Modern Warfighters rely upon tactical electronic devices to achieve operational overmatch against their foes. However, the same technologies that enable such capability also present operational energy challenges.
For the dismounted Warfighter this typically means having to carry numerous spare batteries of multiple types in order to have enough power for a 72-hour operation. Compounding this burden is the fact that many devices require unique batteries that work only with that device – either because of different mechanical connection or electrical requirements.
This lack of power source commonality has placed a heavy burden on the Soldier, often amounting to 20-40 lbs. or more of spare batteries – in a total operational load of 100 lbs. or more. Needless to say, this erodes both physical and cognitive performance, with also degrades readiness, operational performance, and lethality.
The illustration below illustrates the various types of batteries needed to power typical dismounted tactical electronic devices.
Scoping the Challenge
As the US Army began numerous modernization initiatives in recent years, it became clear that the power demands of new tactical electronics systems would require even more spare batteries to be carried by the Soldier. Using data from the US Army’s Command, Control, Communications, Computers, Cyber, Intelligence, Surveillance and Reconnaissance Center (C5ISR) power team, the graph below illustrates this ever increasing demand for power.
Although not shown on the previous graph, the Army’s solicitation for Next-Generation Squad Weapon (NGSW) specifications included the requirement for future incorporation of a powered rail system with a common power source mounted on or attached to the weapon. This requirement was due to the next-generation aiming and targeting systems intended for the NGSW weapons and highlighted the importance (and urgency) of devoting efforts towards creating standardized families of batteries for tactical electronics.
Now, there are valid reasons why different military devices have traditionally needed different batteries:
- Output Voltage
- Different devices operate at different voltages – ranging from 3.3-21V – and cell chemistry, cell configuration, and power requirements dictate what a battery’s output needs to be
- Form Factor
- A device’s required energy drives the number and type of cells used in a battery, which it turn shapes a battery’s size, weight, and form – as to human factors such as ergonomics
- Connection Interface
- Several commonly used military batteries are similar in size, weight, and energy capacity but are not interchangeable as they have different electrical and mechanical connections
- COTS Compatibility
- Military electronics equipment traditionally isn’t interoperable with commercial devices – as there hasn’t been a need to COTS-compatibility, military equipment also needs to meet more rigorous standards of robustness
In studies from 2018-2019, the C5ISR team also identified what they saw as three fundamental human factors design criteria for a family of portable / handheld device batteries:
- Must have a common interface
- Keep a constant 2D cross section
- Expand in 3rd dimension to increase capacity
However, the team also established that the lack of a common battery/cell voltage would limit interoperability even more than a common form or mechanical interface.
Battery Standardization Vision
The team’s goal was to develop a family of standard, interoperable batteries that with adaptive power delivery and a common connection interface. This would have the benefits of reducing the Soldier’s battery burden – while also improving operational capabilities and simplifying logistics and reducing overall program costs. Leveraging commercial technologies and components would additionally provide overall program cost savings through standardization and economies of scale. This vision of battery standardization was illustrated as shown below.
A Path Forward
USB protocols are defined by USB Implementers Forum (USB-IF) – the group of companies that has developed, certified, and shepherded the USB standard over the years, and now counts more than 700 companies in its membership.
USB protocols have come a long way since the initial standard was launched in 1996 to standardize the connection of peripherals to personal computers. It is fact no exaggeration to say that mobile USB devices have now totally transformed the way that consumers and businesses utilize communications and information technology.
Mobile technologies are also transforming operations in the tactical environment. Operators are relying more and more on the power of mobile solutions to make informed decisions that impact mission success. One example of this is the Nett Warrior (NW) system which uses a secured, COTS mobile device running the Android Team Awareness Kit (ATAK) app to enhance operational capabilities.
While mobile platforms have proven to be a force multiplier for our Warfighter, the power and equipment needed to support these devices has resulted not only in an increase to the Soldier’s combat load but also adds a new layer of complexity.
In response to that challenge, the Army developed the Conformal Wearable Battery (CWB). This ergonomic power source was originally developed in 2008 and was a significant step forward in supporting the need for a wearable power solution. Referring back to Figure 2, we can see however that only 10 years after its introduction, the CWB was already becoming over-stretched in delivering the amount of power needed by the modern Warfighter.
Built on a culture of innovation, Xentris Wireless has worked with leaders in the commercial mobile device industry to solve similar challenges as those faced by the military – how to provide power, more efficiently, with less weight and bulk, for mobile products with more advanced capabilities.
At the heart of this evolution in power capabilities are USB technologies – which have improved dramatically in recent years. USB Power Delivery (PD) 3.0 introduced in 2019 has the capability to charge devices at 100 watts. But it’s not just about raw power, power also needs to be managed and delivered at the right rate for more efficiency and faster charging times – both the charger and the device need to be able to communicate the maximum they are capable of or else they will default to a lower charging rate. This continual source / sink communication is what happens with USB PD and Programmable Power Supply (PPS).
PPS allows for stepwise changes in current and voltage – decreasing the conversion loss during charging, and thereby ensuring that charging is more efficient. Due to more efficient charging, less heat is produced – which increases a battery’s lifespan, and decreases thermal radiation (i.e., heat signature). USB PD together with Programmable Power Supply (PPS) also enables devices to fast-charge over a USB connection.
USB PD brings other benefits, too. The direction of power is not fixed, so you charge a device and at the same time charge the battery pack itself. Knowing the importance of such adaptive fast-charging solutions, Xentris Wireless was the first mobile device company to develop and receive certification for a USB PD device.
As we noted earlier, Soldiers are equipped with a variety of devices that have different voltage requirements (see Figure 1). This is one of the main reasons why Soldiers are therefore burdened with different types of batteries for different devices. In the commercial world however, as the multi-voltage capabilities of USB PD have expanded, Xentris Wireless has developed high capacity, fast-charging solutions that handle everything from 5-volt smartphones and tablets to 20-volt laptops. Radios that require 14-volts can also be supported USB PD and PPS.
The final piece of the USB puzzle was the development of the USB Type-C / USB-C connector. USB-C is designed to replace all previous types with a single reversible connector that can be used to transmit power, data, video, and audio signals with quantum leaps forward in capability.
Reversibility is also one of the key highlights of the USB-C connector that makes it especially user-friendly – this makes the connecting of cables much easier and simpler and brings particular benefits to military applications.
This illustration from the USB-Implementers Forum shows the evolution of USB connectors since 1996.
The STUB Is Born
In July 2020 the Small Tactical Universal Battery (STUB) program was kicked off, and the EXO Charge division of Xentris Wireless began working on the STUB series with a C5ISR team led by Dr. Nathan L. Sharpes.
The STUB series supports adaptive power requirements across multiple device platforms and features a standard interface that allows Soldiers to swap STUBs between devices – eliminating the need for device-specific batteries.
Applications for the STUB series include HF/UHF radios, GPS systems, night vision devices, satellite communication systems, surveillance systems and sensors, ranging and targeting systems, mine detectors and more.
With eight different size/capacity options, as well as multiple attachment methods, all with the same standard connection interface, the STUB delivers unprecedented levels of interoperability for maximum operational flexibility and capability.
The STUB series features rechargeable Lithium-Ion battery packs in 1-cell (1S1P) through 8-cell (4S2P) configuration, with a capacity of 3.5 Ah (xS1P) or 7Ah (xS2P). The STUB series features USB PD (Power Delivery) interface and PPS (Programmable Power Supply) output interface, with VBus and GND output terminals as well as a CC (Communication Channel) terminal – as well as reversible, bi-directional, multi-voltage, power delivery through its USB-C connector.
The available output voltage through PD interface is 5V, 9V, 12V, 15V and 20V. The available output voltage through 1S1P PPS interface is 3.3V and 11V. Maximum discharge current depends on output voltage and battery pack configuration and can be as low as 750 mA or as high as 5A.
STUBs are charged using the USB PD interface. A charging voltage is applied to the PD connection interface using a USB Type-C cable in order to charge, and any USB PD compliant charger can be used to execute fast charging. STUB packs can also be charged using contact terminals (VBus and GND), and adapters for the standard Army chargers (ABC & UBC) are currently in development.
For added practicality and user-friendliness, each STUB model incorporates a unique ‘double-tap’ feature that enables users to check the battery’s State-of-Charge via LED indicators on the top of the battery. This double-tap feature also activates the built-in Power Transfer feature that enables a STUB to transfer its energy to another STUB through a USB-C cable.
The STUB series is now USB-IF certified, is successfully going through MIL-PRF qualification, and has already been certified to MIL-STD-810H and -461G, UN 38.3 and IP68 standards. Delivering unequaled levels of interoperability, commonality, flexibility, and standardization, the STUB family is ready to become the ideal mission-ready power source for next generation tactical electronics.
The EXO Charge division of Xentris Wireless was created specifically to develop rugged power solutions for military applications that leverage advances in commercial technologies. The EXO Charge team is comprised of industry and military veterans with deep experience in both the commercial mobile device market and military dismounted power programs, such as:
- Conformal Wearable Battery (CWB) program of record
- Soldier Worn Integrated Power Equipment System (SWIPES) – the predecessor to Nett Warrior
- Squad Power Manager (SPM) program of record
EXO Charge is leading the next revolution in dismounted Warfighter power with our mission-ready solutions. Visit EXOcharge.com to learn more.