Passing the 15-year mark — An analysis of Ni-Cd battery performance in remote terminal applications

摘要

In 1997, industrial Ni-Cd (Nickel Cadmium) batteries were first trialed, leading to commercial deployments in telecom remote terminals (RT) in all regions of the USA and in many other parts of the world. Today, over 100K Ni-Cd battery strings are in operation. The battery design was adapted for high energy density, its resilience to harsh and un-controlled environments, and its ability to operate with little or no maintenance throughout its lifetime. Its form factor allowed a direct replacement of legacy batteries (typically Valve Regulated Lead Acid (VRLA)) in the existing OSP (OutSide Plant) infrastructure. The main reason telecom operators consider utilizing Ni-Cd's is due to its inherently long standby lifetime, particularly where operating temperatures are the highest. Over the last 19 years, several field studies (reference [1][2][3][4][5][6]) were conducted to assess the performance (as found capacity level) and water consumption (needed maintenance) of many field operated Ni-Cd battery strings. The results of these studies were published at previous conferences which marked the 5 year [1] and 10 year [2] observations. Recently, another field study was conducted marking the 15 year observations. This paper will summarize and discuss these recent findings. Using industry standardized practices, the physical assessments, discharge performance, electrolyte levels, voltage characteristics, and float current characteristics are reported and discussed. The findings demonstrate that Ni-Cd batteries can operate for more than 15 years in an un-controlled remote terminal without requiring a replacement and with no required maintenance. The conclusions presented in this paper allow a cost of ownership comparison to be based on field experience in un-controlled RT environments.