Batteries are the most likely to fail component in any UPS installation. In any good high quality UPS the electronics can run for fifteen years; the battery string that keeps them meaningful is designed for three to five, and in real rooms it often achieves far less. The gap between design life and actual life comes down to three things you control: temperature, usage and testing.

The battery is the most likely component to fail in the entire power chain, and the one most often left unmonitored.

Heat is the killer

VRLA battery life is specified at 25 °C. The Arrhenius law (I know it is a very strange name, LOL) that governs the chemistry is unforgiving: for every 10 °C of sustained temperature above that reference, service life roughly get to half. A battery room that drifts to 35 °C through a Jordanian summer turns a 5-year design life into about 2.5 years. Riello’s own technical guidance states the same rule, and recent high-current test data suggests it is if anything optimistic for UPS batteries, which are asked for short, heavy bursts rather than the slow discharge the rule was derived from.

Nothing on the UPS front panel warns you this is happening. The batteries float quietly at the right voltage right up to the day they cannot carry the load. Keep battery spaces at 20 to 25 °C and treat the air conditioning in that room as critical infrastructure, because it is protecting the thing that protects everything else.

The clock starts at the factory

Design life is counted from the production date, not from the day you install. A string that sat in a warehouse for a year arrived having already spent a year of its life. When you receive new batteries, read the date codes. At CET we reject stock that has aged on a shelf, and we tell clients to demand the same of any supplier, because a “new” battery two years off the line is not new in any way that matters.

Load and float discipline

An oversized UPS loafing at 15% load and an overloaded one straining at 95% stress the system in different ways, and both shorten life. We size for operation around 75% of capacity: enough headroom for step loads and growth, enough utilisation to justify the frame you paid for.

Float voltage is the quieter half of the problem. Charger settings that are checked and corrected at every preventive visit keep the string away from the two failure modes at either end — undercharging, which sulfates the plates, and overcharging, which drives grid corrosion and dries the cells out. Both are avoidable, and both are common on sites where nobody checks.

Only a discharge test tells the truth

Impedance readings and panel indicators hint at battery health. A real discharge test proves it, because it does the one thing the float charger never asks the battery to do: deliver its rated capacity under load. Our recommended calendar is a full discharge test at commissioning, every six months through the first two years, and every three months once the string is past its midpoint.

This is exactly the moment most sites discover a weak block — during a controlled test with engineers standing there, rather than during the blackout the whole system exists to survive. The IEEE 1188 threshold is clear: a VRLA string is at end of useful life when it can no longer deliver 80% of rated capacity, and below that the decline steepens fast.

Critical Energy Technologies supplies, installs and tests VRLA, nickel-cadmium and lithium-ion battery systems across Jordan, with maintenance plans that include impedance and discharge testing rather than a visual glance and a signature. If your batteries are more than two years old and have never seen a real discharge test, that is the health check to book before summer, not after it.