The fail-safe availability of process-relevant systems and components begins quite fundamentally with the uninterruptible power supply (UPS) and the associated protection against power failures, flicker, fluctuations or voltage dips in the 12V or 24V DC power supply. Decentralized and compact DC UPS systems are increasingly being used for this, which can be placed directly on the machine or integrated into the systems.

Which factors must developers consider when selecting and dimensioning DC UPS systems?
The requirements for an uninterruptible DC power supply are diverse and individual. Last but not least, such an "insurance against power outages" should be implemented as cost-effective, durable, flexible and reliable as possible. In order to achieve these goals optimally, a detailed analysis of the application and detailed knowledge of the advantages and disadvantages of different battery technologies is required – as well as a holistic view of the TCO (Total Cost of Ownership). The white paper "Selecting the right battery technology for long-lasting and safe DC UPS systems" from Bicker Elektronik shows the technological differences and selection criteria for energy storage devices.

Supercaps, lithium-ion, pure lead-tin and lead gel batteries
Supercaps, lithium-iron-phosphate cells (LiFePO4), conventional lithium-ion cells (LCO / NMC), pure lead-tin and classic lead gel batteries are compared in terms of numerous parameters, i.a. cell structure, safety, energy and power density, lifetime, current carrying capacity, operating temperature range, maintenance, transport and storage, initial and follow-up costs. Using the example of modular DC UPS system UPSI from Bicker Elektronik, which is equipped for flexible use of different battery technologies, the structure and function of control and charging technology including battery management system (BMS) are explained.

Absolutely maintenance-free supercap energy storage
In the area of short and medium bridging times, the white paper describes the design, function and circuitry of maintenance-free supercaps as highly efficient and particularly long-lasting energy storage devices with more than 500,000 charging and discharging cycles. PC-based systems can be safely shut down in case of prolonged power failure, actuators moved to a defined home position or the current process step in the automation can be completed, just to name a few application examples. Unlike batteries, which store energy by the detour of a chemical reaction, supercaps are based on electrophysical principles and therefore are quickly charged and ready for use.

LiFePO4 – The safe and durable lithium-ion battery technology
For longer bridging times, lithium-ion technology is ideal. When selecting a Li-ion energy storage for DC UPS systems, however, a closer look at the used cathode material is recommended. Especially cells with chemically and thermally unstable cathode material such as lithium-cobalt-oxide (LCO) or lithium-nickel-manganese-cobalt-oxide (NMC), under certain conditions, cell-internal exothermic chemical reactions can occur which ultimately result in an uncontrollable "Thermal Runaway " (see burning electric cars and mobile phones). With lithium-iron-phosphate (LiFePO4), a much more stable chemical compound with increased safety and around ten times higher cycle stability is available for the cathode material. The white paper shows the details.

Battery Management System (BMS)
Additionally the white paper explains the structure and differences of lithium-ion battery technologies and the functions of the BMS (battery management system), which is absolutely essential for lithium-ion batteries: protection, safety and monitoring functions and cell balancing for optimal use of total energy storage capacity. Further the battery relax mode to extend the life of lithium-ion batteries and the system present function to increase safety and shelf life of battery packs.

Free white paper provides valuable expertise
The white paper conveys valuable expertise and relates the various aspects to each other so that system developers and project leaders can make future-proof and sustainable decisions based on a well-founded knowledge base. The white paper is available for free via website www.bicker.de/whitepaper in English and German language.

Direct link to white paper (English):
https://www.bicker.de/index.php/eng/Support/Download/Whitepaper/Whitepaper-Selecting-the-right-battery-technology-for-long-lasting-and-safe-DC-UPS-systems 

Direct link to white paper (German):
https://www.bicker.de/index.php/bicker/Support/Download/Whitepaper/Whitepaper-Auswahl-der-richtigen-Batterietechnologie-fuer-langlebige-und-sichere-DC-USV-Systeme