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[en] This paper estimates the charging demand of an early electric vehicle (EV) market in Beijing and proposes an assignment model to distribute charging infrastructure. It finds that each type of charging infrastructure has its limitation, and integration is needed to offer a reliable charging service. It also reveals that the service radius of fast charging stations directly influences the final distribution pattern and an infrastructure deployment strategy with short service radius for fast charging stations has relatively fewer disturbances on the power grid. Additionally, although the adoption of electric vehicles will cause an additional electrical load on the Beijing's power grid, this additional load can be accommodated by the current grid's capacity via the charging time management and the battery swap strategy. - Highlight: ► Charging posts, fast charging stations, and battery swap stations should be integrated. ► Charging posts at home parking places will take a major role in a charging network. ► A service radius of 2 km is proposed for fast charging stations deployment. ► The additional charging load from EVs can be accommodated by charging time management.
[en] Complete text of publication follows. The miners' headlamp combines a battery pack for waistbelt mounting with a detachable headlamp/cable unit. The battery that incorporates the Ni/Cd 'gel-cells' and the KOH electrolyte (which acts only as an ion conductor and does not contribute significantly to the cell's reaction) is the most important piece of the lamp. The total reaction of the NiCd cell is: 2NiOOH + 2H2O + Cd ↔ 2Ni(OH)2 + Cd(OH)2 The preferred charging regime for caplamps is top-up charging with an occasional full discharge cycle. Nickel-cadmium cells are charged by applying direct current with the proper polarity to the cell. That means the charger will deliver a constant amount of current to the battery regardless of its voltage. During the first 70% of the charge cycle, a NiCd battery absorbs almost all of the energy and the battery remains cool. After the 70% charge threshold is reached, less and less energy is absorbed. The cells start to generate excess gases the pressure rises and the temperature increases. The charge acceptance drops further and once full charge is reached, the battery goes into overcharge. The higher the overcharge rate the higher the rate of gas generation. The battery made up of three NiCd cells has the potential for cell reversal problems when the discharge is deep enough to bring one or more of the cells in a battery to zero voltage. If discharge continues beyond this point, the voltage on the depleted cell will reverse polarity. The problem that occurs is the generation of hydrogen gas. As the electrodes change polarity they will generate hydrogen. Since the hydrogen will not recombine, the internal cell pressure will build up to a level that causes the cell to vent if the reverse charge current is maintained for a significant period of time. Due to the potential hazard during underground working gas emission generated into the cells and the amount of vented gas is strictly regulated 1. The three characteristics of cell chemistry which indicate charge completion are temperature, voltage and internal cell pressure. As a cell nears full charge, the voltage of the cell, its temperature and pressure all will rise. Full charge detection followed by discharge was achieved under laboratory conditions by monitoring the battery voltage, current and pressure build up terminating the charge when a certain signature occurs (the initially set voltage was reached). Sampling (1 cm3 of headspace gas) was made at regular intervals and the qualitative and quantitative analysis of gases of the battery was made using a QMS (OMNISTAR, Balzers Instruments). Monitoring of gas generation was made during 16 and 72 hours charge periods followed by 12-13 hours discharge periods. The results showed a constant increase in pressure (up to 2 bars) into the checked cells during the charge period, the generated gases being the following: CH4, H2 and O2. The voltage of the three cells increased to 4.40 V while the charge current dropped from 1 A to 0.5 A. During discharge a decrease of the cell voltage was observed a sharp drop being recorded (from 3.0 V to 2.85 V) after 12-13 hours. The excess oxygen generated during the charge period reaching the active sites on the negative plate was recombined from the gaseous state forming hydroxyl ions, so its concentration decreased in the headspace gas. The study showed an increase of up to 19% of H2 into the cells during the 72 hours charge period and up to 15% of H2 into the space between the battery and its outside polycarbonate case, which is not acceptable for underground mining activities. (author)
[en] The principle of the developed new method for pulse charge of batteries with microprocessor control of the electrochemical processes is the use of current pulses with microprocessor control of the period and the amplitude according to the dynamically changing state of the electrochemical system. In order to realize the method described above a programmable current source was developed. It is connected with a Personal Computer via RS232 standard serial interface in order to control the electrochemical processes. The parameters to be set, the graphical presentation of the pulse current and tension, the used quantity of electricity and electrical energy for every pulse and for the process as a hole are shown on the PC display. In order to test dry-charged and wet-charged batteries a specialized current generator was developed. It is connected also with a Personal Computer via R5232 standard serial interface in order to con-trol the testing of the starting capability of the batteries according to the requirements of the Bulgarian State Standard Ell 60095-1. (Author)
[en] Current practice within the nuclear power industry is to use performance discharge tests for condition monitoring to determine when a battery has reached 80% of its rated capacity which is considered the end of its service life. A service test is used every refueling outage to verify that a battery can satisfy its design basis function as defined by the battery duty cycle. A modified performance test is used at intervals of one-fourth the qualified life to satisfy the requirements of both the service and performance tests. The service test done every refueling outage (1.5 to 2 years) verifies the battery will satisfy its safety design function. The duty cycle duration for existing nuclear plants is in the 2 to 8 hour range. Some of the new plant designs have duty cycle durations of 24 to 72 hours. Discharges at the 72 hour rate to end voltage can cause difficulties with charge acceptance at the beginning of recharge for some batteries. The proposed 80% Service Test would use a smaller discharge to yield a percent capacity value for trending and also reduce the risk of recharge issues. This paper presents the proposed test and its possible applications at the existing and future nuclear generating stations and non-nuclear facilities as well. Some preliminary results are also provided
[en] An alternative set-p of a vibrational energy harvester with an array or ceramic piezoelectric transducers is presented in this research. The researcher conducted experimentation on the viability of piezoelectricity as an alternative energy source. From the experimentation conducted, an energy harvester was designed and developed. The prototype primarily consists of piezoelectric transducers and a charger module. The piezoelectric transducer is composed of ceramic type connected in series and parallel combination. Loads, in the form of screws, are positioned on top of each piezoelectric transducer. These screws serve as an inducer to the piezoelectric transducer thereby producing the necessary vibration which in effect creates electromotive field. The module is mounted on top of the electric home generator for testing and simulation. The charger module basically consists of rectifier circuits to convert alternating current to direct current and rechargeable AA/AAA batteries as the temporary energy storage. The energy collected was tested to charge a mobile phone batteries and the likes. To further boost the output current, a darlington configuration using a generator to produce the needed vibration. Through laboratory experiments, the amount of voltage produced is measured in different circuit connection and combination. For simulation purposes, the device, which was made rigid and stable, was mounted on top of the generator to harvest the required vibration. It was tested at different speed of the generator and at various position from the generator top surface. With the existing set-up of the harvester and after performing initial testing, the measured voltaeg is around 2.5V while the current is only about 0.11mA sufficient to charge up 2 AA / AAA batteries. For further boosting the current, two transistors connected in darlington configuration was included which doubled the current output. (author)
[en] Wireless power transfer (WPT) systems have emerged as a key technology for the future charging infrastructure. Besides full system efficiency, the power densities of the transmission coils are key figures of merit. This thesis presents the development and the experimental verification of a fully functional WPT system, consisting of high-temperature superconducting (HTS) coils on the transmitter and the receiver side. Despite a compact coil size, a DC-to-DC efficiency above 97% is achieved.
[en] Highlights: • Temperature rise and charge time constraint charging strategy is introduced. • Genetic algorithm is wielded to optimize the charge current trajectories. • The proposed method can reduce charge time notably with rational temperature rise. • Battery charge performance and aging using the proposed approach are evaluated. - Abstract: Lithium-ion battery fast charging issues have become a main bottleneck of large-scale deployment of electric vehicles. This paper develops a polarization based charging time and temperature rise optimization strategy for lithium-ion batteries. An enhanced thermal behavior model is introduced to improve the solution accuracy at high charging current, in which the relationship between polarization voltage and charge current is addressed. Genetic algorithm (GA) is employed to search for the optimal charging current trajectories. The effects of weighting coefficients of charging time and temperature rise on battery charging performance are discussed. The charging time of the optimized charging protocol is reduced by 50%, and the associated temperature rise is almost identical, compared to 1/3C constant current-constant voltage (CC-CV) charging. Aging experiments demonstrate that the proposed charging method has a similar capacity retention ratio to that of 0.5 CC-CV charging after 700 cycles, thereby accomplishing a good balance between charging speed and lifetime.
[en] The aim of this study is to investigate blood lead levels in workers of lead acid battery factories and the relationship between those levels and the activity of y-glutamyl transferase.(y-GT). Sample of blood were collected during the period from July 2001 to August 2001 from 95 workers of the 2 lead acid battery factories in Amman,Jordan. They were divided into 2 groups of high and low exposure. Results indicated no significant relation between lead blood levels and Y-GT activity (p=0.303) or between blood lead levels and duration of exposure in both groups (p=0.61).However significant relation was found between lead blood level and the type of work. Lead blood level in workers in lead acid battery factories in Jordan are high.In most cases they are higher than the limit permitted by the World Health Organization.Good protection measures should be taken in such factories to avoid the negative impact of high lead blood levels on the health of workers. (author)