Telecom equipment usually runs from a -48 V DC supply. A rectifier system converts mains or generator AC power to DC, feeds the equipment, and keeps a battery bank charged. When AC power is lost, the batteries carry the site until power returns or a generator starts. The quality of that handover decides whether a site stays on air.
Rectifier systems
Modern rectifier systems use several plug-in modules in parallel, with enough capacity that the site still runs if one module fails. A controller manages charging, measures load and battery current, and raises alarms. Maintenance should confirm that every module is sharing load, that spare capacity still exists as site load grows, and that alarm outputs actually reach the monitoring centre.
What shortens battery life
Valve-regulated lead-acid (VRLA) batteries are common at telecom sites, and temperature is their biggest enemy. A commonly cited rule of thumb is that VRLA service life roughly halves for every 8 to 10 °C of sustained operation above 25 °C. Incorrect float voltage, frequent deep discharges and poor connections also shorten life. Because the effects build up slowly, a battery bank can look healthy on a voltage reading and still fail to deliver its rated backup time.
Tests that reveal weak batteries early
- Float voltage per block. Large differences between blocks in one string point to cells that are failing.
- Internal resistance or impedance trending. A rising trend against the bank's own baseline is an early warning, even when voltages look normal.
- Connection checks. Loose or corroded terminals create heat and voltage drop, and can be found with torque checks and thermal imaging.
- Capacity discharge testing. A controlled discharge is the only direct proof of how long the bank will actually support the load.
Plan replacements, do not wait for failure
Battery replacement is cheaper and safer when it is planned. Test results, site temperature history and the age of each bank allow replacements to be scheduled and budgeted across a network, with the weakest sites first. Mixing new and old blocks in one string should be avoided, since the weaker blocks limit the whole string.
Low-voltage disconnect and backup time
Low-voltage disconnect settings protect batteries from damaging deep discharge, but they also define how long a site can stay on air during an outage. Settings should be reviewed together with the expected generator start time and the client's availability targets, so that the batteries and the generator work as one system.
BM supplies, installs and maintains battery banks, rectifier systems and UPS installations for telecom operators and infrastructure owners across Saudi Arabia, including kingdom-wide HVAC and DC battery replacement programmes.