The lead-acid battery systems used to power UPS systems have been proven over many years. The Valve Regulated Lead Acid (VRLA) blocks we used three decades ago are the same as those used today! However, in the next few years, Lithium ion (Li-ion) is set to revolutionise how we back-up our power protection systems. How fast the take up will be, will depend on how rapidly prices reduce to levels that make the investment in Li-ion a practical alternative.
Prices are being driving down by the automotive industry and have reduced ten-fold over the past ten years. Perceptions are also changing. In the past, there has been some reticence about small Li-ion applications, however, now with the inclusion of battery monitoring systems they are now regarded as a safe and viable option and are in use in a variety of industries. It is only a matter of time before Li-ion becomes mainstream within datacentres across the world.
Increasingly we are being asked to provide comparative quotes for Lead Acid versus Li-ion batteries for UPS installations. Depending on the customer’s project, we are generally finding the initial cost of buying Li-ion compared with Lead Acid batteries works out at around 2.5 times more expensive. When prices can be reduced to around 1.8 to twice the initial purchase price of Lead Acid, we believe the various benefits and considerations relating to total cost of ownership (TCO) will start outweighing concerns about the initial investment.
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 twice that and has a built-in battery monitoring system which regulates the charge and measures impedance in real-time. If a fault occurs, the battery monitoring system alerts your UPS maintenance provider, raising awareness of an issue before the block fails. With Lead Acid you only know there is a battery problem when you need to use it and if it doesn’t work then it’s too late!
As well as lasting much longer, Li-ion batteries require less than half the physical space of the equivalent Lead Acid blocks and are less than 25% of the weight. Commonly, above ground-floor installations can require structural strengthening of the building simply to house the required Lead Acid batteries. Logistically, moving many tonnes of equipment in and out of an upstairs comms room, when batteries need replacing, can also present challenges. For data-centres looking to increase their power density within the same foot print Li-ion promises a practical solution.
Switching to Li-ion could also improve the overall efficiency of the comms room. This is because a further advantage of Li-ion is that it can work at a higher temperature, therefore requiring less-expensive cooling, reducing the amount of overall energy consumed. Most IT systems work better at >25ºC and the UPS technology itself can work well up to 40ºC. By contrast: an industry standard estimate is that for every 10 degrees above 20ºC the operating life of a VRLA battery is halved. With growing concerns about reducing the carbon footprints of datacentres, being able to decrease or even remove the electricity requirement for cooling could become an increasingly attractive and important consideration.
However, the up-take and roll-out of Li-ion across the datacentre industry will not happen overnight. Not all systems are Li-ion ready, but they need to be. Manufacturers of UPS equipment need to ensure their technology is compatible and can ‘talk’ to the Li-ion battery monitoring system. Currently CENTIEL and only a handful of other manufactures offer Li-ion ready UPS.
In addition, understandably, the critical power protection industry tends to be particularly risk averse. The early adopters will be the sector’s innovators. Then how rapidly we see Li-ion in mainstream will likely depend on the experience of these first small installations.
Interestingly, the adoption of Li-ion within UPS systems so far has been greater in developing countries in Africa and the Middle East, where the main power grid is less reliable than in the UK and frequent power problems are more commonplace. In these instances, the UPS and battery systems are required to be cycled several times per day. This greater adoption is primarily due to the higher cycling life of Li-ion: typically, 2,500 power-up and down cycles compared with around 300 for VRLA technology.
Over time we believe, there will be an inevitable shift towards Lithium ion batteries as cost reductions, driven by developments in the automotive industry, flow through to the standby power sectors. Incorporating Li-ion will inevitably reduce the size and weight of UPS systems overall and the longer useful working life of Li-ion will mean fewer costly replacements. All of which will benefit customers with reductions in both CAPEX and OPEX and make Li-ion batteries a winning solution for UPS applications requiring compact, innovative protection.
This article was originally feature in Electrical Engineering Magazine
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