Monday, April 24, 2017


Conventional vs Alternative Battery Types in UPS Applications: How they compare in Compatibility and Performance



by Giovanni Zanei, AC power product marketing director for Emerson Network Power in Europe, Middle East and Africa

Choosing the right battery may not be the highest priority of considerations when it comes to data centre logistics. But making an informed decision to suit your requirements can save plenty of time, money and hassle.

Historically, the most common type of battery has been standard Valve-Regulated Lead-Acid (VRLA) batteries, mainly due to their competitive pricing and ability to be used in several applications.

However, over recent years the cost of alternative solutions for the Uninterruptible Power Supplies (UPS) market, such as lithium-ion batteries, has fallen considerably. As a result, these have become attractive options for the data centre industry.

Lithium-ion batteries are not a new technology; in fact rechargeable batteries have been commercially available and used within smartphones, laptops and tablets, for more than a decade.

However, in the UPS market, lithium-ion batteries have been restricted to very specific installations because of their traditionally high cost of investment.

Now that battery suppliers are seeing decreasing pricing trends, the lithium-ion option is being more widely considered.

Therefore, the growing interest in applying this technology to UPS is not because it is new, but because affordability is increasing.

The reduced total cost of ownership has presented the solution as a more viable investment.

 

The need for more flexible solutions

Lithium-ion batteries bring a series of advancements to data centre applications. Compared to VRLA, these batteries have a much higher energy density, allowing more space for servers.

Lithium-ion also has a longer battery life and a wider temperature range, so companies can save on replacement and cooling costs respectively.

What’s more, lithium-ion has a higher charge rate and a slower self-discharge rate, meaning it recharges faster and maintains a longer shelf life to alternative solutions.

These advantages reflect the attractiveness of lithium-ion for energy and IT companies. As part of Emerson Network Power’s global operations, we already have several UPS installations making use of lithium-ion solutions provided by major battery manufacturers and this is due to the full compatibility offered by our high-power UPS systems.
Key things to consider

battery-testsSo what should a decision maker consider when opting for a lithium-ion solution versus a VRLA one? Firstly, do not over-evaluate the initial high CAPEX. While the initial investment costs are admittedly higher than alternative solutions, the total cost of ownership is lower.

This is due to a five to ten year increase in design life that lithium-ion experiences over other options. As a result, OPEX costs are much lower.

Secondly, think about the specific requirements of your data centre. Lithium-ion has a much higher power density for lower space requirements than lead batteries. The footprint and mass reductions means the technology can accommodate for buildings with multiple floors, and mitigate any space or weight capacity issues.

Moreover, lithium-ion is more compatible with both short and long runtimes. This allows batteries to be more flexible and adaptable to requests that change with time.

Finally, our recommendation to customers is to discuss application requirements and safety concerns thoroughly with suppliers, and ensure proper maintenance is delivered through expert servicing.

Therefore, the longer life expectancy, space occupation, data centre configuration specs, flexibility should all be taken into account when choosing a battery solution.

 

Lithium-ion in action

When considering sectors or applications these types of batteries might benefit most from, key ones that spring to mind are telecoms and renewable energy.

Data centres and IT applications with specific temperature, footprint and battery life expectancy or runtime requirements will also capitalise on the substantial rewards.

To bring this to life, we recently tested the latest models of lithium-ion batteries to evaluate compatibility with our high-power UPS solutions. The tests concluded that the batteries’ performance exceeded the expected runtime at the lower power levels.

A 25 percent time reduction compared to the typical lead-acid recharging time was also measured.

What’s more, the installation benefitted from the extremely compact design features. Compared to traditional VRLA batteries, the lithium-ion setup saw a 72 percent reduction in footprint and a 75 percent reduction in weight considering a 360 kW load supplied for 10 minutes.

Moreover, the UPS’s capability to continuously monitor the charge and discharge levels of the batteries may become useful to the user when applying recommendations from battery suppliers. Indeed, lithium-ion batteries come inherently equipped with a Battery Management Systems which allows to always control each single battery behaviour.

Ultimately, different solutions work for different requirements. At Emerson Network Power, we take care of the standard applications as much as we explore newer, alternative technologies, and this is crucial to the flexibility and development of our offerings.
Flexibility is key

All this considered, when it comes to choosing the right type of battery for a UPS system, there is no “one size fits all” policy. The most desirable option will depend on the customer. While there are clear advantages of lithium-ion batteries, traditional technology will not become obsolete in the short term, thus we will continue to offer a wide range of UPS systems compatible with both standard and alternative battery solutions.

A common predication in the industry is that with time, the cost difference between the various options will reduce even further. Customers won’t stop buying conventional options, but more businesses may start seeing the long term benefits of lithium-ion, especially as application in renewable energy industries is increasing more and more.

The prevailing consensus has been that lithium-ion batteries in the UPS market are an expensive solution. While this may be still valid today,  based on battery manufacturers’ data it seems that in the long run it isn’t true anymore as, although lead batteries are relatively low cost, they do not compare to the longer life expectancy and performance of lithium-ion ones.

Thus, a clear economic consideration should be made in favour of lithium-ion because it presents a lower total cost of ownership in the long run. The high CAPEX cost is now starting to see a decreasing trend, and the long term benefits are starting to show their colours.

This re-evaluation therefore presents lithium-ion as a more affordable and viable option for investment in the data centre industry.

Making a decision about the right type of battery for different UPS applications can be a difficult one. While it may not sit as a high priority, the related benefits may become strategic differentiators in an increasingly competitive marketplace.