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Dual-Voltage Lithium-Ion 6T Batteries for Low-voltage and High-voltage Applications



OBJECTIVE: Dual-voltage Lithium-ion 6T packs (24V/48V) capable of supporting low-voltage and high-voltage ground vehicle and robotic applications. 

DESCRIPTION: The military requires low-voltage 24V batteries to provide energy and power for starting, lighting, & ignition (SLI) and Silent Watch on legacy ground vehicle platforms. There are however current and future military ground vehicle platforms that use or will be using higher voltages ranging from 48V to as high as 600V. Common 48V examples include medium-size military ground robotic platforms, such as the TALON, and 48-V hybrid-electric all-terrain vehicles (ATVs). While the 6T format is widely used in 95% of Army ground vehicles, Lead-Acid and Lithium-ion 6T batteries currently only support 12V and 24V vehicle buses respectively. Therefore, there is a need for a Lithium-ion 6T battery which can support at a minimum 48V operations. To avoid the need for multiple fielded batteries to meet both needs, having a Lithium-ion 6T battery which can support multiple voltages is preferred. Accordingly, innovative solutions must be developed and demonstrated which will allow for a Lithium-ion 6T to operate at both 24V and 48V without greatly increasing cost of the 6T product or affecting its fit and function in legacy 6T applications. Additionally, the higher characteristic voltage of 48V should allow the Lithium-ion 6T to serve as a building block for higher voltage systems up to at least 300V. The Dual-Voltage version of the Lithium-ion 6T in the 24V mode should meet all existing requirements of MIL-PRF-32565. The existing 6T form factor should be maintained to the greatest extent possible, however additional provisions for the higher voltage output are allowable as long as the added components do not increase 6T height beyond post height and do not impede battery tie downs. Technology developed to allow 24V/48V dual-voltage operation should be fully integral to the Lithium-ion 6T battery, with the exception of power output provisions. Technology developed for allowing the Dual-Voltage Lithium-ion 6T to build larger voltage packs (ex: 300V mobility packs) may use external components housed in some type of battery box/enclosure. Technologies developed should additionally allow for achieving 48-V operations using two Dual-Voltage Lithium-Ion 6Ts in 24-V mode in series and using two Dual-Voltage Lithium-ion 6Ts in 48-V mode in parallel. Concepts should also take into account all new required battery electrical and thermal interfaces, battery safety, and battery-to-battery communication requirements to allow for higher voltage operations. 

PHASE I: Identify and determine the engineering, technology, and embedded hardware and software needed to develop this concept. Drawings showing realistic designs based on engineering studies are expected deliverables. Additionally, modeling and simulation to show projected performance and Ah capacity of a single Dual-Voltage Lithium-ion 6T (<5% reduction in overall Li-ion 6T pack capacity to achieve 48-V dual-voltage operation) developed in this phase is expected. Cost analysis projections should also be performed to determine the cost premium between a Standard and Dual-Voltage Lithium-ion 6T (<20% increase in overall Lithium-ion 6T product cost). A bill of materials and volume part costs for the Phase I design should also be developed. This phase also needs to address the challenges identified in the above description, including scaling to larger voltage mobility packs. 

PHASE II: Develop and integrate prototype embedded hardware and software into 24V Lithium-ion 6T's to create Dual-Voltage Li-ion 6Ts capable of both 24V and 48V operations. Additionally, hardware and software should be developed to allow Dual-Voltage Lithium-ion 6Ts in 48V mode to be combined into and demonstrated as a 300V hybrid mobility pack. Analysis should also be performed to show potential for operation up to a 600V pack. Testing should be performed on single Dual-Voltage Li-ion 6T batteries in both the 24V and 48V mode to demonstrate operation, performance, and Ah-capacity (<5% reduction in overall Li-ion 6T pack capacity to achieve 48-V dual-voltage operation). Additionally, 48-V operation should be tested on a 2-series set of two Dual-Voltage Lithium-ion 6T batteries set to 24V mode and on a 2-parallel set of two Dual-Voltage Lithium-ion 6T batteries set to 48V mode. Series operation up to 300V using Dual-Voltage Lithium-ion 6T's in the 48V mode should also be demonstrated. Cost analysis should also be performed on the finalized product to determine the cost premium between a Standard and Dual-Voltage Lithium-ion 6T (<20% increase in overall Lithium-ion 6T product cost). A bill of materials and volume part costs for the Phase II design should also be developed. Deliverables include electrical drawings and technical specifications, software, M&S and test results, and at least six Dual-Voltage Li-ion 6T batteries with the integrated embedded hardware and software improvements as well as software and hardware required to operate the batteries in a 300V hybrid mobility pack configuration. 

PHASE III: This phase will begin installation of Dual-Voltage Lithium-ion 6T packs using the solutions developed in Phase II on selected vehicle platforms (military, commercial EV/HEV, etc.) and will also focus on integration of Phase II embedded hardware and software technologies into the production processes of current Li-ion 6T batteries. 




3:  Kim, Taesic, Wei Qiao, and Liyan Qu. "A series-connected self-reconfigurable multicell battery capable of safe and effective charging/discharging and balancing operations." Applied Power Electronics Conference and Exposition (APEC), 2012 Twenty-Seventh Annual IEEE. IEEE, 2012.

4:  F. Baronti, R. Di Rienzo, N. Papazafiropulos, R. Roncella, "Investigation of series-parallel connections of multi-module batteries for electrified vehicles," Electric Vehicle Conference (IEVC), 2014 IEEE International, pages 1 – 7, 17-19 Dec. 2014.


David Skalny 

(586) 282-2196 

Alexander Hundich 

(586) 282-2289 

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