New Schneider Electric White Paper Compares Lithium-ion and VRLA Batteries for Data Centre Applications

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Despite their technical characteristics, Lithium-ion batteries have long been considered too expensive for use in backup power supplies for data centres, but decreasing costs driven by the electric car industry make their use increasingly attractive when considering the total cost of ownership over a system’s lifetime.

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Despite the initial cost premium, systems utilising Li-ion battery technology can produce savings of up to 39%, when compared with VRLA batteries.

Developments in Lithium Ion battery technology in recent years, and consequent falls in price, have made them a viable option for use in power backup systems for data centres. Hitherto Valve Regulated Lead Acid (VRLA) batteries were preferred because they offered a better trade off between price, energy density, power, safety, and reliability.

Now, driven by interest in the development of electric cars, Li-ion batteries are becoming available in formats that make their deployment in uninterruptible power supply (UPS) systems used in data centres increasingly attractive.

A White Paper from Schneider Electric, a global specialist in energy management and automation, WP #229 Battery Technology for Data Centers: VRLA vs. Li-ion compares the two technologies from the viewpoint of total cost of ownership (TCO) and highlights the benefits and drawbacks of each option.

The benefits of Li-ion battery technology over VRLA include a much less frequent need to replace batteries over the life of a UPS, thereby reducing the risk of downtime; much lighter batteries for an equivalent amount of energy; up to ten times more discharge cycles depending on chemistry, technology, temperature and depth of discharge; about four times less self-discharge, or slow discharge of a battery while not in use; and four times or more faster charging, a key benefit in multiple outage scenarios.

The main drawback of Li-ion is much greater (perhaps two to three times greater) capital cost for an equivalent amount of energy due to higher manufacturing costs and the need for a battery-management system. There are also stricter transportation regulations, which also add to the cost of deployment.

The White Paper examines the functional differences between power cells, designed to provide a relatively large amount of power in a short amount of time; and energy cells, which are designed to provide a relatively small amount of power over a long period of time. Li-ion batteries can be used as either power cells or energy cells whereas VRLA batteries are used solely as energy cells.

Although some TCO studies for Li-ion batteries have been carried out before, they tend to focus on the requirements of electric vehicles, as that sector is the driver for much Li-ion battery development. The financial analysis in this White Paper is focussed specifically on the requirements of a UPS system for a data centre.

The analysis shows that because of the performance characteristics of Li-ion batteries, systems based on this technology can produce savings of 39% over a ten year period compared with VRLA batteries despite the initial cost premium. Although there are some situations in which the greater capital expenditure will discourage switching over from VRLA batteries in the short term, the likelihood is that Li-ion batteries will fall in price in forthcoming years as new chemistries and technologies come to market. As prices fall, they are likely to become increasingly attractive for data centre operators.

White Paper 229 “Battery Technology for Data Centers: VRLA vs. Li-ion” is available for free download by clicking here.


About the authors
Victor Avelar is the Director and Senior Research Analyst at Schneider Electric’s Data Center Science Center, responsible for data centre design and operations research, and consulting with clients on risk assessment and design practices.

Martin Zacho is a Senior Engineer in Energy Storage Technologies at Schneider Electric, Secure Power, IT Business. He has been involved in all aspects of energy storage technologies since 2008 with special focus on energy storage for large 3-phase UPSs.

About Schneider Electric

Schneider Electric is the global specialist in energy management and automation. With revenues of ~€27 billion in FY2015, our 160,000+ employees serve customers in over 100 countries, helping them to manage their energy and process in ways that are safe, reliable, efficient and sustainable. From the simplest of switches to complex operational systems, our technology, software and services improve the way our customers manage and automate their operations. Our connected technologies reshape industries, transform cities and enrich lives. At Schneider Electric, we call this Life Is On.

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