The life span of a battery depends on its type. As a rule, 6V and 12V batteries (up to 35Ah) are designed to last up to 5 years. Larger batteries have a maximum life expectancy. To determine the service life of a battery, it is submitted to a series of charge and discharge cycles in certified organizations to validate its performance. However, UPS battery life does not always correspond to its expected durability and this is because the responsible for managing the UPS do not meet all the requirements demanded by the manufacturer.
Temperature is the main cause of premature battery failure. Batteries are designed to work properly at a certain temperature, however, they are often subject to inadequate thermal values. When this happens, chemical reactions are accelerated inside, leading to a degradation of the plates, loss of water and corrosion processes. Lead-acid batteries are at maximum capacity at a temperature of 20°C to 25°C and it is believed that their service life is reduced by 50% with each increase of 10°C above the recommended temperature. Having a good cooling system, which allows the equipment to be at the ideal temperature, is the first step to increase the battery life.
A very common mistake is to place the batteries very close to each other. This bad practice prevents the battery from dissipating the heat generated during recharging, quickly exhausting its useful life. These components must be installed with a minimum spacing of 10 mm from each other.
The fluctuation voltage to which the battery is permanently subjected in the equipment is another factor that influences its useful life. For 25°C, the fluctuating voltage is normally 13.50V to 13.80V. It is advisable that the voltage set on the charger is 13.65V, that is, the intermediate value. Thus, the battery is operating at an adequate voltage even if there are minimal variations in the temperature of the environment where it is inserted. A voltage below the established minimum causes the battery plates to sulfate. This process occurs when the battery cannot take any more charge, which greatly shortens its useful life. In the opposite direction, voltages above the maximum established value cause overload and premature death.
A UPS failure can damage all the activities of organizations and cause unimaginable losses in the short and long term. Proper maintenance is essential to ensure that everything will work as planned and that you will not be surprised by unexpected failures. In order to maximize battery life, it is essential that maintenance is carried out within the periods indicated by the manufacturer. During UPS maintenance, at battery level, the following points are inspected: fluctuation voltage values, load current, temperature, resistance values and ripple values. Preventive maintenance is often not an organizational practice, so problems are detected too late and there is no longer a solution.