger lead sulfate crystals are not easy to be reduced. If the lead sulfate crystal cannot be cleaned for a long time, it will inevitably affect the capacity and service life of the battery

(3) influence of imbalance on valve regulated battery

relevant research results show that: the distribution of alloy composition and structure in different parts of the grid is different, which will lead to the imbalance of electrochemical performance of the grid [3]. This imbalance will make the voltage difference in the floating charge and charge and discharge state, and will increase with the cycle of charge and discharge, and will increase with the charge The cycle of discharge increases this difference, forming the so-called "backward battery (battery failure)". At present, domestic standards require that the difference of the maximum floating charge voltage in a group of batteries should be ≤ 50mV, while the standard of developed countries is ≤ 20mV, so we should pay attention to and reduce the difference of battery voltage operation under floating charge

(4) thermal runaway phenomenon

due to the lean liquid design of the valve regulated battery, the electrolyte filled in the battery is adsorbed on the fiberglass board. When the charging current increases, it is necessary to release gas through the safety valve, resulting in the loss of water, increase of internal resistance, capacity attenuation and a large amount of heat during charging and discharging. If these heat cannot be diffused and the temperature increases sharply, it will form heat out of control

the causes of thermal runaway include not reducing the floating charge voltage in time, lax safety valve or too low valve opening pressure, etc. in the case of severe punishment of thermal runaway, if discharge, it may cause the instantaneous voltage drop of the battery and the temperature of the battery shell to rise to 70 ℃ ~ 80 ℃, so the problem of thermal runaway must be paid great attention to

through the above analysis, we have some understanding of the maintenance of valve regulated batteries. To do a good job in the maintenance of valve regulated batteries, we must do:

A. if conditions permit, the battery room should be equipped with air conditioning equipment and the temperature should be controlled between 22 ℃ and 25 ℃. This can not only prolong the service life of the battery, but also make the battery have the best capacity

b. in any case, the floating charge voltage of the battery should not exceed the floating charge value given by the manufacturer, and the value of the floating charge voltage should be adjusted at any time by using the voltage regulation coefficient ± 3mv/℃ according to the change of ambient temperature

c. in view of the influence of imbalance on valve regulated battery, the lower limit of floating charge voltage should be used for floating charge power supply

d. after the battery is unbalanced or deeply discharged, and when the battery runs for a quarter, the battery should be recharged in a balanced way. Pay attention to the change of ambient temperature during equalizing charging, and reduce the set value of equalizing voltage with the increase of ambient temperature. For example, if the ambient temperature rises by 1 ℃, the voltage value of equalizing charging needs to be reduced by 3MV

e. try to charge the "backward battery" by pulse charging to promote the recovery of the battery

f. careful maintenance. Before the valve regulated battery pack is put into operation, the voltage and internal resistance data of each single battery should be carefully recorded and properly stored as the original data. After half a year of operation, the operating data should be compared with the original data, and any abnormal conditions should be handled in time

g. when the valve regulated battery runs to 1/2 of its service life, it is necessary to appropriately increase the frequency of testing, especially for the single 12V battery. If the internal resistance of the battery suddenly increases or the measured voltage is unstable (especially two decimal places) and always changing, it should be treated as a "backward battery" immediately

h. where conditions permit, select single 2V valve regulated battery for UPS equipment on 40kvac

i. regularly check the safety valve of valve regulated battery, and carefully observe whether there are sprayed stains around the safety valve, so as to determine whether the safety valve is tightened or damaged

j. in the process of battery selection and procurement, we should fully understand the manufacturer's production process, manufacturing process, quality control means, as well as technical characteristics. If necessary, we can require the first capacity test to be carried out in the manufacturer to screen batteries with small differences

in short, in the communication maintenance work, we should pay attention to the maintenance of the valve, so add a clamping device to maintain the controlled battery

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