One of the biggest technical challenges facing commercial drone delivery is battery life. Companies need drones that can carry payloads of packages while still having enough power to travel longer distances and complete multiple deliveries on a single battery charge. Addressing the limitations of current battery technology is a major focus area for many drone delivery startups and tech giants.
Amazon, which has plans for Prime Air drone delivery, has invested heavily in research and development to improve battery energy density and flight duration. In 2021, they patented a new dual-battery configuration that allows drones to quickly swap out depleted batteries in mid-air using robotic arms. This “battery hot-swapping” could theoretically enable drones to fly and deliver indefinitely without needing to land and recharge. This technology would require more advanced autonomous capabilities and adds complexity.
Other companies are taking different approaches. Flytrex, a leader in drone delivery, equips its drones with efficient electric motors and optimized flight routines to maximize flight time and range on conventional lithium-ion batteries. Flight tests have demonstrated payloads of up to 6.6 pounds and flight distances of over 10 miles on a single charge. Like all electric drones, weather extremes still significantly impact battery life.
Wing, owned by Google’s parent Alphabet, focuses on optimizing battery usage through lightweight drone designs and on-board diagnostics to monitor battery health and charging rates. Their latest generation of delivery drones have doubled battery capacity compared to earlier models through advances in battery chemistry and cooling systems. Total flight times are still limited to around 30 minutes based on battery capacity and drone weight with cargo onboard.
To address this, Startup Zipline is taking a very different approach than most competitors by relying entirely on fixed-wing drones versus the traditional multirotor designs with vertical take-off and landing (VTOL) capabilities. Fixed-wing drones are far more efficient gliders capable of traveling much greater distances on less battery power. Fixed-wing delivery drones require runway style launch and landing facilities versus being able to takeoff and land anywhere like VTOL drones. Zipline’s drones can carry 4-6 pounds of medical supplies over a 50+ mile range at speeds around 100 mph while only needing 10-15 minute battery recharges between supply runs. This allows for much higher throughput versus vertical take-off drones limited to a max 30 minute flight time and smaller per-charge range.
In terms of weather resilience, most commercial drone delivery programs today remain limited to fair weather flying since extreme wind, rain, snow and ice significantly impact flight performance and safety. Electric motors and lithium battery packs are also sensitive to moisture and temperature extremes.
Companies are actively working to expand drone operations into more challenging weather conditions via airframe, power system and autonomous software innovations.
Wing has tested delivery drones in light rain and gusty winds up to around 25 miles per hour. Their drones incorporate hydrophobic coatings to shed water and brushless motors sealed against moisture ingress. Advanced computer vision and lidar mapping helps the drones autonomously navigate inclement conditions.
Amazon envisions future delivery drones able to withstand heavy downpours, high winds, icy conditions and even complete deliveries in the wake of major storms or disasters when roads may be blocked. To that end, they are developing drones using hybrid or fuel cell propulsion versus batteries alone for more weather-resilient power. Experimental designs incorporate features like deicing systems, reinforced airframes, and autonomous flight capabilities robust enough to safely route around hazards like downed trees in inclement weather.
One challenge is that regulations currently prohibit routine operations beyond visual line-of-sight, a limitation in low-visibility conditions like heavy rain or fog. Advanced sense-and-avoid and beyond visual line-of-sight technologies still need additional reliability validation by regulators before approvals for commercial BVLOS flights in all-weather conditions.
While drone delivery shows tremendous potential to revolutionize last-mile logistics, battery life limitations and sensitivity to extreme weather remain major technical hurdles slowing widespread commercial deployment. Companies are addressing these challenges through a range of innovative solutions focused on energy density, battery swapping, hybrid-electric or fuel cell propulsion, lightweight materials, autonomous software, and more weather-resilient designs. Should technologies like fixed-wing delivery drones carrying multi-day battery packs or all-weather flight capabilities via hybrid propulsion systems prove out, it could vastly expand the potential use cases and commercial viability of drone delivery worldwide. Regulatory approval of more autonomous BVLOS flight will also be important to unlocking the true potential of drone delivery systems – especially in challenging weather conditions where drones could potentially provide a more reliable option than ground vehicles. Through ongoing technological innovation, the dream of rapid urban drone delivery may soon become widespread reality.