Today’s data centers are more complex than ever before, but one thing has remained unchanged over the past three decades – batteries are a critical but imperfect part of the power chain. Data centers have long been at the mercy of decades-old valve-regulated lead acid (VRLA) batteries that get the job done just well enough to keep data center managers up at night.

That’s starting to change. Nearly three decades after they revolutionized consumer electronics by reducing size and weight and increasing battery life, lithium-ion batteries are emerging as a viable alternative to VRLA in the data center. In fact, according to a report on the global data center UPS market from Research and Markets, lithium-ion batteries are expected to account for 35 percent of the market share for UPS batteries by 2025, and that may be overly conservative.

It's growing

Lithium rich piles of salt at Salar de Uyuni, Bolivia
– Wikimedia Commons/Luca Galuzzi

The advantages are obvious. Most significantly:

- Longer life: Lithium-ion batteries can last as much as four times as long as VRLA and routinely last two-to-three times as long. Why does that matter? The most significant cost associated with batteries is replacement. In most cases, VRLA batteries would need to be replaced multiple times before the first replacement of a lithium-ion battery. Of course, as with all batteries, life and replacement claims require documentation to be trusted.

- Reduced cooling costs: There are a number of variables that influence the cooling required for batteries and the associated costs, but some lithium-ion batteries can operate at higher ambient temperatures than VRLA and reduce battery cooling costs by as much as 70 percent.

One important thing to keep in mind: Lithium-ion battery systems are more than just the chemistry used to store and supply energy. A battery management system is integral to protecting the battery from excessive charging or discharging current, low or high voltage extremes and high temperatures. Each cell or group of cells is monitored and continuously controlled without requiring action from data center managers. Additionally, the battery operating data is available for export to other monitoring systems without any incremental cost.

There are complexities that don’t exist with VRLA, but today’s battery management systems and integrated battery storage solutions simplify lithium-ion deployment.

John B. Goodenough

The restless inventor

The father of the lithium-ion battery believes he has invented a worthy successor. Others aren't so sure.

This is important as the industry adjusts to evolving fire codes for deployment of lithium-ion batteries. These codes – NFPA1 and IFC 2018 – are gradually being adopted right now and are likely to introduce new variables into the decision-making process around UPS batteries.

These new fire codes specify a minimum spacing between lithium-ion battery cabinets unless the manufacturer can show that any fire in one cabinet won’t spread to others in a system. Unfortunately, this fire testing requirement doesn’t yet have any pass/fail criteria. In the interim, it may be necessary to share the fire test results directly with local fire marshals to gain their agreement with the deployment plan – a step responsible vendors will be prepared to take.

While a pass/fail test and approval mechanism would alleviate uncertainty, any efforts designed to ensure a safer workplace should be applauded. This step is not unlike what happened in the automotive industry, which was an early adopter of lithium-ion batteries. Once the industry established safety requirements for those batteries, manufacturers engineered products to meet those requirements. The same will happen in data centers.

The key for data center managers is to engage with lithium-ion suppliers that have the expertise and wherewithal to conduct the required tests and ensure the safety of their solutions. Suppliers will adjust to these fire codes and the industry will be safer for the effort, but some lithium-ion manufacturers will lead the charge on safety and others will follow. Identify the leaders and work with them.

Beyond evolving safety standards, initial costs tend to be the primary deterrent to lithium-ion adoption. The up-front cost of lithium-ion batteries is higher than VRLA – roughly 1.75x, on average – but that gap is shrinking by the day. Organizations with the flexibility to take a longer view and consider TCO can find lithium-ion a tremendous value. When considering the bigger picture, including not just up-front costs, but the cost of installation, delayed replacement and maintenance costs, reduced cooling costs and, perhaps most importantly, the appeal of avoiding the seemingly endless cycle of VRLA replacement, the cost comparison actually favors lithium-ion.

Keep in mind, there are many different types of lithium-ion batteries and chemistries – lithium iron phosphate (LFP), lithium-ion manganese oxide (LMO), and lithium nickel manganese cobalt oxide (NMC) to name just a few. LFP and LMO/NMC are the preferred options in the data center, each having advantages based on the desired operating time. Many of the lithium-ion batteries used in today’s data centers have been used and vetted in electric and hybrid automobiles.

Data center managers are, historically, conservative by nature – with good reason when your livelihood depends on reliability – but more and more organizations are embracing innovation as they work to reduce costs and meet the new demands placed on today’s networks.

Lithium-ion batteries are not just a viable alternative to VRLA; in many cases, they are becoming the preferred option. When the benefits are so clearly defined – and with operating experience growing – it’s likely that lithium-ion will continue to gain market share in the data center UPS space.