Why lithium-ion based UPS are ideal for sensitive healthcare applications

Power Control
07 Oct 2020

Lithium-ion has been one of the most talked about developments in the UPS industry this year, revolutionising the way that UPS systems are used. Where they were once only installed to support sensitive loads in the event of a power failure, lithium-ion innovations have meant that UPS systems can diversify into facilitating energy storage, managing peak shaving, and maintaining levels of impedance.

The healthcare industry represents one of the most varied applications for critical power systems. These systems must support intensive care units, diagnostic systems, onsite data centres, life safety systems such as emergency lights, emergency rooms and medical imaging devices. With such an array of demanding applications and design considerations, it is more important than ever to work closely with consultants and facility managers and implement new critical power technologies.

Medical imaging can be one of the most sensitive applications, requiring levels of power at both extremes. Whilst idle, the medical imaging device requires only a small amount of electricity. However, whilst a patient is being scanned, a large amount of electricity is required to power the device for a short amount of time.

It is often the case that the supply of mains power to older hospital infrastructure is too small to support these temporary spikes that advanced medical technology creates, and so alternative sources are required.

By using lithium-ion UPS systems to store energy, more advanced medical technology can be used in existing older hospital buildings. There are a number of benefits to be had by choosing lithium-ion based UPS over the traditional VRLA (valve regulated lead acid) battery. Firstly, by drawing on the battery chemistry’s ability to store large amounts of electricity and the fact that they can be charged/discharged many times in their lifetime a necessary energy storage solution is created to enable peak shaving.

In the energy industry peak shaving refers to the levelling out of peaks in electricity used by energy storage systems. This is most commonly used to take advantage of storing energy during times where electricity from the grid is cheap and using the stored electricity during peak times of the day. However, it also branches into load control whereby the UPS provides shorts burst of additional power above what is available from a mains supply, as and when required.

For example, if the maximum input of a hospital is 100KW, where a lithium-ion UPS is installed, the input supply can be limited to the maximum 100KW and any additional power needed to support the medical imaging device will be drawn from energy stored in the batteries of the UPS system.

In this scenario, the UPS is being used both as an energy storage system and a tertiary supply of power, in line with relevant regulation relating to medical applications and backup power. Power failure or spikes could disrupt the medical imaging process and put patients at risk.

Whilst using a typical VRLA based UPS for this application is possible, a larger quantity of batteries would be required to provide the same amount of storage capability, requiring more space, and making the solution up to 5x heavier.

Secondly, a lithium-ion battery has a higher depth of discharge. This refers to the amount of overall capacity that can be used before recharging the battery, every battery chemistry has a recommended level. A VRLA battery should not be discharged past 50%, whereas a lithium-ion can handle a depth of 80% or more. This means that when using the UPS as an energy storage device, more energy can be utilised before charging is required and fewer batteries are necessary to achieve the same output power.

In addition to this, the charge rate of lithium-ion is faster than that of VRLA. Lead acid batteries are limited in how much charge current they can handle, mainly because they would overheat, whereas lithium-ion can handle a higher amperage from the charger. In some cases, the batteries can charge up to 2x more quickly, making them the ideal battery for applications that require constant use.

Another benefit to healthcare applications is the number of cycles (number of times a battery can be charged and discharged before the battery starts to degrade) a lithium-ion battery can cope with. Where a VRLA battery handles on average 300 cycles, a lithium-ion battery handles 5000, 10x the amount. This is critical for an application that requires many charges and discharges for example, a UPS being used for energy storage to power a medical imaging device in regular use.

It is not only the energy storage capabilities of lithium-ion that make them an ideal choice for powering sensitive applications. With a longer design life, the technology also improves the reliability, efficiency and flexibility of the facility’s overall backup power infrastructure. The HTM 06-01 recommends that batteries used for tertiary power supplies, such as those for a UPS, should have a design life of 10 years. Whilst specialist VRLA batteries do meet these guidelines, a standard lithium-ion battery has an average lifespan of 15 years, with no battery replacement necessary.

Until recently, lead acid batteries (VRLA) have been the go-to battery technology for providing stored energy for UPS applications. The high prices and lack of knowledge meant the superior lithium-ion chemistries seemed out of reach for the budget constrained healthcare sector. However, with demand going up and prices coming down, the availability of lithium-ion based UPS systems is on the rise and have become a viable alternative source of stored energy.

Power Control specialise in providing the right UPS solution for the healthcare market and has done so for nearly 30 years. Every UPS system, both static and modular, suitable for healthcare applications are available with either VRLA or lithium-ion batteries and meet all relevant medical regulations including the IEC 60601, HTM 06-01, BS 7671 and BS 6290-4. Contact us to find out more, 01246 431 431, power@powercontrol.co.uk