1,721,029 research outputs found
Advantages of retrofitting old electric buses and minibuses
No full textOld electric buses and minibuses equipped with obsolete energy storage systems are today circulating on the roads all over the world. A minibus prototype equipped with Ion-Lithium batteries developed in the ENEA Casaccia Research Centre demonstrated that an old minibus can be retrofitted by replacing the old lead acid batteries pack with a new pack assembled with LiFePO4 electrochemistry. The new batteries provide sufficient power to the electric motor, an amount of energy to cover nearly 30 kilometers with a full charge, with a new battery load of 50% of the previous battery pack. The new technology allows fast charging, thus solving the problem linked due to the long periods requested to charge of the conventional batteries. For example during public transport service, the minibus can be charged with only twenty minutes, allowing such operation at the terminus while waiting for the passengers. A "depleting" strategy can be applied in order to allow the minibus to be operating all the day with several charges at the stops. In this paper, the performance of a retrofitted minibus in comparison with the same minibus equipped with old generation batteries are reported. The economic benefits for the retrofitted minibus in comparison with a new minibus purchased from factories are also reported. © 2017 The Author(s)
Main issues with the design of batteries to power full electric water busses
No full textThis paper presents an analysis of the main issues related to the design of battery pack supplying full electric vessels, such as water busses. After an assessment of the energy storage systems technologies available to power marine applications, battery design aspects are investigated. Hence, a probabilistic battery design method is discussed, taking properly into account the battery lifetime and the inherent economical evaluation. The method is based upon accelerated life tests and allows to face with the randomness of the power load in a suitable way. The optimal size of the battery is determined by tailoring an optimization procedure which ensures the desired robustness against the stochastic load parameters. In the last part of the paper, this probabilistic methodology is applied to a case study represented by a water bus for the public transportation service in the canals of the Venetian lagoon. The numerical results allow to confirm the feasibility and the goodness of the probabilistic approach. © 2016 AEIT
Design considerations for fast AC battery chargers
No full textProliferation of electric vehicles (EVs) is tightly associated to the fast charging of their batteries. Both high-power DC and AC supply options are envisaged for the fast charging of the EV batteries, each of them having different features. This paper considers the AC supply option and deals with the main issues that it poses like an onboard high-power battery charger and its impact on the grid. To face with these issues, a possible arrangement for the battery chargers consists in the integral use of the inverter bound to supply the traction motor and in the proper conditioning of the current absorbed from the grid. In the paper, design considerations for this arrangement are given and applied to the case study of a purely electric, mid-size car. ©2013 WEVA Page
Electrification of off-road vehicles: Examining the feasibility for the Italian market
No full textThe study, made by ENEA in cooperation with the University of Pisa as part of the activities supported by the Italian Ministry of Economic Development in the framework of the Program Agreement for the Research on the Electric System, is related to the situation of Italian market and demonstrates the feasibility of the electrification for off-road vehicles and the possibility to realize it by the means of standard modules. The preliminary dimensioning of the standard modules is also reported, defining the main electric characteristics (voltage and capacity) and the type of chemistry: LiFePO4 is proved to be a very effective solution for this kind of application. The activity goes on towards the final design and the realization of demonstrator units. © 2012 WEVA
Fast charge life cycle test on a lithium-ion battery module
No full textThe paper analyzes the effects of fast charge on a lithium-ion battery module made by 4 lithium-iron-phosphate cells series connected, submitted to a test profile which includes a fast charge step at current rate 3C. This test profile simulates the real working profile requested to the batteries of a electric bus to perform a particular service of local public transportation with recharge of the batteries at the end of line. More than 3,000 shallow cycles were performed: the battery module did not show a significant reduction of performances in terms of capacity and energy, but, on the other side, a relevant increase of the inner resistance was observed. As an effect of this, the autonomy of the electric bus is reduced correspondingly. Fixing a minimum value for the autonomy, a life estimate of the battery module was made. Finally, on the base of this result, a cost estimate and comparison between slow and fast charge was made, under the same service conditions and all through the vehicle life, for a real case of a minibus equipped with a battery system sized for fast charge at the end of line and a larger battery system sized for slow charge at the end of a working day. This comparison proved that, in the case study considered, the solution with fast charge is cheaper and the fast charge can be a valid instrument to solve the problem of short autonomy of electric vehicles. © 2017 MOBI -Mobility, Logistics and Automotive Technology Research Centre
Life cycles test on a lithium battery system
No full textThe topic of the paper is the life cycles test on a lithium battery system 288 V-40 Ah, 11,5 kWh. The test procedure tries to simulate the typical utilization of an electric vehicle: the batteries are discharged by means of a typical profile in urban and suburban context and charged by means of traditional charges and fast charges alternatively. In this way it is possible to simulate the utilization of a driver who uses the electric vehicle and charges the batteries at home (traditional charge) or at a public charging point (quick charge). These tests permit to identify and understand possible problems of the storage system under quick charge and discharge cycles, as well as to define how the performances decrease during the operation. The paper shows the details of the battery system under test, the complete test procedure and the results in terms of reduction of the global performances (life determination as number of cycles) and behavior of the single cells (unbalancing). © 2014 IEEE
Fast charge and local public transport: An Italian experience
No full textThis paper describes the research effort on fast charge, carried out by the PBI project, promoted and funded in the framework of the program 'Industria 2015', by the Italian Ministry for Industry. In more detail, i) describes past experiences and state of art for the public transport sector ii) discusses the Zero-Filobus concept and its application to the PBI project iii) expounds design considerations on an integral AC battery charger for the case study; iiii) describes the high power (150 kW) charging station and the experimentation results. © 2015 IEEE
Design of the battery management system of LiFePO4 batteries for electric off-road vehicles
No full textThis paper describes the design of a modular battery management system for electric off-road vehicles, where lithiumion batteries are expected to be widely used. A massive electrification of off-road vehicles can be enabled by the availability of a standard battery module, provided with an effective management unit. The design and some preliminary experimental results of the module management unit are discussed in this paper. The unit contains a high current active equalizer that enables the dynamic charge equalization among cells and maximizes the usable capacity of the battery. © 2013 IEEE
Design of the Storage System of a High Performance Hybrid Vehicle
No full textWithin the "Industria 2015" Italian framework program, the HI-ZEV project has the aim to develop two high performance vehicles: one full electric and one hybrid. This paper deals with the electric energy storage (EES) design and testing of the hybrid vehicle. A model of the storage system has been developed, simulating each cell like an electric generator with more RC circuits in series. To take account of the heat transfer, a forced convection model has been used with the air speed proportional to the vehicle speed. The model had two calibration steps: the first has determined the electrical parameters of the model (open voltage circuit, internal resistances and capacitors); the second to calibrate the heat transfer model. The first calibration has been made on a climatic chamber at 23 °C discharging one single module with different constant currents from 5C (5 times the nominal capacity) to 25C and charging with currents in the range from 1C to 5C. (where C means the current rate the flow in the battery in 1 hour) The results show that for all the tested cycles the battery pack designed is able to run safely, not exceeding the limit temperature (50°C). The model developed and validated can be a useful tool in the design phase of a battery pack system. © 2015 SAE International
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