Photo of an Eaton VRLA Battery
Energy Storage Options


Though an uninterruptible power supply (UPS) performs many important functions, most users value them chiefly for the emergency energy they provide during a power outage.

UPSs give IT personnel the time they need to protect sensitive equipment and data from the effects of an electrical service interruption by starting a backup generator, shutting down systems in an orderly fashion, or moving data and processing to a disaster recovery site.

Today, most UPS products use lead acid batteries to store emergency standby power. A proven technology with many decades of successful service in a variety of industrial settings, the lead acid battery is usually the most cost-effective energy storage solution as measured by dollars per minute of backup time.

Traditional choice: Lead acid

Lead acid batteries are hardly a cutting-edge technology. In fact, the first one was invented some 150 years ago. Yet they remain the standby energy storage solution of choice in UPS products today, and with good reason: No other mainstream technology handles the unique demands of the data center as effectively or affordably.


  • Internal chemistry: Lead acid batteries are an almost ideal fit for the unpredictable and inconsistent IT environment, as their internal chemistry enables them to provide high amounts of current on short notice, yet still provide a reasonable service life in float or idle mode.
  • Backup time: Lead acid batteries deliver relatively high amounts of backup time—typically five to 15 minutes.
  • Price: Lead acid batteries are available at a relatively low price, making them the most cost-effective standby power storage solution currently available but now that is changing rapidly, as other technologies have ‘caught up’ in affordability. Competitively priced alternatives exist today.

Alternative: Lithium-ion

Most cell phones and laptops use lithium-ion batteries, which have grown steadily smaller, lighter and denser over the last decade. In industrial settings or data centers, lithium-ion batteries are capable of performing the same functions as lead acid batteries, while offering significant additional benefits.


  • Compact form factor: The best lithium-ion batteries currently available deliver a 60 percent weight saving and 40 percent footprint saving over lead acid batteries.
  • Improved backup time: The batteries are not only much lighter and smaller, but also improve backup time by 30 percent.
  • Long lifespan: Lithium-ion batteries feature a 10-year service life and a much higher cycle life, which will save you money in the longrun. This makes them ideal for grid-sharing applications, being considered by some data center operators.
  • Battery monitoring system: Leading lithium-ion batteries have a built-in battery management system to provide automatic balancing, optimization, and protection for temperature, voltage levels and current concerns.