The Experts below are selected from a list of 93 Experts worldwide ranked by ideXlab platform
A J Urba - One of the best experts on this subject based on the ideXlab platform.
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failure mode of valve regulated lead acid batteries under high rate partial state of charge operation
Journal of Power Sources, 2004Co-Authors: L T Lam, N P Haigh, C G Phyland, A J UrbaAbstract:Abstract Within the next decade, there will be major changes in automotive technology with the introduction of several new features which will increase significantly the on-board power requirements. This high power demand is beyond the capability of present 14 V alternators and thus a 42 V power network is to be adopted. The new ‘PowerNet’ requires the lead-acid battery to be capable of providing a large number of shallow discharge–charge cycles at a high rate. High-rate discharge is necessary for engine cranking and power assist, while high-rate charge is associated with regenerative braking. The battery will operate at these high rates in a partial-state-of-charge condition, so-called HRPSoC duty. Under simulated HRPSoC duty, it is found that the valve-regulated lead-acid (VRLA) battery fails prematurely due to the progressive accumulation of lead sulfate mainly on the surfaces of the Negative Plates. This is because the lead sulfate cannot be converted efficiently back to sponge lead during charging either from the engine or from regenerative braking. Eventually, the layer of lead sulfate develops to such extent that the effective surface area of the Plate is reduced markedly and the Plate can no longer deliver the high cranking-current demanded by the automobile. A mechanistic analysis of battery operation during HRPSoC duty shows that high-rate discharge is the key factor responsible for the build-up of the lead sulfate layer. Such discharge causes a compact layer of tiny lead sulfate crystals to form on the surface of the Negative Plate and subsequent charging gives rise to an early evolution of hydrogen. Hydrogen evolution is further exacerbated when a high charging current is used.
Patrick T Moseley - One of the best experts on this subject based on the ideXlab platform.
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consequences of including carbon in the Negative Plates of valve regulated lead acid batteries exposed to high rate partial state of charge operation
Journal of Power Sources, 2009Co-Authors: Patrick T MoseleyAbstract:Abstract In power-assist hybrid electric vehicles (HEVs) batteries are required to operate from a partial-state-of-charge baseline and to provide, and to accept, charge, for short periods, at very high rates. Under this regime conventional lead–acid batteries accumulate lead sulfate on the Negative Plate and fail quickly. This failure mode can be effectively countered by the inclusion of certain forms of carbon at greater concentrations than have been used in lead–acid batteries in the past. So effective is this preventive measure that VRLA batteries benefiting from the inclusion of such carbon have been able to substitute for nickel metal hydride batteries in power-assist HEVs with no significant loss of performance. There has been much speculation about the function of the carbon that is providing this remarkable improvement. This paper aims to review the several mechanisms that have been proposed as possibly playing some contributory role.
B Zachauchristiansen - One of the best experts on this subject based on the ideXlab platform.
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failure mode of the Negative Plate in recombinant lead acid batteries
Journal of Power Sources, 1994Co-Authors: S. Atlung, B ZachauchristiansenAbstract:Abstract Experimental recombinant valve-regulated lead/acid batteries failed after 250 to 350 deep cycles. The failure was attributed to the Negative electrode which showed loss of capacity. When the cells were converted to operation in the flooded mode, they delivered up to 1400 deep cycles. The failure mechanism is assumed to be sulfation due to insufficient recharge. A simple model for the partial currents during recharge is used to analyse the role of recombination and hydrogen and oxygen evolution in the failure mechanism. It is concluded that, at high recombination efficiencies, hydrogen evolution prevents the complete recharge of the Negative Plate, thus limiting the cycle life.
Kathryn R Bullock - One of the best experts on this subject based on the ideXlab platform.
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carbon reactions and effects on valve regulated lead acid vrla battery cycle life in high rate partial state of charge cycling
Journal of Power Sources, 2010Co-Authors: Kathryn R BullockAbstract:VRLA batteries in hybrid electric vehicles are operated at a partial state of charge with high current draws for acceleration and regenerative braking. Adding larger amounts of carbon particles to the Negative Plate material extends battery life. Water loss and increasing internal resistance are a cause of a subsequent failure mode that is related to the carbon and other organic additives in the Negative Plate. Previous studies of the composition and volume of gases vented from valve-regulated lead-acid (VRLA) batteries and acid-limited batteries at various temperatures and current levels are reviewed and used to develop an understanding of carbon reactions and their effects on battery state of health.
L T Lam - One of the best experts on this subject based on the ideXlab platform.
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failure mode of valve regulated lead acid batteries under high rate partial state of charge operation
Journal of Power Sources, 2004Co-Authors: L T Lam, N P Haigh, C G Phyland, A J UrbaAbstract:Abstract Within the next decade, there will be major changes in automotive technology with the introduction of several new features which will increase significantly the on-board power requirements. This high power demand is beyond the capability of present 14 V alternators and thus a 42 V power network is to be adopted. The new ‘PowerNet’ requires the lead-acid battery to be capable of providing a large number of shallow discharge–charge cycles at a high rate. High-rate discharge is necessary for engine cranking and power assist, while high-rate charge is associated with regenerative braking. The battery will operate at these high rates in a partial-state-of-charge condition, so-called HRPSoC duty. Under simulated HRPSoC duty, it is found that the valve-regulated lead-acid (VRLA) battery fails prematurely due to the progressive accumulation of lead sulfate mainly on the surfaces of the Negative Plates. This is because the lead sulfate cannot be converted efficiently back to sponge lead during charging either from the engine or from regenerative braking. Eventually, the layer of lead sulfate develops to such extent that the effective surface area of the Plate is reduced markedly and the Plate can no longer deliver the high cranking-current demanded by the automobile. A mechanistic analysis of battery operation during HRPSoC duty shows that high-rate discharge is the key factor responsible for the build-up of the lead sulfate layer. Such discharge causes a compact layer of tiny lead sulfate crystals to form on the surface of the Negative Plate and subsequent charging gives rise to an early evolution of hydrogen. Hydrogen evolution is further exacerbated when a high charging current is used.
