Are you managing the expected lifespan of your UPS batteries, or do you not care about their lifespan because the equipment is under warranty?
UPS is like an unreliable friend—you think you can trust them, but they can let you down when you least expect it, or even when you need them most.
Data center backup power systems can have several drawbacks: faulty circuit breakers, poor power management, or phase imbalance can lead to overloads or even design and safety issues. Even if everything else is correct, the uninterruptible power supply (UPS) battery can be a weak link.
Before the problem occurred, the batteries appeared to be working perfectly. When a failure occurs and the system suddenly switches to battery power, the load becomes extremely heavy. This puts significant stress on the batteries and can cause them to fail, potentially with devastating consequences for the data center.
UPS battery options
The battery options for UPS have not changed much in recent decades: either wet lead-acid batteries or sealed lead-acid (VRLA) batteries.
Wet cells remain standard equipment in large data centers due to their long reliability. These cells are immersed in large and expensive sulfuric acid tanks, requiring regular monitoring and maintenance. They also require enhanced safety precautions, such as sealing them to separate potentially sulfuric acid-contaminated rooms from the UPS.
VRLA is currently the most advanced UPS standard for data centers. These batteries are sealed in a container with a paste electrolyte and use a different charging system, making them safer and avoiding the need for special facilities to house them. VRLA requires a longer charging time than wet batteries, partly due to the lifespan of UPS batteries. Wet lead-acid batteries can last up to 25 years with proper care, while VRLA batteries need to be replaced after 3 to 5 years.
Extend UPS battery life
Data center managers must take steps to maximize UPS battery life and prevent catastrophic failures.
Each UPS should be configured with at least two battery strings. If one string fails, the second should be able to maintain power—although this may last for less than half the time. UPS battery life is a non-linear function. Two battery strings will last more than twice as long as a single string. At least you won’t encounter a sudden accident.
All UPS systems require two sets of battery strings to prevent catastrophic failure if one set fails.
VRLA batteries typically cause total failure: a single fault can cause the entire battery string to fail, with no indication of which specific battery is faulty. Wet cell battery failures or short circuits will cause a drop in the total voltage of the battery string, but the UPS can still continue to transmit power.