Browse Topic: Batteries
Current lithium-ion batteries should generally only be charged above 0 °C, as charging below this temperature can promote lithium plating and irreversible degradation. However, conventional pack-level heating elements increase system mass and design complexity. In addition, heat is transferred from outside into the cell, causing the temperature inside the cell to rise slowly. This study evaluates internal Joule heating of cylindrical Li-ion cells using a zero-mean square-wave current excitation and quantifies the associated aging impact. LG INR21700-M50L cells were tested at 0 °C, −10 °C, and −20 °C with three excitation frequencies (50 Hz, 1 Hz, 10 mHz) at 5 A amplitude. Each cycle consisted of 30 min heating followed by 60 min cooling; reference capacity-based state of health (SOH) was assessed every 50 cycles up to 400 cycles. A maximum surface temperature rise of 14.3 K was achieved, with larger temperature rise at lower ambient temperature and lower excitation frequency. Capacity fade remained below approximately 1% for most conditions; however, at −20 °C and 10 mHz a pronounced SOH decrease to 87% was observed, indicating a critical operating regime. The results provide practical guidance for pulse-heating parameter selection and highlight the need for safeguards and further diagnostics in extreme low-frequency excitation at very low temperatures. This heating approach is particularly suitable for simpler battery-electric applications without thermal management, such as e-bikes or power tools. However, it may also be relevant for applications with existing thermal management systems, as it simplifies battery pack design.
This document provides recommendations involving BEV battery data retention and battery design that enhance the potential for BEV battery reuse and serviceability and that can improve recyclability. These recommendations have been developed by a group of professionals skilled in the secondary-use of batteries and in the research, development, and manufacture of BEV batteries and battery systems.
Tire exterior noise has become increasingly critical in vehicle acoustics due to two key developments: updated pass-by noise regulations, which amplify the relative contribution of tire noise, and the rise of Battery Electric Vehicles (BEVs), which lack traditional powertrain noise. Design trends in BEVs—such as increased vehicle mass from battery packs and the widespread use of large-diameter, wide, low-profile tires—further intensify tire noise due to stiffer constructions and altered contact dynamics. A common method for predicting tire noise is the source-transfer-receiver model, where the tire is represented by a set of monopoles with volume velocity Q derived from near-field measurements. Acoustic propagation is modeled via p/Q transfer functions. Despite its simplifications, this approach is practical for vehicle development, enabling clear separation between source and transfer mechanisms and facilitating targeted noise control strategies. In previous work, we proposed a rigorous framework to optimize both the spatial distribution and strength of the monopole sources. Positions were identified using an L1-norm regularization via the Lasso algorithm, promoting sparsity and physical interpretability. Strengths were estimated using an L2-norm Tikhonov regularization, which stabilizes the solution against measurement noise. While the Tikhonov regularization parameter was previously tuned manually through trial and error, we now enhance predictive accuracy by selecting it via a cross-validation technique, ensuring a more robust and data-driven optimization. Besides this, compared to the previous work the approach here is validated for the prediction of both indoor and outdoor pass-by noise, as well as for multiple tire types providing different noise levels. Results demonstrate the method’s robustness, accuracy, and applicability for acoustic development in modern vehicle platforms.
Harbinger revealed its HC Series Cab during Work Truck Week 2026 in Indianapolis, Indiana. The HC Series is a new line of medium-duty, low cab forward vehicles available as both an electric and plug-in hybrid model. Harbinger states that the HC Series' hybrid powertrain uses a range-extended hybrid platform with a gasoline engine to recharge the truck's batteries, extending range up to 500 miles (805 km), depending on upfit configuration and drive cycle.
With new energy vehicles developing rapidly, battery safety, as an important part of the impact on the range of new energy vehicles and vehicle safety, has become the focus of attention. The battery pack protection plate is a core component to protect the battery, its performance needs not only impact resistance, but also lightweight, honeycomb sandwich structure with its excellent energy absorption characteristics and weight reduction performance by the battery pack protection plate performance research. At present, the core-to-face sheet interaction in conventional sandwich structures subjected to impact loads has not been fully elucidated, and the quantitative characterization of damage is insufficient, so this paper aims to optimize the lightweight impact-resistant structure by exploring the synergistic energy dissipation mechanism between the high-strength core material and the steel plate. The study combines theory and simulation, adopting ideal rigid-plastic film theory to establish a critical response model to predict the structural failure threshold, equivalent single-layer theory to simplify the analysis of plywood, and a stiffness matrix model to quantify the structural mechanical contribution of each layer. A two-material synergistic design framework is proposed by fully considering the material properties and adopting the corresponding intrinsic structure and failure criteria for different materials. Analysis reveals that geometric confinement is a key characteristic of the honeycomb sandwich panel’s response and a strain gradient driving mechanism at low impact resistance, and a new energy distribution paradigm is found through the analysis of the energy absorption ratio. The theoretical and simulation results are in great agreement with each other, which just has a difference of 0.7% in the peak force, 1.4% in the critical displacement error, and less than 2% in the impulse integration error. The proposed dual-material co-design framework provides a solution for electric vehicle battery protection systems that balances lightweight and impact resistance.
Bird accidental collision with overhead transmission lines poses a threat to the ecology of rare bird populations. This article analyzes the warning measures to prevent birds from accidental collisions at home and abroad. In response to the low efficiency of manual installation and the poor static warning effect in preventing birds from accidental collisions with overhead transmission lines, the visual characteristics of birds are analyzed. A drone-based automatic installation flash-type bird accidental collision warning device is proposed, which includes a fixture, a disc, and a luminous circuit. The fixture can be carried and installed on the overhead line by a drone and can be easily disassembled. The disc adopts eye-catching colors and has a hollow structure to reduce wind resistance load. The luminous circuit includes solar panels, charge and discharge control circuits, flicker control circuits, batteries, and luminous components. The drone suspension warning device test was conducted, and the results showed that the device can be easily suspended from the overhead line by the drone.
Electric vertical takeoff and landing aircraft impose significantly higher electrochemical and thermal demands on Li-ion batteries than conventional electric vehicles, yet publicly available aging datasets for this application remain limited in applicability, cell technology, and statistical robustness. This study experimentally characterizes the degradation behavior of state-of-the-art Molicel P45B 21700 cells under realistic Urban Air Mobility operating conditions involving high power demand, rapid turnaround, and repeated cycling. Eight cells are subjected to over 3,000 cycles using a fast constant-current charging protocol and a multi-segment constant-power discharge profile. The discharge profile is derived from a representative 7000-lb winged eVTOL with a 20-mile range, requiring normalized power rates of 6.4E during takeoff and landing and 1.6E during cruise. Periodic Reference Performance Tests are conducted to track capacity fade, internal resistance evolution, and energy efficiency. The cells retained over 90% of their initial capacity after 3,270 cycles, while total energy efficiency remained stable at 91%, comprising impedance and hysteresis-driven components of approximately 94% and 97%, respectively. Direct current internal resistance exhibited an initial decrease before stabilizing, yet total discharged capacity increased from 1.81 Ah to 1.84 Ah, indicating aging-driven polarization effects not captured by DCIR. A zero-order equivalent circuit model underpredicts discharged capacity by approximately 4% for fresh cells, increasing to nearly 6% at cycle 3,270 due to unmodeled time-dependent polarization effects. These results demonstrate that while modern Li-ion cells exhibit strong durability under repetitive high-power usage, the accuracy of battery performance prediction is strongly dependent on dynamic impedance effects beyond conventional DCIR-based models.
The current work presents a methodology to estimate the mission and performance capabilities of a generic rotorcraft configuration, to satisfy the need of evaluating the integration of a full electric powertrain in the aircraft design. To include all the design steps, two different approaches are proposed. For the preliminary phase, the "Analytic Method" is considered, which exploits a purely resistive model. Conversely, a method based on look-up tables called "Table Method" is intended to be used in more advanced phase, when the battery pack is defined. Both approaches are tested by evaluating a reference mission and a hover chart. Finally, a verification of the presented methodology is carried out by comparing the mission results with a commercial software, specialized in the evaluation of the cell discharge when a given power spectrum is provided.
A single pilot, full-scale, proton exchange membrane fuel cell powered helicopter is flight tested with 700 bar compressed gaseous hydrogen as fuel. Models are developed for the fuel cell, hydrogen and the helicopter and validated with flight test data. The data covers powerplant architecture, stack electrical characteristics, hydrogen flow, detailed component weights, radiator drag, and full aircraft power measured in hover and forward fight. The validated models are then used to conceptually explore the conversion of a larger, more capable, turbine engine Robinson R66-like airframe with liquid hydrogen supplied fuel cell. Predictions indicate that payloads of 300−600 lb can be carried over a range of 200 nautical miles with current fuel cell technology if hydrogen storage weight fractions of 0.2−0.3 can be achieved and the tank and baggage compartment both are used for fuel. The key conclusion is that hydrogen fuel cell helicopters are feasible and the test data and validations presented here open the door for advancing its performance in the future.
This paper explores the potential of three different hybridization solutions for a medium-sized rotorcraft: an electric tail rotor, an "eco-mode", and a "boost-mode". The solutions were evaluated as a retrofit to a generalized medium lift rotorcraft and the impact on performance across five mission types, representative of the typical use cases for a military rotorcraft, was assessed. Two separate rotorcraft performance modelling tools were used to carry out the assessment, allowing for the results to be cross-examined. The models predicted performance gains for the eco-mode configuration when utilizing the single engine cruise capability for low-speed applications. Likewise, the models predicted improved performance for the boost-mode configuration when operating at hot and high (6,000 ft, 95°F) conditions due to the increased power provided by the battery system. However, all three solutions suffered from increased platform empty weight which negatively impacted performance at certain flight states.
Electric Vertical Take-Off and Landing (eVTOL) aircraft are poised to transform urban and regional mobility by offering zero-emission, congestion-free transportation. As regulatory frameworks evolve and advanced air mobility (AAM) gains traction, manufacturers are exploring propulsion strategies that improve range, power delivery, and overall system efficiency. A key challenge in eVTOL development is balancing range with payload capacity. While larger battery packs can extend range, they also increase system weight, reduce payload, and prolong charging times, limiting operational flexibility and turnaround time. Hydrogen fuel cells, supported by liquid hydrogen (LH₂) present a promising alternative for eVTOL propulsion. This study proposes a methodology for optimizing fuel cell propulsion systems tailored to eVTOL applications. A multi-physics modeling framework for eVTOL flight dynamics and propulsion system was developed, representing the target eVTOL configuration. For a defined flight path including vertical takeoff, hover, cruise, and landing, a Genetic Algorithm (GA) based optimization was conducted on propulsion system. The algorithm down-selected battery size, fuel cell stack specifications, and hydrogen tank capacity to meet mission requirements while minimizing propulsion system weight. The modeling framework was also used to evaluate trade-offs between payload and performance as functions of component sizing, battery chemistry and energy distribution strategy.
This paper demonstrates the sizing and optimization of a hybrid-electric multi-tilt rotor configuration of both conventional and vertical takeoff and landing capabilities. The study uses Parametric Energy-Based Aircraft Configuration Evaluator to design and optimize the aircraft. To explore the design space comprising both discrete and continuous design variables, a genetic algorithm is used for optimization. The design variables are not limited to conventional aero-propulsive parameters such as wing loading, aspect ratio, and disk loading. Battery-related parameters such as the maximum permissible depth of discharge, maximum permissible discharge rate, and the number of parallel strings in a battery pack are also considered in this work to study their impact on aircraft gross weight and fuel consumption. The Non-dominated Sorting Genetic Algorithm-II (NSGA-II) optimization framework is used to solve the multi-objective optimization problem, with objectives to minimize the maximum take-off mass and fuel weight. The sensitivity studies showed that higher wing-loading and lower-aspect-ratio designs resulted in lower gross weight. A higher permissible depth of discharge led to lower fuel consumption, despite a slight increase in gross weight. But increasing the number of parallel strings in a battery pack increased gross weight with negligible change in fuel consumption.
This study evaluates the impact of range extension on gross takeoff weight (GTOW) and energy cost for the NASA Lift+Cruise eVTOL configuration under present and near-term battery technology limitations. A baseline 8,210 lb, 6-passenger vehicle, originally designed for a 75-mile mission at 400 Wh/kg battery energy density, is shown to achieve only 15 miles at a more realistic 200 Wh/kg, largely due to the 20-minute SFAR reserve, which accounts for 64% of total onboard energy. To quantify the penalties of range extension, three sizing strategies are examined: fixed GTOW with payload trade-offs, fixed-geometry overloading, and fully co-scaled vehicle resizing. The co-scaled configurations reveal a strong nonlinear GTOW growth driven by an "adding battery to carry battery" effect, in which increases in GTOW necessitate heavier structure and propulsion, leading to a practical feasibility ceiling near 45 miles. Energy cost per payload-mile is found to be non-monotonic, reaching a minimum near 20-25 miles before increasing due to compounding weight penalties, contrary to trends predicted by fixed-weight analyses. Significant off-design penalties are also observed; operating a 40-mile aircraft on a 10-mile mission incurs a 72% energy cost increase relative to a co-scaled vehicle for 10 miles. Increasing battery energy density by 22.5% (to 245 Wh/kg) reduces the 6-passenger 40-mile design GTOW by 33% (from 13,712 lb to 9,187 lb) and shifts the optimal energy cost point outward to 30 miles. Ultimately, battery energy density is identified as the dominant parameter dictating the vehicle size, weight, performance, and the fundamental operational feasibility of UAM eVTOLs.
The present work focuses on the sizing and analysis of a parallel hybrid propulsion architecture for a conventional rotary light Unmanned Aerial Vehicle (UAV) in the 200kg class. First, the design methodology is outlined, with an emphasis on the optimization of the battery pack, which is one of the most crucial component of the whole powertrain. The sizing approach is applied to a wide range of thermal and electric power ratios, as well as two distinct hybridization strategies, to investigate the broad design space and discover possible sweet spots. For this aim, the various design points are then evaluated in terms of impact on aircraft capabilities, considering both extensive and intensive performance. Hence, the results provide the main advantages and disadvantages, performance wise, of the hybrid propulsion in comparison to a conventional full thermal solution.
From material selection to system-level performance Transportation's shift toward electric power - whether cars, planes, or big trucks - has made battery engineering a pretty wild, multidisciplinary puzzle. It's not just about coming up with a prototype anymore. To hit the right mix of energy density, power, safety, cost, and longevity, teams need to rethink how they design these systems. Enter simulation and modeling tools. Engineers now use these digital tools to blend electrochemistry, thermal management, materials science, and whole-system design. Instead of jumping straight to building, they try out battery ideas in the virtual world first, speeding up how long it takes to figure out what works and what doesn't and boosting the reliability of those batteries in the real world. Today, battery simulation spans multiple scales from the behavior of active materials within electrodes to the thermal dynamics of the entire battery pack as integrated into a vehicle.
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