While lithium-ion (Li-ion) batteries have been used commercially for more than 20 years in various applications, they typically haven’t been adopted as batteries for static data centre UPSs. This was mainly because Li-ion cells that provided UPS vendors with the right balance between price, energy density, power, safety, and reliability for static UPS applications simply weren’t available until this point. However, advancements in Li-ion chemistries and technologies over the last 10 years, as well as a drop in cost, have made Li-ion batteries an increasingly suitable and realistic option.
Li-ion batteries provide significantly more energy and power density in comparison to valve-regulated lead-acid batteries (VRLA), which are the most common type currently used in UPS systems. This means that UPSs built with Li-ion batteries take up far less space in comparison to a VRLA-based solution that delivers the same power. This leads to reduced cooling requirements as well a 60 per cent (approximately) reduction in weight.
Further to this, Li-ion batteries can endure a broader temperature range than VRLA batteries. VRLA battery life is typically reduced by half for every 10°C increase above 25°C ambient temperature. Li-ion batteries are much less sensitive to temperature fluctuations and can withstand spikes in temperature with little effect on battery life.
A third benefit of Li-ion batteries is that they always come with sophisticated battery monitoring systems (BMS) that provide a clear picture of battery runtime and health. This is essentially the same technology that allows you to see how much battery life is left on your smart phone. On the other hand, VRLA batteries rely on technology that makes it difficult to accurately predict when they’re going to fail.
Increased life expectancy is another big benefit of Li-ion batteries. In theory, VRLA batteries used in UPS systems have a life expectancy of 10 years, however due to the limitations around being able to accurately determine their health and life expectancy, most customers replace them after 5 or 6 years. Li-ion batteries of the sort best suited for UPSs are expected to last for more than 10 years.
Like all technology, Li-ion batteries do come with certain challenges. The most noteworthy is the need to find a type of Li-ion battery that’s best suited for UPS applications, rather than an electric car battery, for example. UPS batteries are required to deliver a high volume of power quickly for a short period of time, until the backup generators kick in. Li-ion batteries also cost more up front, however they will last around twice as long.
In summary, Li-ion batteries offer several advantages over traditional valve-regulated, lead acid batteries commonly used in UPSs today. A much longer life span, smaller size and weight, faster recharge times, and declining prices all make Li-ion batteries an appealing energy storage technology.
APC by Schneider Electric have a range of UPS available that use Li-Ion technology. Please contact Computer Merchants for more information.