BATTERY TECHNOLOGY
LEO CRAIG OF RIELLO UPS IRELAND LOOKS AT SOME OF THE ALTERNATIVE BATTERY TECHNOLOGIES THAT CAN BE DEPLOYED WITH UNINTERRUPTIBLE POWER SUPPLIES… Comparing different types of UPS batteries
Leo Craig of Riello UPS Ireland.
Lead acid batteries have long been the proven and preferred method of energy storage with a UPS system. Flooded or vented lead acid (VLA) designs initially dominated the market for years due to their reliability. They came at a high initial cost but provided 12-15 years of service life, although they did require time-consuming maintenance including regular topping up with water. Technology progressed to sealed valve- regulated lead acid (VRLA) batteries that were cheaper and don’t require as much maintenance, although they do have a slightly shorter lifespan. As the name suggests, VRLA batteries are sealed in a case with a valve, which vents to release gas if the internal pressure gets too much. VRLA batteries continue to be the go-to choice for many mission- critical applications due to their track record of reliability and relatively low upfront costs. But they do come with drawbacks too. In particular, they need temperature-controlled conditions to perform at their best. Most VRLA batteries are rated at 20-25°C, with every 10°C increase in temperature reducing their service life by as much as 50%. That’s why facilities such as data centres have to deploy energy-intensive cooling and air conditioning systems. POSSIBILITIES OF PURE LEAD To combat such challenges, many lead acid battery manufacturers are starting to offer high purity lead (>99.9%) alternatives that deliver increased lifespan and wider temperature tolerance. As the name implies, pure lead batteries use freshly-mined, virgin lead not only for the battery grid but also for the positive and negative plates, as well as the active paste that creates the current. This final point means the float charge needed to keep a cell fully charged
is reduced, which also limits the heat generated during charging. This slows the rate of corrosion, extending the overall lifespan of the battery. It also helps make the cells more predictable as they approach their end- of-service life. This means systems can be designed with an autonomy closer to what is truly required, ie a smaller battery that helps to offset what are still higher upfront costs of pure lead than standard VRLA. LOOKING AT LITHIUM-ION Lithium-ion is another potential UPS energy storage technology, driven by its widespread use in the electronics and electric vehicle industries. Li-ion batteries deliver equivalent power density to VRLA in less than half the space. They also have up to 50 times the cycle life and work well in higher temperatures. However, they are still more expensive than lead or pure lead while they also come with significant environmental questions, not to mention the ongoing safety concerns and fire risks.
EVALUATING THE OPTIONS When choosing your UPS batteries, consider the total cost of ownership of all the options. Also take note of the standard warranties offered by manufacturers, as these can differ greatly. Design and service life are also important considerations, but be aware that these can easily be impacted by any changes in how the batteries are used. For further details, Riello UPS Ireland has a white paper titled Comparing Different Types of UPS Batteries, which you can download for free from https://riello.ie/ batteries-whitepaper “When choosing your UPS batteries, consider the total cost of ownership.”
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IRELAND’S ELECTRICAL MAGAZINE | 43
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