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Intelligent Lithium-ion 6T MIL-PRF-32565 Compliant Battery Maintenance & Charging System



OBJECTIVE: An advanced, intelligent Lithium-ion 6T MIL-PRF-32565 Compliant Battery Maintenance & Charging System. 

DESCRIPTION: The 28-V Lithium-ion 6T drop-in replacement battery (Li-ion 6T) is a critical technology to enhance energy storage to improve warfighting performance across the Army, Marines, and Navy. The Li-ion 6T is a drop-in replacement for legacy Lead-Acid 6T batteries for starting, lighting, and ignition (SLI) and silent-watch applications, and provides the same form, fit, and expanded function, including increased silent watch time, significantly extended cycle life, and faster recharge time. Currently fielded Lead-Acid 6TAGM battery chargers and maintenance equipment have limited or no compatibility with Li-ion 6T batteries, in part due to differences in battery chemistry and voltage levels (12V vs. 24V). Additionally, fielded charger solutions for Lead-Acid typically lack sophistication in charging method, usually only providing different preset charging voltage levels, and do not provide enhanced prognostics/diagnostics or CAN communication required for interfacing with modern, smart batteries. Accordingly, an intelligent Li-ion 6T MIL-PRF-32565 Compliant Battery Maintenance & Charging System (hereafter referred to just as “charger”) is required to improve the field supportability, charging, and maintenance of Li-ion 6T batteries as well as to enable enhanced capabilities such as optimized charging per battery vendor/type, optimized charging for a given vehicle/mission, discharging to a preset SOC for storage & transport, advanced prognostics/diagnostics, detection of faults & manufacturing defects, bi-directional battery-to-charger CAN communication, equalization, and updating battery firmware over CAN bus (MIL-PRF-32565 Sections, A.5.3). Technology developed should be compatible with all MIL-PRF-32565 compliant Li-ion 6T products and generally applicable to low-voltage commercial Li-ion battery packs. The technology shall also aide the user in selection of optimal sets of Li-ion 6T batteries for a given vehicle platform and mission as well as identify deficit batteries or batteries in need of replacement. The technology shall be capable of optimally charging Li-ion 6T batteries individually as well as in full vehicle sets of up to six Li-ion 6Ts. The charger shall be MIL-STD-1275 compliant, shall support charging/discharging of both Type I and Type II batteries, and shall allow for bi-directional transfer of power between batteries for high efficiency and reducing losses. The charger shall be military ruggedized, designed for operation over the entire military temperature range, and include a human interface (graphical) that considers human factors. The charger shall be capable of providing external power to the battery’s BMS through the battery power terminals (3.6.2). In support of prognostics, the charger shall additionally verify functionality of battery safety protections ( as well as the resolution/error of the performance characteristics of MIL-PRF-32565 Table IV. The Phase II chargers shall additionally be capable of receiving and transmitting all messages and signals required to communicate with the battery in Appendix A of MIL-PRF-32565 and shall meet the requirements of SAE J1939 and ISO 11898, while providing variable baud rates and termination resistances where necessary. The charger shall interface with the MIL-DTL-38999 receptacle on the Li-ion 6T battery. 

PHASE I: Identify and determine the engineering, technology, and hardware and software needed to develop this concept. Additionally, sophisticated novel charging/discharging techniques & methods should also be developed in this Phase to be employed in Phase II to achieve standard and rapid charging (4.4.9, while producing the most benign impact to cycle life and supporting a range of turnaround times as the mission requires. These techniques & methods should make use of relevant parameters transmitted by the smart battery and should be adapted as necessary to optimize charge, discharge, and equalization for a given battery vendor, type, and chemistry. Bench top testing of a Phase I embedded hardware and software charger prototype for one Li-ion 6T battery is expected. Drawings showing realistic designs based on engineering studies are expected deliverables. Additionally, modeling and simulation (M&S) tools needed to drive the technology is expected. A bill of materials and volume part costs for the Phase I designs should also be developed. Designs in this phase also need to address the challenges and requirements identified in the above description as well as the charger requirements of Phase II. 

PHASE II: Develop and integrate prototype hardware and software into intelligent Li-ion 6T MIL-PRF-32565 Compliant Battery Maintenance & Charging Systems (Phase II chargers) using the designs and technologies developed in Phase I. The technology shall be designed such that it is generally applicable to all MIL-PRF-compliant Li-ion 6T batteries (and low-voltage Li-ion batteries generally), but must be tested and demonstrated on at least two different Li-ion 6T battery variants. The chargers shall accommodate a variety of input source voltages (ex: 120/208/240VAC single/three phase, 20-60 VDC), including connection to a Tactical Quiet Generator (TQG). Deliverables shall include electrical drawings and technical specifications, software, M&S and test results, and at least two Phase II chargers, each capable of charging at least six batteries. The Phase II chargers shall include the ability to (1) read and use manufacturer specific parameters for charge/discharge optimization; (2) set battery baud rates (A.3.3.5); (3) capture and log long-term fault data (3.6.8) and short-term fault data (3.6.9) for reporting and improving the chargers’ Li-ion 6T prognostics/diagnostics; (4) check the hardware and software version of the battery (; (5) execute built-in test; (6) read and reset DTC trouble code faults and failures (; (7) perform configuration overwrite (A.5.5); (8) set the transportability command, SOC reserve limit, application overcurrent limits, and application overcurrent periods (A.5.7.1-3); and (9) read in the maximum charge current and bus voltage request signals for optimization of charging functions (, The charger shall be capable of control of battery state transitions through CAN commands and charger output connections, including Operation, Standby, Maintenance, Protected, and Dormant State (3.6.6). The charger shall be capable of powering and controlling via CAN (enabling/disabling) the battery’s internal automatic heater function to allow heating of the battery to the temperature required for optimum charging for a given set of charge conditions ( The charger shall be capable of altering the state of the battery contactor via CAN bus ( The charger shall be capable of mimicking the master power switch (On and Off states) and reset pin as well as acting as a virtual master power switch (A., A.3.3.7). The charger shall be capable of placing the battery into battle override mode (3.3.6) to allow for repair of faults that can be safely corrected through charge/discharge operations. A bill of materials and volume part costs for the Phase II design should also be developed. 

PHASE III: This phase will begin installation and integration of the solutions developed in Phase II into military grade Li-ion 6T chargers as well as commercial low-voltage Li-ion chargers. 


1: Seo, Minhwan, et al. "Detection Method for Soft Internal Short Circuit in Lithium-Ion Battery Pack by Extracting Open Circuit Voltage of Faulted Cell." Energies (19961073) 11.7 (2018).

KEYWORDS: Lithium-ion, 6T, Charger, CAN Bus, Batteries, Power, Energy, Maintenance 

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