The benefits of smart battery integration in modular power systems
By Darren Salter, Eaton Product Line Manager – PQ/Telecom DC and Chris Barson, Eaton Product Manager – PQ/Telecom DC
Friday, 30 April, 2021
Complete integration of the power system controller with the batteries’ BMS secures the true benefits of lithium technology for critical power systems.
Critical power systems within the communications, utilities, and mining segments have in the past utilised valve-regulated sealed lead acid (VRLA/SLA) battery technology for power backup. VRLA batteries offer a basic design without any integrated monitoring or control, and are usually controlled by a modular DC power system. Unfortunately, such a lack of self-monitoring and self-management is out of pace with the modern shift towards digital technology.
High maintenance costs an issue
The absence of the built-in intelligence means that for VRLA batteries there is an ongoing requirement for frequent scheduled (and unscheduled) maintenance site visits by knowledgeable expert technicians during the life of the batteries.
Monitoring systems are available that can provide added battery visibility compared to a standard power system, but the information gained remains basic. VRLA battery monitoring systems are also typically a separate system to the charger, resulting in a higher starting cost, which results in some users choosing to forego this added component.
In any case, the battery monitoring device does not remove the requirement for field technicians to perform scheduled routine maintenance, with its associated costs.
Making battery banks smarter
Nowadays a key technology shift has been occurring with the move to smarter battery systems such as those based on lithium cells. Lithium batteries with built-in multipart battery monitoring systems (BMS) are a key digitisation advancement over VRLA technology, as they not only provide a significantly higher level of monitoring of the battery bank than that which could be achieved with dedicated VRLA monitoring systems, but can also remove the need for periodic battery maintenance entirely.
The built-in BMS fitted within most telco-grade lithium systems are highly sophisticated and can self-manage most aspects of the charging and discharging functions — down to the single cell level — providing balancing that was traditionally unavailable to VRLA batteries.
Integration is key
Many modular DC critical power systems and lithium batteries as offered as separate components of an ‘intelligent’ and ‘integrated’ solution. However, despite obtaining some benefit from such a solution with a quality lithium battery, multiple essential capabilities of the solution are simply unused and unavailable when designed in this way.
To secure the true benefit of lithium technology within a critical power system, a comprehensive integration of the communication between the power system and the battery’s internal BMS units must be provided. Without full integration, many requirements of a truly reliable critical power system cannot be achieved — such as accurate and functional control of system features like battery current limiting, multi-stage charging, intelligent generator start/stop control, and peak load reduction, for example.
As is the case for most companies today, the focus on technology is important, but providing a safe working environment for employees is also paramount. Batteries are a frequent point of concern for OHS teams, as VRLA batteries are permanently energised and present a risk to personnel and equipment during transit, installation and maintenance. Despite the likelihood of accidents being low, they remain a concern to many who are looking for ways to minimise the potential for harm.
Reputable 48 VDC long-life telco-grade lithium iron phosphate (LiFePO4/LFP) batteries will typically allow for de-energisation of battery terminals either manually by the user, or automatically via the in-built BMS if a protection event occurs, such as short circuit. LFP battery technology typically also emits no gases — unlike VRLA batteries which emit hydrogen — and have an internal chemistry that includes no toxic or hazardous materials. Even in worst-case scenarios LFP batteries are virtually incombustible.
True integration lowers TCO
Properly engineered critical power systems — with true integration of components — remain at the heart of achieving the essential functional capability and the lowest total cost of ownership (TCO). Installing non-integrated smart devices together does not make a smart solution; it instead adds to TCO with unnecessary site visits, reduced functional capability and reduced remote visibility. Users should not accept anything less than a truly integrated solution.
For more information, visit www.dcpower.eaton.com/australia
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