Statistically the battery breakdown is the first and main cause for an UPS failure, with a loss of electrical power to the privileged utilities it is destined to.
This means that one of the most critical elements of an UPS performance is the battery. A broken/defective battery in a string is enough to drop the utilities connected to the UPS during a power outage. Batteries matching the same technical specifications may offer very different performance on field. Choosing the wrong battery can have a strong negative impact on the systems reliability or on the UPS autonomy, causing unpleasant effects and unexpected costs due to power outage to privileged utilities.