Browse Topic: Nickel-metal hydride batteries
Electrification is a pillar of Lexus's “next chapter.” The fifth-generation Lexus RX progresses this objective, offering four new powertrains including a high-performance hybrid and the company's first-ever plug-in hybrid (PHEV) - though the latter is not available in the U.S. at launch. Other “foundational elements” include bold design, intuitive technology and Lexus driving signature. Experienced first-hand by SAE Media on the hilly, twisty terrain north and west of Santa Barbara, the 2023 RX, which rides on the lighter, stiffer GA-K platform that also underpins the smaller Lexus NX, hits on all marks.
This document contains definitions currently used in the automotive industry as they relate to energy storage and batteries for starting, lighting, and ignition applications, as well as for hybrid electric vehicles (HEV) and electric vehicles (EVs). It is intended that this document be a resource for those writing other battery, HEV, and EV documents, specifications, standards, or recommended practices. The use of the term “battery” in this document can be assumed to be a rechargeable battery (secondary battery). The terminology may be applied to other industries if desired.
This SAE Recommended Practice provides for common test and verification methods to determine lead acid and nickel metal hydride electric vehicle battery module performance. The document creates the necessary performance tests to determine (a) what the basic performance of EV battery modules is, and (b) if battery modules meet minimum performance specification established by vehicle manufacturers or other purchasers. Specific values for these minimum performance specifications are not a part of this document.
This paper presents a technical, financial and environmental analysis of four different hybrid buses operated under Buenos Aires driving conditions. A conventional diesel bus is used as reference and three electric hybrids equipped with different energy storage technologies, Li-Ion, NiMH batteries and double layer capacitors (ultracapacitors), are evaluated, along with a hydraulic hybrid platform which uses high-pressure accumulators as its energy buffer. The operating conditions of the buses are set using real driving GPS data collected from various bus routes within the city. The different vehicle platforms are modeled on AUTONOMIE SA and validated by comparing the obtained fuel consumption results to those reported by local transport authorities and values found in the literature. The embedded energy and CO2 emissions of each platform are estimated using GREET and the total cost of ownership of each vehicle is calculated and compared to that of the conventional bus. Furthermore, aging models are proposed to evaluate the life duration of the batteries and ultracapacitors. Results show that, independent of the energy storage technology, the fuel economy performance of all hybrids is highly dependent on the size and configuration of the powertrain and energy storage components. When optimized, all hybrids achieve significant fuel consumption reductions compared to a conventional diesel bus, however, the ultracapacitor based system seems to outperform the other technologies. The battery based electric buses achieve similar fuel consumption reductions, but the NiMH based batteries shows a considerably shorter life expectancy. This has a significant impact on both the economic and environmental performance of this vehicle. The life cycle emission analysis shows that, given the high fuel consumption of a conventional bus, the additional embedded CO2 emissions of the hybrid vehicles are offseted by the achieved reduction of in-service CO2 emissions due to fuel consumption reductions. Regarding the economic performance of the different platforms, results show that the fuel savings achieved by all hybrids displace the higher capital costs required. Overall, all hybrid buses show a strong potential to reduce both CO2 emissions and costs, resulting in negative costs of CO2 abatement.
The analysis of nickel metal hydride (Ni-MH) battery performance is very important for automotive researchers and manufacturers. The performance of a battery can be described as a direct consequence of various chemical and physical phenomena taking place inside the container. In this paper, a physics-based model of a Ni-MH battery will be presented. To analyze its performance, the efficiency of the battery is chosen as the performance measure, which is defined as the ratio of the energy output from the battery and the energy input to the battery while charging. Parametric sensitivity analysis will be used to generate sensitivity information for the state variables of the model. The generated information will be used to showcase how sensitivity information can be used to identify unique model behavior and how it can be used to optimize the capacity of the battery. The results will be validated using a finite difference formulation.
The analysis of nickel metal hydride (Ni-MH) battery performance is very important for automotive researchers and manufacturers. The performance of a battery can be described as a direct consequence of various chemical and physical phenomena taking place inside the container. In this paper, a physics-based model of a Ni-MH battery will be presented. To analyze its performance, the efficiency of the battery is chosen as the performance measure, which is defined as the ratio of the energy output from the battery and the energy input to the battery while charging. Parametric sensitivity analysis will be used to generate sensitivity information for the state variables of the model. The generated information will be used to showcase how sensitivity information can be used to identify unique model behavior and how it can be used to optimize the capacity of the battery. The results will be validated using a finite difference formulation.
The Toyota Prius battery pack consists of 38 individual battery modules, each module contains 6 NiMH cells in series. This means that each pack contains 228 NiMH cells. Each cell has the potential to fail. This report investigates the mode of failure of Prius battery packs by first analysing a number of packs in the lab, and then road testing them in a Toyota Prius. The analysis of the battery packs show that some packs had aged “linearly”, that is in a balanced manner, such that the state of health of all modules remained similar. However, in other packs discrete modules had significantly different states of health. A pack that consists of cells that are matched in both state of health and state of charge delivers the best performance. The research also showed that the worst cell in the pack determines the overall pack performance. This was demonstrated by substituting reduced capacity or short-circuited modules into a functioning battery pack. A vehicle with a pack consisting of 37 2400 mAh battery modules and one 1200 mAh battery module was only able to drive 1.3 km in Electric Vehicle mode, as opposed to 2.6 km with a pack consisting of 38 2400 mAh battery modules.
The central performance requirement for electrochemical energy storage systems for the full power-assist hybrid electric vehicle (HEV) is pulse power capability, typically 25-40 kW pulse power capability for 10 seconds duration. Standard test procedures utilize constant current pulses. However, in the HEV application, the power transient for acceleration is a ramped power transient and the power transient for regenerative braking power is a descending power ramp. This paper compares the usable power capability of batteries and supercapacitors under constant current, constant power, and ramped power transients. Although the usable battery discharge power is relatively insensitive to the transient type applied, 10-40% higher regenerative braking charge capability is observed with ramped power transients. With supercapacitors, the discharge and charge capability is much more strongly dependent on the type of power transient. The discharge power capability in a ramped power transient is 2.4 times that in a constant current pulse. The regen charge power capability is over 3 times that in a constant current pulse. Standard constant current test procedures thus underestimate the power capability of supercapacitors for HEV applications by several-fold. Supercapacitors provided over 2500 W/kg usable power for HEV applications, exceeding that of high power nickel metal hydride and lithium ion batteries tested.
Rare earths are a group of elements whose availability has been of concern due to monopolistic supply conditions and environmentally unsustainable mining practices. To evaluate the risks of rare earths availability to automakers, a first step is to determine raw material content and value in vehicles. This task is challenging because rare earth elements are used in small quantities, in a large number of components, and by suppliers far upstream in the supply chain. For this work, data on rare earth content reported by vehicle parts suppliers was assessed to estimate the rare earth usage of a typical conventional gasoline engine midsize sedan and a full hybrid sedan. Parts were selected from a large set of reported parts to build a hypothetical typical mid-size sedan. Estimates of rare earth content for vehicles with alternative powertrain and battery technologies were made based on the available parts' data. We estimate that approximately 0.44 kg of rare earths are used in a typical conventional sedan, with approximately 80% of the rare earth content in magnets. As such, neodymium is the most extensively used rare earth, followed by cerium, which is used mainly in catalytic converters. The mass of rare earths in a full hybrid electric vehicle with a nickel metal hydride battery is approximately 4.5 kg. A full hybrid electric vehicle with a lithium-ion battery contains approximately 1 kg of rare earth elements. Future plug-in hybrid electric and battery electric vehicles are expected to be equipped with lithium-ion batteries and have rare earth contents that still need to be evaluated.
Lithium-ion batteries have higher energy content and power density than Nickel-metal hydride (NiMH) batteries, but require carefully management for durability and safety. Unlike NiMH batteries, which are controlled on a battery unit basis, each lithium-ion cell generates a different voltage. Typically, the complex controllers required to equalize individual cell voltages are large and costly. We have developed a low-cost battery monitoring unit that performs the same function with a proprietary cell-voltage equalizing system. This new unit also offers various innovative technologies, such as detecting overcharge and over-discharge, fault diagnosis and the measurement of the batteries internal resistance to monitor degradation.
Technologies related to electrical systems for the 2011 hybrid model have been developed. In order to increase energy recovery during driving, improvements were made compared to the 2006 model in terms of motor output increase and high-efficiency range expansion. In consideration of vehicle control associated with the use of lithium-ion batteries (LIBs) as well as reliability, a system to control effective use of battery performance was developed which involves detection of battery conditions. Control of energy management was optimized compared to nickel metal hydride (NiMH) batteries through the use of higher-output LIBs and a high-output motor.
Technologies related to electrical systems for the 2011 hybrid model have been developed. In order to increase energy recovery during driving, improvements were made compared to the 2006 model in terms of motor output increase and high-efficiency range expansion, and considerations were also given to motor NV (noise and vibration). In consideration of vehicle control associated with the use of lithium-ion batteries (LIBs) as well as reliability, a system to control effective use of battery performance was developed which involves detection of battery conditions. Control of energy management was optimized compared to nickel metal hydride (NiMH) batteries through the use of higher-output LIBs and a high-output motor.
Because of its widespread use in almost all the current electric and hybrid electric vehicles on the market, nickel metal hydride (Ni-MH) battery performance is very important for automotive researchers and manufacturers. The performance of a battery can be described as a direct consequence of various chemical and physical phenomena taking place inside the container. To help understand these complex phenomena, a mathematical model of a Ni-MH battery will be presented in this paper. A parametric importance analysis is performed on this model to assess the contribution of individual model parameters to the battery performance. In this paper the efficiency of the battery is chosen as the performance measure. Efficiency is defined by the ratio of the energy output from the battery and the energy input to the battery while charging. By evaluating the sensitivity of the efficiency with respect to various model parameters, the order of importance of those parameters is obtained. In this analysis, the efficiency of the battery is found to be most sensitive to the ambient temperature and the surface density of the active nickel hydroxide.
MISSISSIPPI STATE UNIVERSITY STUDENTS DESIGNED AND FABRICATED AWARD-WINNING HYBRID-ELECTRIC VEHICLES WITH SUPPORT FROM INDUSTRIAL MENTORS. FOR THE PAST 21 YEARS, Advanced Vehicle Technology Competitions (AVTCs) sponsored by the U.S. Department of Energy have challenged engineering students to develop vehicles using cutting-edge technologies that yield improved fuel economy and reduced emissions. The automotive industry has benefited from graduates who are prepared to almost immediately contribute once they begin employment as well as by their innovative concepts that have resulted from their imagination and fascination with the automobile. For the educational institution, the competitions have promoted a project-based pedagogy that has proven to be effective for motivating and enriching the educational experience of many students. Engineering students from Mississippi State University participated in the Challenge X vehicle competition and are now engaged in EcoCAR. Both of these multi-year collegiate AVTCs were also sponsored by General Motors and Natural Resources Canada as well as several automotive-related industries. The Mississippi State students have been particularly adept at designing and constructing hybrid vehicles, as they have emerged as the Challenge X national winner and last May were again successful as they competed with their extended-range electric vehicle at the GM Proving Grounds in Yuma, AZ. This was followed by technical and outreach presentations descriptive of their winning vehicle that the students delivered in San Diego.
Lithium-ion (Li-ion) batteries are becoming widely used high-energy sources and a replacement of the Nickel Metal Hydride batteries in electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV). Because of their light weight and high energy density, Li-ion cells can significantly reduce the weight and volume of the battery packs for EVs, HEVs and PHEVs. Some materials in the Li-ion cells have low thermal stabilities and they may become thermally unstable when their working temperature becomes higher than the upper limit of allowed operating temperature range. Thus, the cell working temperature has a significant impact on the life of Li-ion batteries. A proper control of the cell working temperature is crucial to the safety of the battery system and improving the battery life. This paper outlines an approach for the thermal analysis of Li-ion battery cells and modules. The thermal behavior was analyzed of a commercially available A123 Hymotion™ L5 PCM pack assembled with the A123-26650 Li-ion cylindrical cells using the electro-thermal finite element model developed in this paper. The simulation results showed good agreement with measurements. This demonstrates that the electro-thermal finite element model developed in this study can reasonably characterize the thermal behavior of a battery pack. Although only cylindrical cells are analyzed, the method for characterizing the thermal behavior of the Li-ion battery cells developed in this study can also be applied to battery cells with other geometries, such as prismatic and pouch cells.
ABSTRACT In this session, PowerGenix Director of Application Development Todd Tatar will describe the nickel-zinc (NiZn) technical solution, the properties and benefits of NiZn batteries, potential advantages of NiZn batteries in military ground vehicles, and a switching battery management solution to parallel batteries for extended power.
Lithium battery technology is finally making its way to production hybrids and planned EVs, but improvements are needed. While many forecasted “future” technologies seem to continuously retreat into the future, perpetually out of reach, lithium-ion (Li-ion) battery technology for use in hybrid, plug-in hybrid, and pure battery-electric vehicles is maturing on schedule and will soon play a key role in the growth of electric-drive-vehicle sales. With the Mercedes-Benz S400 hybrid, Li-ion battery technology has reached mass production. Li-ion batteries also are used in the limited-production Tesla Roadster. Today, the nascent market for Li-ion batteries for transportation use is $31.9 million, according to market researcher A.T. Kearney. That market will balloon to $21.8 billion-with a “b”-by 2015 and continue to $74.1 billion by 2020, the company predicts.
Siemens presentation of "Experiences of the Hybrid Energy Storage System Sitras HES based on a NiMH-battery and Double Layer Capacitors in Tram Operation" at Advanced Automotive Battery Conference
Based on our extensive experience and data derived from manufacturing large quantities of various cell sizes and chemistries, we are here to present our findings and reasons for selecting NiMH and Lithium Iron Phosphate as our preferred choice for EV/HEV applications, and a comparison of different chemistries.In summary, EVB Technology’s position on the practical choice of batteries for EVs and HEVs: NiMH is the most practical choice for batteries in EVs and HEVs today, and Lithium Iron Phosphate will be our focus for future development and applications.
The transition from nickel metal-hydride (NiMH) battery technology to lithium ion (Li-Ion) battery technology in hybrid electric vehicle applications presents both new opportunities and new challenges for vehicle implementation. Full recognition and acceptance of these opportunities and challenges is necessary for the vehicle manufacturer to efficiently proceed towards production implementation of Li-Ion battery technology in hybrid electric vehicles, even for those vehicle manufacturers who are already fully experienced with the significant prerequisite of NiMH battery technology implementation in vehicle applications. In this paper, potential opportunities and advantages for the vehicle manufacturer in areas including reduced width of the system operating voltage window, control algorithm and SOC determination simplification, improved energy efficiency, reduced heat generation, increased long-term stand capability, cell venting considerations, and reduced system weight, etc, will be discussed and quantified. Correspondingly, potential challenges for the vehicle manufacturer will be examined in areas including incorporation of abuse tolerant functionality, design validation implications, and recycling, etc.
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