An Uninterruptible Power Supply (UPS) system is only as reliable as the batteries behind it. And when those batteries start to fail, the consequences can be immediate: data loss, hardware damage, non-compliance, and operational shutdown.
Failing UPS batteries are one of the most common causes of power protection failure. But most battery-related issues don’t happen overnight. They develop gradually, often quietly, and almost always avoid detection without proper checks and maintenance.
This guide will help Facilities Managers and IT teams identify early warning signs that a UPS battery replacement may be needed, and explain why regular maintenance by trained UPS engineers is key to preventing disruption.
1. UPS Runtime Has Dropped Unexpectedly
If your UPS system no longer holds charge for as long as it used to, or if runtime varies between tests, it’s often an early sign of battery degradation. This could be caused by sulphation, increased internal resistance, or ageing cells. A reduced runtime means your system may not support critical equipment during an outage, putting uptime at risk. Planning for a UPS battery replacement at this stage avoids disruption later.
2. Repeated Battery Alarms or Self-Test Failures
Frequent alarms or failed battery self-tests suggest the UPS system is detecting irregularities in charge, discharge, or overall battery condition. These alerts can often be overlooked, especially if the system is still operational. But they’re early warnings that shouldn’t be ignored. If problems persist, the likelihood of failure under load increases significantly.
3. Battery Age Is Unknown or Exceeds 3–5 Years
Most sealed lead-acid batteries have a life of 3 to 5 years. After that, reliability begins to decline, even if the batteries appear intact. If the installation date is unclear or if the batteries have already exceeded their service life, there’s a higher chance of failure without warning. In these cases, scheduling a UPS battery replacement before issues arise is a safer approach.
4. Uneven Voltages Across Battery Strings
Voltage imbalances between batteries in the same string indicate that one or more cells are underperforming. This puts additional strain on the remaining batteries and leads to faster degradation across the system. Without proper testing, this issue can go unnoticed until backup time is compromised or runtime is drastically reduced.
5. The UPS Hasn’t Been Properly Inspected in Over a Year
Many battery failures are entirely preventable with regular maintenance. If your UPS hasn’t been assessed in the past 12 months, there’s a risk that early signs like swelling, loose connections, or falling capacity have gone unnoticed. Annual testing is essential to catch these issues early and plan battery replacements before they become urgent.
Why Scheduled Maintenance is Non-Negotiable
UPS batteries rarely fail without warning. The problem is, those warnings often go unnoticed until it’s too late. Regular maintenance is the only way to catch issues early and keep your system ready when it’s needed most.
Working with engineers who are trained specifically in UPS systems and battery testing ensures:
- Degraded batteries are picked up before they impact runtime
- Compliance with manufacturer guidance and UK regulations is maintained
- Replacements are planned, not reactive
- Service reports are clear, accurate, and audit-ready
General contractors or electricians may tick a box, but most don’t have the tools, training, or experience to run impedance tests, perform load bank analysis, or detect internal UPS battery faults. A quick visual check won’t reveal reduced capacity or hidden wear, and without proper testing, problems go unnoticed until the system fails.
Book a Full UPS Battery Assessment
There are several ways to extend the life of your UPS batteries, but if any of the warning signs above sound familiar, or if your system hasn’t been assessed in the last 12 months, it’s time to take action.
Uninterrupted Power Solutions provides nationwide UPS & Battery Risk Assessments and UPS Battery Replacement Services, delivered by a team that understands the risks and the regulations. Whether you manage a data centre, hospital, public access buildings, or commercial facility, we’ll help you stay protected, compliant, and operational.
Get in touch today to book your UPS battery assessment.