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Telcordia NEW GR, Generic Requirements for Lithium Batteries for Use in Telecommunications Facilities

Background

Telecom carriers rely on the standby energy of batteries to sustain communications activity during AC power interruptions and outages in Central Office (CO) and Outside Plant (OSP) facilities. Telecom carriers must provide adequate standby and emergency power, to increase customer satisfaction, boost shareholder confidence, and enhance network reliability. To achieve these goals, carriers have relied on the standby energy of flooded Lead Acid storage (LA) cells and AC engines in the CO and Valve Regulated Lead Acid (VRLA) or flooded Nickel Cadmium (Ni-Cd) cells in the OSP. Carriers have been very satisfied with the technical capability of flooded lead acid cells for over 50 years to provide adequate standby and emergency power, high reliability, and minimum intervention by carrier personnel. Unfortunately, carriers have not been satisfied with the lifecycle costs of OSP batteries, especially VRLA. Since the start of network decentralization 20 years ago, carriers have desired greater reliability and performance from the early designs of the products for uncontrolled and harsh OSP environment.

Network Transformation

As the network evolved and as different battery technologies were introduced, carriers and manufacturers have engaged Telcordia as a trusted industry advisor and moderator in the development of generic requirements that define the safe and reliable operation of these battery systems. The following Telcordia standards documents are examples of the diligent collaboration between the industry and Telcordia:

  • GR-232-CORE, Generic Requirements for Lead-Acid Storage Batteries, Issue 1, July 2003
  • SR-4228, VRLA Battery String Certification Levels Based on Requirements for Safety and Performance, Issue 1, December 1996
  • GR-1200-CORE, Generic Requirements for Accelerated Life Testing of Valve Regulated Lead Acid Batteries at High Temperatures, Issue 1, September 2003
  • GR-1515-CORE, Generic Requirements for the Detection and Control of Thermal Runaway in VRLA Batteries, Issue 1, October 1994
  • GR-3020-CORE, Nickel Cadmium Batteries in the Outside Plant, Issue 1, April 2000.

Telcordia's role as a trusted independent advisor has been a significant help to battery users and vendors interested in the economics, design, development, testing, deployment, operation, and maintenance of telecom batteries. Our independent position is particularly needed for the safe and reliable evolution of the network from a circuit- to a packet-based network.

The exponential growth of the Internet and the emergence of fiber optics, wireless mobile devices, and broadband communications have revolutionized the manner in which society communicates. Subscribers want more than voice services on traditional wired lines — they want communication services that provide voice, data, and video. To meet this transformation and compete with cable and wireless service providers, carriers are redefining their communications network from a circuit to an Internet Protocol (IP) infrastructure. The decentralization of the network, transformation of the network to broadband, and the proliferation of broadband product vendors has given carriers the ability to offer broadband services to their existing and new customers at competitive prices. However, it has always placed more of an economic burden on carriers as they have to expend capital to construct the broadband network. Carriers need to determine creative and effective ways to minimize costs, optimize operations and revenues, while still providing a high quality of service for this transformation to make economic sense.

Emergence of Lithium Batteries

The decentralization of the network has placed a large number of remote terminals in the stressful conditions of OSP. There is no secret that some carriers are concerned with the reliability and performance of presently embedded OSP batteries. Carriers are frustrated with the lifetimes of these standby power systems and with the unexpected and untimely burden and expense of having field engineers prematurely replace weak or failed batteries. The life of the batteries depends on their temperature – in warmer climates batteries have shorter lifetimes. Carriers introducing broadband services and focused on minimizing costs desire a truly maintenance-free OSP battery product that can provide remote monitoring, the reliability of flooded CO cells, can operate in extremely cold and hot environments, and can provide greater energy density. Within the last few years, carriers looking for increased OSP battery reliability and performance have shown interest in deploying rechargeable, maintenance-free Lithium batteries in their outdoor networks.

Researchers have been very interested in the energy storage capabilities of Lithium for over 30 years. The interest lies in the fact that Lithium is the lightest of all metals, has the greatest electrochemical potential, low rate of self discharge, broad temperature range of operation, and provides the largest energy content when compared to other chemistries. For example, Telcordia researchers invented a Plastic Lithium-Ion (PL-iON) technology that superseded commercially available Lithium cells. Extra care must be taken in operating Lithium metal as it is very reactive and will detonate if mistreated during operation (i.e., rechargeable Lithium metal cells used in mobile phones inflicted burns to a man's face in the early 90s, forcing the recall of several mobile phones). The increased energy density of Lithium means a greater focus must be placed on safety when operating rechargeable Lithium cells. Hence, Lithium battery vendors require precise safety circuits that monitor overcharge, undercharge, over discharge, overheating, and external short circuit events. Internal short circuits cannot be monitored by the electronics; hence, the carrier and supplier must take critical steps to ensure that the cells do not short and detonate even in a fire. Cell shorting could also cause thermal runaway but only if the battery has a recombination reaction that generates heat. The advantages of the Lithium battery are obvious, but vendors and users must help ensure that the safety mechanisms integrated in the battery pack allow the product to fail safely without detonation even in a fire.

The Need for Lithium Battery Generic Requirements

In seeking an economic advantage and with the emergence of vendors manufacturing secondary Lithium batteries for telecommunications use, carriers and suppliers are quite eager to operate this technology in the OSP. However, the battery community and all interested parties should opt for consensus prior to full deployment because:

  • Lithium Can Explode - Carriers and suppliers need a battery-safety design program to ensure that the internal construction of Lithium batteries does not expose the lithium to moisture or fire. Lithium is very reactive and will react violently if in the presence of moisture or fire. Carriers should ensure that battery designs and construction maintain the environment needed to limit moisture and prevent fire. Testing results detailing the integrity of the battery construction should be reviewed by the user prior to deployment. Remember, internal short circuits cannot be monitored by the electronics; hence, the carrier and supplier must take critical steps to ensure that the cells do not short and detonate. For example, internal short circuit testing should be performed at the individual cell level in conjunction with external short-circuit testing.
  • NEBS™ Testing Is Not Enough - Third-party NEBS testing provides physical protection requirements for all network elements and helps to identify environmental compatibility problems before production. To receive NEBS compliance, a network element such as a battery must undergo a series of environmental, mechanical, and electrical tests. A battery cannot be deployed in the field without complying to NEBS. However, NEBS does not validate the compliance of a battery design to telecom safety and functional requirements. In other words, complying with NEBS testing does not necessarily mean that product will operate and perform as expected. Consensus on the electrical, chemical, physical design, quality and reliability, documentation, and training requirements for Lithium batteries is needed to ensure that the product performs as expected and will not endanger staff or infrastructure. Moreover, users should require nail penetration, overcharge, over discharge, reversal, and overheat and temperature shock testing results.
  • NEBS Does Not Focus on OSP - NEBS applies to network equipment intended to function in CO and customer premises locations and not in OSP environments, which have broader temperature and humidity swings and also different, and often higher, levels of particulates and chemical pollutants. Telcordia GR-3108-CORE, Generic Requirements for Network Equipment in the Outside Plant, Issue 1, July 2004, provides environmental performance requirements for network equipment intended to function in the OSP.
  • Verifying Electronics Reliability - Telcordia GR-232-CORE, Reliability Prediction Procedure for Electronic Equipment, stipulates that the electronics used in the network must provide at minimum certain Mean Time Before Failure (MTBF) failure. This metric is especially important for the safety circuits that govern the Lithium cells. Premature failure of the safety circuitry could result in detonation if the cells are overcharged, undercharged, or shorted. It is the responsibility of carriers to make sure that supplier-electronics reliability calculations and results are sufficient and suit their needs. Generally, any additional circuitry decreases system reliability, but in the case of Lithium batteries, the safety concerns go beyond reliability reduction.

Telcordia Invites Participants for Development of Generic Requirements for Lithium Batteries

Telcordia desires to address the concerns regarding the lack of industry discussion and consensus on requirements for Lithium batteries by inviting the battery users and vendors to participate in development of Generic Requirements for Lithium or Non-Aqueous Batteries.

Industry consensus is needed for the Lithium battery because without it carriers will be dependent on the solutions of individual vendors, and the market penetration will suffer. In order to define industry standards, Telcordia is ready to work with industry leaders on defining standards for the use of Lithium batteries in telecommunications facilities.

Telcordia is proposing the development of a Special Report (SR) and a new family of Generic Requirements (GR) documents consisting of a GR document for each Lithium battery type (i.e., Lithium Metal Polymer, Li-Ion, and Li-Ion Polymer) (or multiple GR documents). The SR would provide information on the technical aspects of the various Lithium-based technologies and their application in various telecommunications environments. The details would be specified in the GR document(s) anticipated to contain specific requirements for each of the Lithium-based or other non aqueous batteries identified in the SR.

Telcordia anticipates addressing the following issues with the GR document for Lithium Batteries:

  • Plant Voltage Limits
  • Thermal Management
  • Protection Circuitry
  • Electronics Reliability
  • Service Life versus Cycle Life
  • Impact on Overall System Reliability
  • Other issues identified by the funding participants.

Note: Similar topics would be covered by a Li-Ion document, but with additional topics on the role of cathodes, anodes, and electrolyte.

Summary/Path Forward

Telcordia is ready to serve all interested parties in this endeavor and will maintain our role as an independent trusted industry advisor. Telcordia brings extensive knowledge and experience to this GR effort. Researchers such as Dr. Thomas O'Sullivan have provided invaluable work in the design, development, and generation of requirements for embedded telecom batteries. Dr. Thomas O'Sullivan has spent over 30 years in the industry collaborating with the battery community.

Pursuant to provisions of the Telecommunications Act of 1996, related to the development of industry-wide generic requirements, Telcordia invites all interested industry members to participate in the development of Lithium or Non-Aqueous Battery GR(s). If your company is interested in participating in this activity, please contact Telcordia. The resulting document will only be available through the purchase of an Enterprise License. Such a license is included in the participation fee for this project.

To proceed with a complete Issue 1 of this new GR(s), it is expected that Telcordia will need five industry participants. While the project can proceed with fewer participants, the scope of work may need to be scaled back accordingly. Participating industry members will be apprised regularly of project status and change in scope.