Grid availability in India is unstable and short in supply and as result base stations have to deploy diesel genset, batteries and energy alternatives to fulfill the gap of electric supply to provide mobile user undisruptive signal strength for communication. Traditional heavier and bigger valve-regulated lead-acid (VRLA) batteries were used as energy storage device to provide backup to base stations.  VRLA has limitations like short discharge time, long charging time, short life, cell pilferage issue and require air conditioning at high temperature.

Due to strict regulation in place or planned worldwide on CO2 emission by diesel generators; telecom operators have started thinking about alternative solution to reduce operating cost of fuel, noise pollution, maintenance cost of generators and fuel pilferage. Lithium batteries are answer to all of the above operational and socio-political challenges.

Lithium batteries with long discharge time, short charging time, no cell pilferage issue, high life and up to very high temperature (55 deg C) does not require air-conditioning. Lithium batteries unlike diesel gensets have no fume emission, and make for low maintenance and low operational cost energy source to provide undisruptive power supply to base stations in case of unstable grid conditions.

Also, lithium batteries are compact in size and therefore address the issue of space crunch in base stations. Lithium ion batteries can be used to reduce space by 50 per cent and for making room for more telecom equipment required in 4G network. Since micro base stations are pole mounted and has less space for any deployment so lithium ion is best power solution. Lithium ion batteries are lighter in weight so they can be easily lifted to micro base station’s vertical deployment.  Three lead acid batteries can be replaced by one lithium ion battery thereby increasing capacity and decreasing weight.

Lithium batteries are inbuilt with an advance battery management system (BMS) with over discharge, overcharge, over current and overheat protection to ensure communication.  BMS optimises the management of float charging, remote monitor of system by GPRS. Battery’s state of charge and other parameters can be observed remotely online and any battery problem can be addressed quickly compare to VRLA batteries.  BMS can combine the lithium battery, diesel genset and existing VRLA battery and combined operational data can be observed to study effectiveness and efficiency of power supply to base stations. Real time dashboards to monitor the battery usage trends, reduce site visits and human involvement.

History says that lithium ion batteries were expensive in nature in evolution phase and were used in small applications like laptops, phones and cameras. As time progressed, the design of the batteries improved and the technology behind the battery management systems became more sophisticated, improving the performance and cost effectiveness of the applications. The improvement in performance and reduction in cost led to lithium ion dominate small battery segment and applied to industrial use like base stations, power plants and electric vehicles. Lithium ion batteries are noise free, spill proof and emission free in nature so government’s commitment to reduce carbon foot prints can be fulfilled.  Another advantage is economic value of the lithium battery deployment; return of investment is expected to be within two and half years. 

Lithium batteries are key to successful 4G network deployment in India with grid deficiency. They act like energy storage device supporting green energy efficiency. Country needs to upgrade telecom infrastructure to adapt high speed data transfer 4G network.

With decreasing time average rate per user, telecom operators are decreasing rates/ minute to remain competitive. Advantages such as low maintenance cost and high fuel cost saving make lithium ion batteries perfect choice for operators. And nonetheless, lithium ion batteries will help reduce use of diesel gensets and thus contribute to reduction in carbon foot print by building green future.

(Contributed by B. Madhu Babu, Head Electrical Design, Bharti Infratel Limited)