Why This Matters on Your Plant Floor
An industrial UPS failure costs far more than the replacement unit. Unplanned downtime halts production lines, ruins batches in process and loses revenue per minute. A failed UPS inspection leaves you exposed: you cannot prove to your insurer or your customer that you maintained equipment to standard. A maintenance checklist, carried out between authorised service visits, catches battery degradation, room hazards and electrical drift before they fail.
Preventive maintenance does not add years to a battery's design life, which is typically three to five years for standard VRLA blocks at 25°C and longer for long-life types. It helps the battery reach that life instead of failing early in hot plant conditions. It identifies weak cells, loose terminals and environmental hazards. It documents compliance with electrical standards and your duty of care to site safety. On the plant floor, a checklist is your early warning system.
Monthly Visual Inspection and Safety Checks
Every month, inspect the UPS cabinet and battery room without tools. Look for damage, corrosion, loose fixings and signs of heat or fluid leaks. Check that all cabinet doors shut and latch. Confirm that ventilation grilles are clear and cooling fans are running without noise or vibration.
In the battery room, check for odours, visible corrosion on terminals, white acid mist on connectors or pooled fluid under racks. Loose or dirty battery connections cause heat buildup at terminals, reducing system capacity, lowering lifespan and increasing fire hazard risk. If corrosion is light, record and photograph it for your authorised service centre. Lead-acid terminal corrosion is acidic and is cleaned with a weak sodium bicarbonate (baking soda) solution, never an acid. Call your authorised service centre if corrosion is heavy or terminals are loose.
Check that all alarm indicators on the front panel are working. Press test buttons to confirm that audio and visual alarms sound and light. If the UPS has a separate battery room, check that the door is closed and that access is restricted to authorised personnel. Confirm that hydrogen gas detectors (where fitted) show green status. Hydrogen detectors should be installed near ceilings and above battery racks, as hydrogen gas rises quickly.
Record all findings on a checklist form. Photograph any corrosion or damage. If you find loose terminals, visible gas leaks, or alarm failures, contact your authorised service centre immediately. Do not attempt to tighten terminals or replace alarms yourself.
Quarterly Electrical Measurements and Load Assessment
Every three months, measure the DC output voltage, float current, AC ripple and load percentage with a calibrated multimeter or power analyser. Only qualified maintenance personnel must perform these measurements; improper testing can damage the system.
Measure the DC bus voltage with the UPS on mains supply and no load. For a VRLA battery bank, float voltage should be 2.25–2.30 volts per cell (VPC) at 25°C ambient temperature. Float voltage should stay within the battery maker's tolerance of its datasheet value, typically plus or minus 0.02 V per cell (about 0.1 V on a 12 V block). A larger drift points to charger calibration drift or a failing cell and needs your authorised service centre. Rising float current against constant charger voltage, paired with rising cell temperatures, is the earliest warning sign of VRLA thermal runaway. If float voltage or float current drifts, call your service centre for charger recalibration or battery replacement.
| Parameter | Quarterly Check | Alert Threshold | Action |
|---|---|---|---|
| Float voltage (VRLA) | 2.25–2.30 VPC at 25°C | Drift >0.02 VPC (about 0.1 V on a 12 V block) from datasheet value | Charger calibration or cell replacement |
| AC ripple on DC output | <1% RMS | >1% RMS | Filter inspection or mains quality check |
| Load utilisation | Check kVA or kW as % | 40–80% optimal; >80% reduces efficiency | Right-size load or upgrade capacity |
| Minimum DC voltage under load | Do not drop below 1.75 VPC | <1.75 VPC indicates over-discharge | Audit battery capacity and load time |
| Recharge time to 95% capacity | Should reach 95% within 24 hours | Recharge time >24 hours | Cell or charger issues; seek service |
Measure AC ripple on the DC output bus with the UPS rectifier supplying the load. AC ripple should be less than 1% RMS; excessive ripple accelerates battery degradation and can trip electronic loads. If ripple exceeds 1%, check mains quality first; if mains is clean, contact your service centre for rectifier or filter inspection.
Record the total kVA or kW load drawn from the UPS and calculate load as a percentage of rated capacity. UPS load utilisation between 40–80% of capacity typically provides optimal efficiency and battery life. If load exceeds 80%, your battery discharge time is shortened and thermal stress increases. If load is below 40%, you are underusing capacity. Neither is ideal; review your load forecast and capacity plan.
Perform a brief discharge test by switching the UPS to battery mode for two to five minutes under normal load. Observe that DC voltage does not drop below 1.75 VPC under load. If voltage sags below this threshold, it indicates over-discharge risk and suggests battery capacity has faded. Do not run the test if load would be lost; if uncertainty exists, call your service centre to schedule a safe discharge test.
Semi-Annual Battery Capacity Testing and Cell Inspection
Every six months, perform a full-load or half-load battery discharge test to measure remaining capacity. Only certified UPS technicians must perform load testing; improper testing can damage cells and connected equipment.
Capacity testing works as follows. Under controlled load, the UPS runs on battery alone. Discharge time is measured from 100% state of charge to the minimum DC voltage threshold (usually 1.75 VPC). The measured time is then compared to the rated discharge time at the same load percentage. For example, if the runtime table for a 20 kVA online UPS gives 15 minutes at 100% load, the healthy figure at 50% load is the table's own 50% value. That is normally more than double, not a simple 2 x 15 = 30 minutes. Compare the measured time with that table value.
Battery capacity should be tested semi-annually, with replacement recommended when capacity drops below 80% of rated capacity. A measured runtime below 80% of the expected runtime at the same load means the battery has reached its replacement point. For example, if the battery maker's runtime table gives 35 minutes at 50% load, a measured runtime under 28 minutes (0.8 x 35 = 28) calls for replacement. Do not wait for the battery to fail; plan replacement during a scheduled maintenance window.
During testing, observe whether all cells reach end voltage at the same time. Battery cells reaching end voltage significantly before others during discharge testing indicate weak cells requiring replacement. If the UPS has a parallel string of batteries, capacity imbalance between strings is a sign of cell failure in the weaker string.
After testing, record the discharge time, final voltage, any cells that lagged, and the calculated capacity as a percentage of rated. If capacity is below 80%, or if any cell shows early end voltage, send a report to your authorised service centre with a request for battery replacement. Recharge the battery straight after the test; the UPS charger does this once it is back on mains. A lead-acid battery left discharged sulphates and leaves the load without backup. Send the test report to your authorised service centre while the battery recharges.
Environmental Monitoring: Temperature and Humidity
Battery room temperature and humidity directly affect UPS lifespan. Check the room thermometer and hygrometer during each quarterly visit. Battery room temperature should be maintained between 20–25°C. Temperatures above 25°C accelerate aging; every 10°C increase halves battery life. In south Gujarat, Daman and the Mumbai belt, where ambient temperatures often exceed 30°C, forced air cooling or air conditioning is essential.
Humidity levels in battery rooms should remain below 60%. High humidity promotes corrosion on terminals, busses and cell casings, and allows salt spray and dust to settle. Install a dehumidifier or increase ventilation if humidity exceeds 60%.
Hydrogen gas accumulation is a critical safety hazard. Flooded cell batteries release hydrogen continuously during charging. VRLA batteries recombine most of their gas but still vent a small amount during normal float charging, and much more when overheated or overcharged. Ventilation systems must keep hydrogen gas concentration below 1% of room air volume. Install a hydrogen detector if you have a lead-acid battery room. Detectors should be positioned near the ceiling and above battery racks, where hydrogen rises and collects. If a detector triggers an alarm, evacuate the room immediately, do not use electrical switches or phones, and call emergency services.
Record temperature and humidity on a log sheet. If temperature trends upward, review cooling capacity or check whether the room is poorly insulated or has direct sunlight exposure. If humidity remains high despite ventilation, increase fan speed or schedule a dehumidifier service.
Alarm Function and Monitoring System Checks
Check that the UPS alarm and monitoring system responds correctly to faults. Press the alarm test button monthly to confirm that the audible alarm sounds and that the visual indicators light. If the UPS has an RS-232, Ethernet or SNMP connection to a building management system, verify that status messages are being logged correctly. If remote monitoring is disabled, confirm that the alarm relay on the rear panel triggers as expected during a low-battery or over-temperature event.
If the UPS has a separate battery box or remote cabinet, ensure that all signal cables between the UPS and battery monitor are secure and undamaged. A loose connector can cause false low-battery alarms or delay genuine fault alerts.
Review the alarm log every quarter. Repeated low-battery alarms indicate that the power outage duration exceeds the battery runtime you have planned. Review your mains supply interruption history and consider upgrading battery capacity or runtime if interruptions are frequent. Repeated over-temperature alarms indicate that the room is too warm or the UPS load is too high; take action to reduce room temperature or review load balance.
Standards and Compliance
Maintenance procedures for industrial UPS systems align with international practice. Refer to the current edition of IEC 62040 and confirm with your licensed electrical contractor on site-specific requirements.
What We Stock for Your UPS Fleet
Fuji Electric online UPS systems, including the Falcon 8500, are designed for continuous operation at 40°C ambient temperature with special attention to component selection for harsh Indian conditions. Fuji Electric UPS units ship with detailed maintenance checklists and technical bulletins specific to battery type, charger settings and alarm configuration.
If you operate Fuji Electric or other branded UPS systems on an industrial site, we are here to support you. As an authorised channel partner, Vimal Electric Corporation supplies Fuji Electric Falcon 8500 UPS systems. Replacement batteries, spare modules and all repair or service work come through Fuji Electric's authorised service network, and we can put you in touch with it. Whether you need to right-size a load or plan a multi-year fleet maintenance schedule, we can provide guidance based on your site load list and single-line diagram.
Send us an enquiry with your UPS model numbers and maintenance questions. We will put you in touch with the brand's authorised service network, which handles spare parts, repair and service. You can also use our UPS size calculator to confirm that your current system is right-sized for your load profile.