Miniaturized battery-powered solutions are becoming essential to military/aerospace applications, as design engineers are seeking to pack increased amounts of system functionality into smaller footprints without compromising performance or reliability.
An innovative solution is provided by Tadiran lithium metal oxide batteries. This new type of high energy battery currently being deployed in mil/aero applications, including: avionics; ordinance fuses; missile systems; GPS tracking; emergency/safety devices; along with shipboard and oceanographic devices.
A prime application for their use is powering the emergency recovery system (ERS) of military UAVs. Due to the financial and tactical value of a UAV as a sensitive asset containing sophisticated and proprietary technology, added precautions were required to help protect these unmanned aircraft from an uncontrolled crash landing.
In the event of a catastrophic power failure to the UAV’s main engine during a training or combat mission flight, the battery-powered ERS would provide back-up power for the aircraft’s guidance system, thus allowing the unmanned aircraft to glide a safe landing. Use of the ERS helps prevent this sensitive technology from falling into enemy hands while also saving taxpayer dollars by extending the service life of the UAVs.
The ERS is powered by a custom battery pack and enclosure consisting of 96 AA-size lithium metal oxide batteries, resulting in an extremely compact power supply that can deliver up to 32V/480W of power. The small, lightweight battery pack weighs just 2 Kg, including the metal enclosure, which further improves the aircraft’s aerodynamics while freeing up added space to maximize the payload of surveillance equipment. By contrast, an equivalent battery pack made with D-size primary lithium batteries would have resulted in a power supply that was much larger and heavier.
Lithium metal oxide cells are constructed with a carbon-based anode, a multi metal oxide cathode, an organic electrolyte, and a shut-down separator. This cell design features an extremely high power-to-size ratio. For example, a AA-size lithium metal oxide cell can deliver up to 2 Wh of energy with a nominal voltage of 4V and a discharge capacity of 1,100 mAh, including the ability to generate 15A pulses and 5A continuous current.
Lithium metal oxide batteries deliver up to 20-year storage life due to a very low annual self-discharge rate of less than 1% per year. Military grade TLM Series batteries are designed to withstand extreme temperatures (-40°C to 85°C), and complies with MIL-STD 810G specs for vibration, shock, temperature, salt fog, altitude, acceleration (50,000 gn), and spinning (30,000 rpm). These ruggedized batteries also meet the current UN 60086 standard for crush, impact, nail penetration, heat, over-charge, and short circuit.
batteries are also utilized in smart munitions that were traditionally powered by reserve/thermal batteries: a legacy technology that has had remained virtually unchanged for decades. Reserve/thermal batteries operate by keeping the chemical constituents of the electrolyte separated, but then require a customized solution, including the use of squibs and layers of thermal insulation, to manage the powerful chemical reaction that occurs when the constituents are mixed. This blending process also causes a momentary power delay.
Once initiated, the chemical reaction must continue until the battery is exhausted. In high reliability applications such as smart munitions, this can be highly problematic, as reserve/thermal batteries cannot be tested for system readiness, which greatly increases the risk that the smart munition could be a “dud.”
Lithium metal oxide battery chemistry also offer a more affordable commercial off-the-shelf (COTS) solution. By contrast, reserve/thermal batteries must be customized to each application.