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Case Study

Controlling Telecom Tower Costs Using Lithium Batteries

System Overview

Where generators provide power at remote telecommunications sites, system reliability is critical. Many commercial systems include two generators that operate in rotation. System operators realized they could decrease engine runtime by including a battery and charger into the DC bus.

The battery provides constant power for the electrical loads. The generator runs three to five hours every time a lead acid battery needs to be recharged.

Challenges

In remote areas, the price for fuel delivery can exponentially increase costs. Routine site maintenance is often limited by seasonal access. Emergency generator maintenance can require very expensive labor and transport costs. Lead acid batteries require regular onsite testing and maintenance, in addition to relatively short cycle life. This is not ideal.

The Solution is Lithium

Battery choice is the most critical decision to control the telecom tower’s costs. Lithium batteries feature fast charge, higher enery density and remote monitoring that make this new battery an ideal fit for reliable remote power.

Lithium Iron Phosphate (LiFePO4) batteries are the safest type within the family of lithium batteries. Lithium Iron batteries are superior in energy efficiency and cycle life compared to lead acid batteries, lowering labor costs for replacement and decreasing generator runtimes.

Each individual cell in Lithium Iron battery can be monitored remotely through an online portal. This saves the cost of onsite resistance testing which lead-acid batteries require to monitor battery health and performance.

Lithium batteries have revolutionized consumer electronics in the 21st century with their reliability and energy density, and now this proven technology is poised for further market penetration in mission-critical remote telecom sites.

Improved Efficiency and Longer Cycle life

Lithium Iron batteries offer three-times the usable life of a lead-acid battery in daily cycle applications. Longer cycle life eliminates site visits to replace failing battery banks, freeing up company time and resources.

Battery charge efficiency is greatly improved with Lithium Iron, which reduces generator run time - saving fuel and maintenance costs.

Lead acid batteries waste as much as 30 percent of energy put into them due to efficiency losses, so if you provide 100 amps of power you’re only storing 70 amps in the battery.
1 Lithium is able to hold more of this power, storing between 9 and 100 amps of the same charge current thanks to improved efficiency.
2 Lead acid batteries suffer from slow charging in the top half of the battery – which is the part used the most during daily use. The final 20% of a charge cycle requires an “absorption” stage, which tapers charge current while holding a set voltage. This requires a longer generator run, and if charging with solar, the sun may set before the battery is able to reach full charge. Failure to complete a full charge cycle can result in premature aging and reduce the usable life of a lead acid battery.

Lithium Iron batteries do not require this wasteful absorption stage, can be fast charged, and are able to hold more of the incoming power thanks to better efficiency.

Benefits of energy storage at sites powered by generators:

Lithium advantages over lead acid:

Carrier-grade microwave radios and multiplexers are supported for 24/7 operation by an Iron Edison Lithium Iron 5000Ah 52V battery. Inverters from Schneider Electric (right) provide AC power for other site loads.
1000Ah single format prismatic cells are used for fewer parallel connections. Each cell has a cell board card from the BMS, which keeps the pack balanced and provides real-time data that can be monitored online.

50% of Lead Acid Life

is at low efficiency, causing longer generator run times and increased costs of fuel and maintenance.

Inside the control room of an off-grid telecom site powered by renewable energy

(24) MidNite Classic charge controllers regulate solar power to battery charging.
Telecom repeater equipment (Alcatel-Lucent MDR-8000) and Schneider Electric battery inverter for AC loads.
Iron Edison 5000Ah 52V Lithium Iron Phosphate (LiFePO4) battery and cladded enclosure Battery has 260 kWh total capacity.