Data centers, hospitals, manufacturing facilities, and countless other businesses across eastern and central Arkansas depend on uninterruptible power supply (UPS) systems to bridge the gap between utility power loss and generator startup—or to ride through brief power disturbances without any interruption at all. Unlike generators that take seconds or even minutes to start and stabilize, UPS systems respond instantaneously, drawing on battery reserves to maintain power to critical loads without missing a beat. For operations where even a momentary power loss could corrupt data, damage equipment, or disrupt sensitive processes, UPS systems represent the first and most critical line of defense against power quality problems.
The challenge with UPS systems lies in their dependency on batteries—electrochemical devices with finite service lives that deteriorate whether used or not. A UPS system that appears to function perfectly during utility power availability may fail to support loads when actually needed if its batteries have degraded beyond usefulness. The NFPA 70B standard addresses this challenge by establishing comprehensive maintenance and testing practices designed to ensure UPS systems will perform reliably when called upon, providing the protection your business depends on.
Battery Capacity and Impedance Testing: Measuring What Matters
The most fundamental question about any UPS battery system is whether it can actually deliver the required power for the required duration during an outage. Battery capacity and impedance testing answers this question by measuring the actual performance capabilities of battery strings or individual cells. NFPA 70B recommends this testing be performed annually for the first few years of battery life, then every 3-5 years as batteries age, with more frequent testing as batteries approach the end of their expected service life.
Battery capacity testing involves discharging the battery string at a controlled rate while monitoring voltage, current, and time to determine the actual amp-hour capacity available. This test reveals whether batteries can still deliver their rated capacity or have degraded to the point where runtime will be shorter than expected. For businesses relying on specific backup times—perhaps waiting for generator startup or completing orderly system shutdowns—knowing actual battery capacity is essential for ensuring adequate protection.
Impedance or conductance testing provides an alternative or complementary approach to capacity testing. These tests measure the internal resistance of battery cells, which increases as batteries age and deteriorate. High impedance indicates reduced ability to deliver current, correlating with reduced capacity and increased risk of failure. Impedance testing can often be performed more quickly than full discharge capacity testing, making it practical for more frequent monitoring of battery condition.
The testing frequency should increase as batteries age, as deterioration typically accelerates in the later years of service life. A battery string that tested perfectly at three years old might show significant degradation by year seven or eight, making regular testing essential for identifying when replacement is needed before batteries fail during actual service.
UPS Functional Transfer Tests: Proving System Response
Having good batteries is only part of the equation—the UPS system itself must detect utility power problems and transfer to battery operation seamlessly. Annual functional transfer testing simulates utility power loss to verify that the UPS responds correctly, switches to battery power smoothly, and maintains proper output voltage and frequency to connected loads throughout the transfer and during battery operation.
This testing identifies problems with utility sensing circuits, transfer mechanisms, inverter operation, and control systems that might prevent the UPS from responding correctly during actual power disturbances. Many UPS failures occur not because of battery problems but because of electronic control system issues, aging capacitors, or other component failures that prevent proper system operation. Regular functional testing catches these problems before they compromise system reliability.
The test also verifies that connected loads operate correctly when powered by the UPS inverter rather than utility power. Some equipment sensitive to power quality or harmonic distortion may experience issues when running on UPS power that don’t appear during normal utility operation. Discovering these compatibility issues during testing rather than during actual emergencies allows time to address problems through UPS settings adjustments, power conditioning, or equipment modifications.
For facilities with multiple UPS systems or complex power distribution architectures, functional testing should verify proper coordination between UPS units and confirm that redundant systems provide the intended level of protection. N+1 or 2N redundant UPS configurations only provide their intended protection if all units function correctly and coordinate properly.
Charger Output and Float Current: Keeping Batteries Ready
UPS battery chargers perform the critical function of maintaining batteries at full charge and ready to support loads when needed. Annual testing of charger output voltage, current, and float current ensures chargers function correctly and maintain batteries in optimal condition. Improper charging—whether too high or too low—accelerates battery aging and can lead to premature failure.
Float voltage represents the continuous voltage applied to batteries to maintain full charge without overcharging. This voltage must be precisely controlled within narrow limits specified by battery manufacturers. Too high, and batteries experience accelerated water loss, grid corrosion, and shortened life. Too low, and batteries gradually discharge, sulfate, and lose capacity. Regular measurement and verification of float voltage ensures batteries receive proper care.
Charger output current testing verifies that chargers can deliver sufficient current to recharge depleted batteries after utility outages and maintain float charge on healthy batteries. Undersized or failing chargers may struggle to recharge batteries adequately, leaving systems vulnerable if multiple power disturbances occur in short succession. This becomes particularly important in Arkansas during severe weather seasons when multiple outages might occur over hours or days.
Float current measurement on individual battery strings can identify problems such as shorted cells or strings with excessive self-discharge. Abnormally high float current indicates batteries requiring excessive charging current to maintain voltage, suggesting deterioration or developing faults that warrant investigation and possible replacement.
Capacitor Banks: The Often-Forgotten Component
Many facilities use power factor correction capacitor banks to improve electrical efficiency and reduce utility costs. While not part of UPS systems themselves, these capacitors require maintenance attention similar to batteries—they’re electrochemical devices with finite service lives that deteriorate over time. NFPA 70B recommends annual to 3-5 year testing of capacitor equivalent series resistance (ESR) or impedance to identify deteriorated units before they fail.
Capacitor testing measures the impedance or ESR of capacitor units, which increases as capacitors age and their dielectric materials deteriorate. High ESR indicates reduced capacitance and increased power losses, while extremely high values suggest capacitors nearing failure. Failed capacitor units can cause harmonic problems, reduce power factor correction effectiveness, and potentially damage other electrical equipment if they fail catastrophically.
The testing is typically performed during scheduled maintenance outages when capacitor banks can be safely de-energized and isolated. Individual capacitor elements within banks are tested to identify which specific units require replacement, allowing selective replacement of failed components rather than replacing entire banks unnecessarily.
For facilities using capacitor banks for power factor correction, maintaining these systems properly ensures continued efficiency benefits and avoids potential power quality problems from deteriorated or failed capacitors. The testing intervals align well with other electrical maintenance activities, allowing coordinated maintenance that minimizes outage frequency.
The Arkansas Climate Factor
Operating UPS systems and batteries in Arkansas’s climate presents specific challenges that affect maintenance requirements and battery life. High temperatures accelerate battery aging—as a general rule, battery life decreases by roughly 50% for every 15°F increase in operating temperature above 77°F. Arkansas’s hot summers can significantly shorten battery life in UPS installations without adequate cooling.
UPS rooms and battery cabinets require effective temperature control to maximize battery life and ensure reliable performance. Many facilities underestimate the cooling requirements for UPS installations, particularly as heat loads increase when adding equipment to existing spaces. Regular monitoring of UPS room temperatures and battery cabinet internal temperatures helps identify cooling deficiencies before they significantly impact battery life.
Humidity control also matters for battery systems, particularly in facilities without climate control. High humidity can promote corrosion of terminals and connections, while very low humidity can contribute to static electricity issues. Maintaining UPS installations in climate-controlled environments provides the best protection for both electronic components and battery systems.
Severe weather common in Arkansas—thunderstorms, tornadoes, and occasional ice storms—creates the conditions that most frequently require UPS operation. This makes pre-season maintenance particularly valuable, ensuring UPS systems are ready before severe weather season arrives. Spring maintenance preparations help ensure systems are ready for summer storm season, while fall maintenance prepares for potential winter weather events.
Planning for Battery Replacement
Even with perfect maintenance, batteries have finite service lives—typically 5-10 years depending on type, operating conditions, and usage patterns. Planning and budgeting for eventual battery replacement should be part of any comprehensive UPS maintenance program. Understanding battery condition through regular testing helps predict when replacement will be needed, allowing proactive replacement during planned maintenance rather than emergency replacement after failure.
Battery replacement represents a significant investment, particularly for large UPS installations with extensive battery strings. However, the cost of battery replacement pales compared to the potential cost of UPS failure during a critical power outage. For businesses where power interruption could cause data loss, equipment damage, or process disruption, viewing battery replacement as insurance rather than expense helps maintain appropriate perspective on this necessary investment.
Technology improvements in battery chemistry and construction continue to advance, with newer battery types offering potential advantages in life span, space requirements, or environmental factors. When replacement time arrives, evaluating alternative battery technologies may provide opportunities for improved performance or reduced total cost of ownership compared to simply replacing existing batteries with identical units.
Documentation and Trending
Maintaining comprehensive records of all UPS maintenance activities, test results, and battery performance data creates valuable information for optimizing maintenance programs and predicting future service needs. Tracking battery impedance or capacity measurements over time reveals deterioration trends that help predict remaining useful life and plan replacement timing. This historical data proves particularly valuable for facilities with multiple UPS systems, allowing comparison of battery performance across different installations and identifying factors that affect battery longevity.
Documentation should include not just test results but also environmental conditions, utility power quality events, and any unusual occurrences that might affect UPS or battery condition. Understanding the full context of equipment operation helps interpret test results and identify factors contributing to equipment aging or performance changes. Modern UPS systems often include data logging capabilities that automatically record operating parameters, providing detailed information about system operation and power quality events.
The Bottom Line on UPS Reliability
For Arkansas businesses depending on UPS systems to protect critical operations from power disturbances, systematic maintenance based on NFPA 70B standards represents essential protection for your protection system. The combination of battery testing, functional verification, charger performance monitoring, and environmental control ensures that your UPS will perform reliably when utility power fails, providing the seamless power continuity your business operations demand.
This blog post was created by Ag Electric Services, LLC, an Arkansas based electrical and general contractor serving the following areas of Central and Eastern Arkansas: McCrory, Augusta, Newport, Wynne, Brinkley, Des Arc, Forrest City, Hickory Ridge, Cherry Valley, Tuckerman, Jonesboro, Searcy, Pangburn, Heber Springs, Greers Ferry, Rosebud, Quitman, Romance, Kensett, Georgetown, Cabot, Beebe, El Paso, Hickory Plains, Carlisle, Lonoke, Little Rock, North Little Rock, Sherwood, Jacksonville, Maumelle, Conway, Mayflower, Vilonia. If you would like more information about the services we provide, please click “Services” in the main menu, or contact us through the online information request form on the “Contact Us” page.