Schneider Electric gave the channel advice on battery care and the most common reasons why these important instruments begin to fail.
Currently, the most advanced power backup systems remain dependent on the relatively low-tech lead-acid battery. Although they are limited in size, they are capable of generating high surge currents, so they are ideal for starting the generator and providing runtime during a utility failure.
However, this means that battery failure in a UPS system can be as critical as any network malfunction. “It is important that the batteries are kept in optimal condition according to their application. Replacing a battery before it has reached its end of service creates the risk of additional failures and unnecessary costs. For the system to be reliable, batteries must be constantly monitored and managed, ”said Yanina Bonelli, Product Manager Home and Business Networks of Schneider Electric.
On the other hand, a battery provides an electric charge as a result of an electrochemical reaction. However, performance begins to degrade from the moment when the pulp is applied at the factory to its lead networks. Unlike many components in a mechanical system, there may not be an external indication of an impending battery failure (except in the most extreme cases, such as thermal overflow).
While each cell in a battery has its own unique rate of deterioration, there are a variety of factors that contribute to a decrease in its useful life. According to Battery Council International (2010), avoidable problems and manufacturing errors are combined and represent a total of 69% of the failures of a battery.
Main reasons for a failure
The operating temperature has the greatest impact on the premature failure of a battery. Consequently, higher temperatures inside the battery cells cause their chemical reactions to accelerate, increasing current consumption, water loss and the internal corrosion rate in the positive grid material.
For this reason, the corrosion of the network can cause short circuits, due to the compact design of modern batteries. Usually, a battery that fails due to this problem has been in service for longer than its expected lifespan.
On the other hand, sulfation can occur when a battery does not receive a full charge and is common when the battery is used in stop / start applications, where lead dioxide disintegrates in the negative electrode, reducing the active surface area and causing loss of capacity. It also reduces the consequent capacity of the battery to receive a charge; causing a longer load cycle as internal resistance increases.
Similarly, there are short circuits, which as the paste in the positive electrode becomes porous, causes a loss of contact between the positive material and the grid. Gradually, during the pouring of the plates, it can detach from paste and when this detached material comes into contact with the plates, it causes a short circuit in the cell.
Another problem that causes failures in a battery is drying or loss of water. As the battery is used up, it loses water, which leads to eventual drying, loss of capacity and, finally, to the rupture of the separator (insulator). In today’s sealed batteries, loss of water leads to desiccation and decreased capacity.
There are also thermal leaks, which occur when the temperature inside the battery is high enough so that it cannot dissipate from the housing, which causes an increase in the temperature around the outside of the battery. This, in turn, increases the temperature within it, which ultimately leads to the melting of the housing and the exposed battery rack.
Top mossing, another factor that causes failures in a battery and is the result of inaccuracy or carelessness during the manufacturing process, when the separators and the plates are misaligned, which causes the areas of the plate to be exposed. This exposure allows a crystalline “moss” to form, leading to self-discharge or “soft shorts.”
Lead acid batteries remain a cost-effective solution in backup applications, as there are reliable remote management software to help monitor and maintain lead-acid batteries, as well as advice on replacement. With proper management, they can provide years of reliable service to their users.