When The Pentagon recently confirmed its ambition to roll out fleets of small, single-use drones, most of the headlines focused on strategy, cost and speed of deployment. But behind the flight plans, one question remains: what will power these expendable aircraft? The answer lies in a technology that has quietly evolved over decades — batteries. Here, Bruce Parkinson, applications engineering and inside sales manager at Ultralife Corporation, explores the role of batteries and how drone manufacturers can make the right choice when selecting theirs.
Unlike reusable drones intended for multiple flights, single-use drones are designed for one mission only. Because they’re unlikely to return, they don’t require a rechargeable power source. Back in the 1940s, when rudimentary expendable drones were first trialled, non-rechargeable battery technology was in its infancy. Alkaline cells had just entered the scene, offering only modest energy density and poor resilience in extreme conditions.
Energy density limitations meant that powering even the most basic single-use drones was problematic, as every drone must have sufficient power for its guidance, communications and control systems. The inability to perform in extreme conditions was troublesome considering that drones operate outdoors at high altitudes.
Today’s lithium-based non-rechargeable batteries address these issues and can even, though still rarely, power the propulsion systems of single-use drones. As in the 1940s, non-rechargeable batteries are mainly used to power radio control systems and flight stabilisers. However, modern drones also feature additional sensors that require more power.
Weighing everything up
When designing single-use drones, there’s always a trade-off between how much energy they can carry, how quickly energy can be delivered, and the power source’s weight. A larger capacity and current means that the aircraft can fly for longer, but the additional weight could make it less agile or limit payload options.
To navigate these trade-offs, manufacturers rely on rigorous testing to understand exactly how their cells perform under demanding conditions. Ultralife recently tested its D-size non-rechargeable cell, the U10026, to prove its suitability for single-use drones. The tests proved that the cell could deliver up to 20A continuously with proper thermal management – a major improvement from previous expectations of 3A. Even at 10–15A continuous, these cells performed well under air-cooled conditions. This unlocks new possibilities for applications requiring uncompromising energy performance.
Modern choices of battery
Today’s drone developers have two options when selecting a power source: primary (non-rechargeable) or secondary (rechargeable) batteries. For expendable drones, primary lithium cells are often preferred because they can store significantly more energy than rechargeable cells of the same size. This higher capacity allows compact aircraft to carry heavier payloads or achieve longer ranges without increasing airframe size.
Meanwhile, multi-mission drones – those expected to return and recharge – typically use lithium-ion packs. These have largely displaced older lead-acid designs thanks to their longer cycle life, higher reliability and steady power output. All these features ensure modern drones and all their accessories, such as cameras for surveillance and mapping, can successfully operate over long missions.
Both rechargeable and non-rechargeable battery packs vary based on the cells used and the way they are integrated in the pack. Therefore, as more drone manufacturers look to produce single-use fleets following the Pentagon’s announcement, it is advisable to consider the power source early in the design process. Correct cell selection and pack design, factoring in weight, current draw and endurance, not only means the drone will perform well but may help inform the required size and shape of the drone itself.
