Batteries are widely used in daily life, and can be divided into traditional lead-acid liquid-filled batteries and maintenance-free batteries. Because the batteries use lead-calcium alloy as the grid, the amount of water decomposition generated during charging is small, and the amount of water evaporation is also low. , and the casing adopts a sealed structure, and the sulfuric acid gas released is very little, so it has the advantages of no need to add any liquid, docking the wiring pile head, and long power storage time compared with the traditional battery. Batteries have a life cycle, different usage conditions, different environments, and different service life. Today, let’s understand what reasons will affect the service life of the battery?
1.Deep discharge
The depth of discharge has a great influence on the cycle life of the battery. If the battery is often deeply discharged, the cycle life will be shortened. Because the deep discharge of the battery with the same rated capacity means that it is often charged and discharged with a large current, and it cannot be recharged in time when it is discharged with a large current or is often in an undervoltage state. The sulfate particles produced are large, and the active material of the plate cannot be used If it is fully utilized, the actual capacity of the battery will gradually decrease in the long run, which will affect the normal operation of the battery. Since solar photovoltaic power generation systems are generally not prone to overcharging, long-term power deficit is the main reason for battery failure and shortened life in solar photovoltaic systems.
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2.Discharge rate
It is generally stipulated that the capacity of the 20-hour discharge rate is the rated capacity of the battery. If the discharge rate is lower than the specified hour, the battery capacity higher than the rated value can be obtained; if the discharge rate is higher than the specified hour, the released capacity must be It is smaller than the rated capacity of the battery, and the discharge rate also affects the terminal voltage of the battery. When the battery is being discharged, the electrochemical reaction current is preferentially distributed on the surface closest to the main solution, resulting in the formation of lead sulfate on the electrode surface and blocking the interior of the porous electrode. When the discharge current is high, the above problems are more prominent, so the discharge current becomes larger, the capacity given by the battery is smaller, and the terminal voltage value drops faster, that is, the discharge termination voltage value decreases with the increase of the discharge current. But on the other hand, it is not that the lower the discharge rate, the better. Some studies have shown that the discharge rate is too small for a long time, and the formation of lead sulfate molecules will increase significantly, resulting in stress that will cause the plate to bend and the active material to fall off, and will also reduce the use of the battery. life.
3.The outside temperature is too high
The rated capacity of the battery refers to the value of the battery at 25°C. It is generally believed that the working temperature of the valve-regulated sealed lead-acid battery is ideal to work within the range of 20-30°C. When the battery temperature is too low, the capacity of the battery is reduced, because the electrolyte cannot fully react with the active material of the plate under low temperature conditions. The reduced capacity will not be able to meet the expected backup time and keep within the prescribed depth of discharge, which will easily cause over-discharge of the battery. Judging from the external parameters of the battery, the voltage has a great relationship with the temperature. For every 1°C increase in temperature, the voltage of a single cell will drop by 3mV. That is to say, the voltage of the lead-acid battery has a negative temperature coefficient, which is -3mV/°C. By the same token, an increase in ambient temperature is likely to cause over-discharge of the battery. The high temperature will also cause the battery to lose water and thermal runaway. Temperature is a major factor affecting the normal operation of the battery. In solar photovoltaic systems, the controller is generally required to have a temperature compensation function.
The above is an introduction to the reasons for the shortened service life of the battery. Avoiding the above problems and maintaining the battery well is the correct way to prolong the service life. Friends can use some repair methods to extend the life of the battery. For example, injecting some electrolyte regularly can reactivate the ion activity and restore its capacity. You can also use professional battery maintenance tools.