Advances in Li-ion Battery Technology
These days, the most modern, modular, industry-leading UPS systems can achieve very high levels of availability protecting critical loads in an efficient and reliable way, guaranteeing just milliseconds of downtime per year.
By contrast, we have been using the same traditional Valve Regulated Lead Acid (VRLA) battery blocks for around 30 years to provide a reliable back-up energy source when the main power supply is interrupted. However, they have a number of drawbacks including their size and weight, length of life plus they require expensive cooling to maintain an optimum operating temperature of around 20°C.
We believe the future of UPS battery technology lies in Lithium-ion (Li-ion). Li-ion batteries were first introduced to the consumer market more than 40 years ago, Li-ion is now used in laptops, mobile phones and to power our electric cars.
One disadvantage which has slowed the introduction of Li-ion to the UPS market has been the cost. However, developments in the automotive sector have driven down prices significantly over the past decade. Depending on the project, we are generally finding the initial cost of buying Li-ion compared with Lead Acid batteries works out at around twice as expensive.
However, Li-ion lasts twice as long and so considerations relating to total cost of ownership (TCO) have now started outweighing concerns about the initial investment, particularly when we look at the various additional advantages of Li-ion namely: they are smaller, lighter and operate at higher temperatures.
Length of Life
One of the main benefits of Li-ion is length of life. Lead Acid batteries last around ten years but are normally replaced every seven or eight years. Li-ion lasts around twice this time, in part because of its higher cycling life: typically, 2,500 power-up and down cycles compared with around 300 for VRLA technology.
Li-ion can work at a higher temperature, therefore requires less-expensive cooling, reducing the amount of overall energy consumed and a lower TCO. Most IT systems work better at >25°C and the
UPS technology itself can work well up to 40°C. By contrast: an industry standard estimate is that for every 10 degrees above 20°C the operating life of a VRLA battery is halved.
Size and Weight
Last year, CENTIEL completed a UPS installation in central London. The modern office block was situated on the third floor of the building over a large atrium. Our CumulusPower UPS is small and lightweight and so could be positioned on the normal floor area.
However, because of the required two-hour run time, the 13 tonnes of VLRA batteries had to be situated right above an unsupported roof space. A structural engineer had to design and fabricate special steel girders which bolted to the building’s main pillars, strong enough to support the batteries. This work significantly added to the cost of the installation.
In the future, it is these types of facilities where space is at a premium which will benefit from Li-ion as it is around 25% lighter and smaller than VRLA blocks.
The publicised fire risk of Li-ion technology has also resulted in reluctance of take up. However, any technology which is not managed correctly is hazardous. These days, cars come with warning lights should break fluid become low or if lights fail, plus they are fitted with seat belts and airbags in the event of an emergency. The modern-day Li-ion batteries have also been developed to minimise risk and prevent thermal runaway provided they are managed correctly.
The key point is that Li-ion batteries are more sensitive to how they are charged and discharged and therefore need to be linked to a monitoring and control device. CENTIEL’s Li-ion battery monitoring system collects and reports data in real time. This system provides early warning of any issues and automatically shuts down faulty cells if necessary. Engineers are also forewarned via an alarm and so are made aware of an issue before the block fails. Not all UPS systems are Li-ion ready, but they need to be.
In addition, the more modern Li-ion batteries have been developed with a ‘belt and braces’ approach and can include numerous further safety features such as: steel containers, internal separators that melt at high temperatures to shutdown conductivity, current collects from opposite end of pack ensuring there are no hotspots at high current density areas and improvements to cathode material which is more stable during overcharge.
Every battery including Lead-acid batteries are a potential hazard but managed correctly, Li-ion technology has now been developed to be safe to use in Data Centres and other facilities requiring critical power protection.
At Data Centre World we will be demonstrating the benefits of CENTIEL’s Li-ion solution, which has already started shipping to our most forward-thinking clients looking to capitalise on the advantages of Li-ion.