Lithium-Ion UPS vs. Lead-Acid: Reduce Cost and Improve Performance

For years, uninterruptible power supplies (UPSs) have primarily used valve-regulated lead-acid (VRLA) batteries. Lead-acid batteries offered a good mix of price, performance, and safety for data center environments.

Now, however, a newer technology is challenging the dominance of VRLA batteries in UPSs. Lithium-ion batteries are far more efficient and better suited to the demands placed on UPSs in the data center. Although they cost more, lithium-ion batteries represent a smarter choice for data center UPS applications. In a previous article, we dove into the differences between lead-acid vs. lithium batteries. In this blog, we’ll explore the implications of the differences in battery technology as they relate to uninterruptible power supplies below.

Benefits of Lithium-Ion UPSs vs. Lead-Acid

More Compact

Lithium-ion batteries have a very high energy density compared to other battery technologies. A 1kg lithium-ion battery can store 150 watt-hours of electricity — six times as much as a 1kg VRLA battery. Because of the lighter-weight battery, lithium-ion UPSs have a significantly smaller footprint than their VRLA counterparts. That’s extremely valuable where space is at a premium.

Longer Lifecycle

“Cyclic life” refers to the number of charge/discharge cycles in a battery’s useful life. While cyclic life depends upon the depth of discharge, lithium-ion batteries can handle hundreds of charge/discharge cycles. Moreover, they have no memory effect, so they do not have to be fully discharged before recharging. A longer lifecycle means that UPS batteries don’t have to be replaced as frequently.

Faster Charge

Battery recharge times are a key consideration in data center applications where availability is critical. Lithium-ion UPS batteries can be fully charged in about two hours. By contrast, lead-acid UPS batteries require up to 24 hours to recharge.

Greater Depth of Discharge

A battery’s “depth of discharge” is the percentage of the overall capacity drained in a particular cycle. Many manufacturers will specify the maximum recommended depth of discharge for optimal battery performance. Lithium-ion batteries have a depth of discharge of 85 percent or more, which means that the uninterruptible power supply has additional energy available per cycle.

Higher Operating Temperature

The operating temperature of a battery affects its lifespan. Lithium-ion UPSs can operate at up to 105 degrees, while lead-acid UPSs have a recommended operating temperature of 68 to 77 degrees. Lead-acid UPSs must be cooled in the same way as IT equipment, increasing the operational costs of the data center.

Energy Efficiency

“Efficiency” is the ratio of energy retrieved from a battery to the energy supplied to the battery. Most lithium-ion batteries have 95 percent or greater efficiency. A lithium-ion UPS operating at peak capacity can reduce energy losses in the data center compared to older technologies.

Minimal Maintenance

Lithium-ion UPSs require very little maintenance — typically, just an annual torque check. Additionally, IT staff won’t have to change the batteries very frequently. In fact, lithium-ion batteries last up to 10 years, or about as long as the uninterruptible power supply itself. VRLA UPS batteries, in contrast, have to be replaced every three to five years.

Lower Long-Term Costs

The purchase price of the uninterruptible power supply is just one factor in the total cost of ownership. Installation, power and cooling, maintenance, and replacement batteries must also be considered. Over the long term, lithium-ion UPSs are more cost-efficient than lead-acid UPSs.

Empowers Edge Data Centers

Space is often limited in edge data centers, and conditions are less than ideal for IT equipment. There’s typically no onsite IT staff, so the equipment needs to be monitored and managed remotely. When architecting the edge data center infrastructure, organizations must focus on efficiency. That’s why a lithium-ion UPS is the best backup power choice for the edge.

Explore our UPS buying guide for more information on selecting the perfect UPS for your IT environment.

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