UPS Monitoring: Battery, Load and Runtime

Why Is UPS Monitoring Critical?

An uninterruptible power supply (UPS) is a critical infrastructure component for data centers, hospitals and factories. However, a UPS battery loses its capacity over time — often without anyone noticing. Without proactive UPS monitoring, the following risks become reality:

• When the grid goes down, the UPS shuts off earlier than expected: data loss, production stoppage
• The battery drains completely: premature battery death, high replacement cost
• Critical overload: a load exceeding the UPS capacity is connected and it switches to bypass
• High ambient temperature: halves battery life (50% life loss for every 8°C)

UPS Monitoring Protocols

Modern UPS units can be monitored remotely using two main protocols:

• SNMP (Simple Network Management Protocol): Over Ethernet. Enabled by adding a network management card (NMC) to the UPS. Supported by APC SmartUPS, Eaton 9PX and Socomec Masterys. The OIDs to be monitored are defined via a MIB file.
• Modbus TCP/RTU: Some UPS models support Modbus over RS-485 or Ethernet. Socomec, Riello and Legrand models favor this method.

Monitored UPS Parameters

• Input voltage: Grid voltage quality, undervoltage/overvoltage alarms
• Output voltage and frequency: Quality of the power delivered to the load
• Battery charge percentage (%): How many minutes will it run if the grid fails?
• Estimated runtime (minutes): Battery life under the current load
• Load percentage (%): How much of the UPS capacity is being used?
• UPS mode: Online / Bypass / Battery / ECO mode
• Battery temperature: Early warning for high temperature
• Transfer count: Battery transfers increase battery fatigue

UPS Monitoring with Argus EMS

Argus EMS monitors UPS devices on the same platform as energy analyzers and generators. The entire critical power chain — grid input, UPS, generator and critical load — is visible on a single dashboard.

Alarm rules are configured as follows:

• When battery charge drops below 20%: Critical email alert
• When the UPS switches to bypass mode: Instant notification
• When estimated runtime drops below 5 minutes: Urgent alarm
• When battery temperature rises above 35°C: Warning

Periodic Test Management

UPS units should undergo a full battery test at least twice a year. Argus EMS records battery capacity before and after the test. The capacity-decline graph over the year serves as a reference for battery replacement planning.