When designing an unmanned aerial vehicle (UAV), engineers must continually seek to reduce size and weight wherever possible in order to improve aerodynamics and free up critical space to deploy additional sensors and instrumentation.

Miniaturization and weight reduction were forefront on the minds of the engineers responsible for designing an air reconnaissance UAV’s emergency recovery system deployed in Iraq and Afghanistan. A back-up power supply was designed to provide redundant guidance control in case of main system failure, enabling the UAV to glide to a safe landing. The backup capability provided an ideal opportunity to deploy a new generation of high-power lithium metal oxide batteries.

Constructed with a carbon-based anode, a multi-metal oxide cathode, organic electrolyte, and a shut-down separator, TLM Series lithium metal oxide cells from Tadiran Batteries feature a high energy-to-size ratio. A AA-size lithium metal oxide cell, for example, delivers up to 2 Wh of energy with a nominal voltage of 4V, a discharge capacity of 1,100 mAh, and both 15A pulses and 5A continuous current.

Lithium metal oxide batteries also offer a 20-year storage life due to a low annual self-discharge rate (less than 1% per year). The little cells withstand extreme temperatures (-40°C to 85°C) and comply with MIL-STD 810G specs for vibration, shock, temperature, salt fog, altitude, acceleration (50,000 gn), and spinning (30,000 rpm). The components also meet UN 60086 standards for crush, impact, nail penetration, heat, over-charge, and short circuit.

To power the UAV’s emergency recovery system, a 32V/480W custom battery pack and enclosure was developed using 96 AA-size lithium metal oxide batteries. The resulting compact power supply, including the metal enclosure, weighed 2 kilograms — a far less bulky option than a battery pack constructed of D-size primary lithium batteries.

High-energy lithium metal oxide batteries are currently being deployed in numerous applications, including avionics, ordinance fuses, missile systems, GPS tracking and emergency/safety devices, shipboard and oceanographic devices, automatic external defibrillators (AEDs), and surgical power tools.

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