1. The impact of the environment
Each VRLA battery is given a corresponding ambient temperature range, and the best performance of the VRLA battery can be exerted when used in this temperature range. Due to the special structure of VRLA battery, its electrolyte concentration is relatively high. When discharging at low temperature and high current density, the negative electrode is easy to form a dense PbSO4 crystal layer, which slows down the chemical reaction speed of the electrode and affects the discharge. On the other hand, if the working environment temperature of the VRLA battery is too high, the oxygen evolution of the positive electrode will accelerate when it exceeds 40°C, and the corrosion rate of the positive electrode will be accelerated. Excessive ambient temperature has a great impact on the service life of VRLA batteries. When the temperature rises, the plate corrosion of the VRLA battery will intensify, and at the same time, more water will be consumed to shorten the life of the VRLA battery.
Excessive ambient temperature is a typical factor affecting the service life of VRLA batteries. Generally, the ambient temperature required by VRLA battery suppliers is 15-20°C. As the temperature rises, the discharge capacity of VRLA batteries also increases, but the ambient temperature Once the temperature exceeds 25°C, as long as the temperature rises by 10°C, the floating charge service life of the VRLA battery will be reduced by half.
2. Long-term floating charge without discharge
At present, most VRLA batteries are in a long-term floating charge state without discharging, but this working state is extremely unreasonable. A large number of operating statistics show that this will cause the anode plate of the VRLA battery to be passivated, the internal resistance of the VRLA battery will increase, and the capacity will decrease, making the actual capacity (Ah) of the VRLA battery lower than its standard capacity, resulting in the VRLA battery. The actual backup power supply time is greatly shortened, reducing the service life of the battery pack. In addition, under long-term floating charging, the voltage difference between single cells increases, resulting in overcharging of batteries with high voltage and undercharging of batteries with low voltage, causing failure of individual batteries in the entire battery pack.
VRLA batteries are low-liquid batteries, and the amount of electrolyte in them is strictly limited, and the amount of electrolyte is filled once before leaving the factory. Once reduced, it is difficult to recover. Therefore, when the moisture in the electrolyte is reduced to a certain extent, it will cause the VRLA battery to fail. In general, the saturation of the electrolyte in the VRLA battery separator should be greater than 95% to work normally. Data show that if 25% of the grid is corroded, the saturation of the VRLA battery diaphragm will be reduced from 95% to 85%, thereby reducing the capacity of the VRLA battery by more than 20%. According to the current industry standard, if the capacity of VRLA battery is reduced by 20%, it means that the working life of VRLA battery has ended.