Can the uninterruptible power supply (UPS) be activated at any time?
We increasingly rely on technology to provide us with a sense of security: cameras, emergency phones and even security lighting all give us a sense of reliability, and let us know that we can always use them if we need to. Ensuring availability in an emergency depends on an error-free power supply, which in turn means high-quality backup batteries. But how do you know that the backup battery is really safe?
The problem plagues device makers who rely on batteries for emergency power; How do you know it will work when you need it most? This is especially important for manufacturers of uninterruptible power supplies (UPS), whose sole purpose is to ensure the power supply of computer systems or medical devices in the event of a failure of the main power supply. In these cases, the provision of electricity and the supply of electricity within a defined time and supply tolerance is extremely necessary.
Most backup batteries use multiple valve-controlled lead acid (VRLA) cells to form an integral battery. Despite being called “maintenance-free,” the technology has well-known drawbacks, any of which can make batteries inefficient or even completely ineffective.
Therefore, weak, aged, or otherwise “unhealthy” batteries pose a serious hazard to these systems and require regular maintenance to check their state of health (SOH) and State of Charge (SOC). No matter how frequent these services are, there is still a risk of battery failure between maintenance checks. To overcome this, some companies are turning to systems that provide continuous in-situ SOH and SOC monitoring.
Continuous monitoring
This may seem like a simple solution, but in reality it is economically difficult. Continuous monitoring programs typically require a 50 percent increase in battery costs, or up to 70 percent when installation and operation are taken into account. In the face of such high costs, it may be more economical to replace batteries regularly before indicating the mean time to failure (MTBF) of the end of battery life. However, as with routine maintenance, this is fraught with uncertainty, as environmental conditions have a big impact on the MTBF of the battery.
Manufacturers are therefore turning to low-cost continuous monitoring systems to fully diagnose the battery’s SOH and SOC under all conditions. In March 2007, LEM, a specialist in the supply of these smart transmitters, collaborated with RWTH Aachen University, a leading authority in the field of diagnosis and management of sealed and exhaust lead-acid batteries, to establish the direction for the development of advanced low-cost battery monitoring management.
While other manufacturers pursue more “fashionable” battery technologies, RWTH Aachen University has established and strengthened its technical center to focus on the most mature and widely sold battery chemistry processes. Lem-aachen has formed a long-term partnership to study the failure modes of VRLA (valve-controlled lead acid) rich liquid and colloid batteries and to develop next-generation monitoring and analysis systems, including SOH and SOC.