Subhas Chalasani - Academia.edu (original) (raw)

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Papers by Subhas Chalasani

$Research paper thumbnail of (Invited) Mapping Electrode and Electrolyte Heterogeneity with High Energy Synchrotron Diffraction$

ECS Meeting Abstracts, 2021

Lead acid batteries are often portrayed as a mature technology with limited capacity and room for... more Lead acid batteries are often portrayed as a mature technology with limited capacity and room for innovation. In reality, lead batteries have significant room for growth since they only utilize a fraction of their active material and have been engineered for SLI applications that lack a battery management system for controlled charge and discharge. In large part these issues are related to chemical heterogeneity that exists at both the pack level and within the battery electrode microstructure. Unlike a lithium ion battery, lead acid electrodes are typically larger laterally and millimeters thick with significant porosity to allow acid penetration. At the particle level, the growth and dissolution of PbSO4 during discharge from the Pb and PbO2 charge species also leads to significant volume change and swings in local acid concentration within the electrode pores. Recently, we have begun analyzing the spatial variation of charge acceptance in lead acid cells using high energy x-ray d...

Proceedings of Power and Energy Systems in Converging Markets

This paper is based on a joint study conducted by Lucent Technologies and Sprint Florida on monit... more This paper is based on a joint study conducted by Lucent Technologies and Sprint Florida on monitoring the state of health of VRLA batteries. The purpose of the study was to see whether ohmic techniques (impedance, resistance and conductance) can accurately predict the state of charge and state of health of the batteries. This study consisted of field testing as well as accelerated laboratory testing. Comparison of the commercial meters and recommendations on minimizing the measurement errors have also been made.

Sixteenth Annual Battery Conference on Applications and Advances. Proceedings of the Conference (Cat. No.01TH8533)

... Chalasani SC Bose, Doug Wilkins, Steve McCluer and Mike J. Model Lucent Technologies Power Sy... more ... Chalasani SC Bose, Doug Wilkins, Steve McCluer and Mike J. Model Lucent Technologies Power Systems, 3000 Skyline Drive, Mesquite, TX 75149. Email: chalasani@?ucent.com George Ledgerwood Sprint PCS, 11880 College Blvd., Overland Park, KS 66210 ...

Journal of Energy Storage, 2015

Inclusion of an appropriate form of carbon as an additive in the negative active material (NAM) i... more Inclusion of an appropriate form of carbon as an additive in the negative active material (NAM) improves the performance of lead-acid batteries in high rate partial state of charge (HRPSoC) cycling. We have used cyclic voltammetry to evaluate the performance of different carbonscarbon black, acetylene black and graphitein this study and found the technique to be useful in separating the capacitive and the Faradaic contributions to the total charge. It is noted that the presence of carbon at the Pb-interface substantially enhances the electrochemical activity and increases the Faradaic charge, while high surface area carbons add to the capacitive charge. The technique is further used to study combinations of carbons as physical mixtures and bilayers. 2015 Published by Elsevier Ltd.

INTELEC. Twenty-Second International Telecommunications Energy Conference (Cat. No.00CH37131)

It has been shown for the first time that the state of health of a lead acid battery can be estim... more It has been shown for the first time that the state of health of a lead acid battery can be estimated accurately by measuring the coup de fouet voltage appearing in the early minutes of the battery discharge. The results obtained from string as well as mono block testing including 12 V batteries and 2 V cells are presented here.

Various anodic and cathodic processes that occur in a valve regulated lead-acid battery (VRLA) un... more Various anodic and cathodic processes that occur in a valve regulated lead-acid battery (VRLA) under float conditions were separated and measured accurately from in situ measurements of volumetric, voltammetric and gas analysis. All of these processes including oxygen evolution, grid corrosion of the positive, hydrogen evolution and oxygen recombination were monitored as the battery changed from a flooded electrolyte state to a starved condition. Grid corrosion of the positive electrode in the starved electrolyte condition was found to be three times greater than in the flooded state

Journal of Applied Electrochemistry, 1982

The accurate determination of the impedance of oxide films in metal/oxide/electrolyte systems is ... more The accurate determination of the impedance of oxide films in metal/oxide/electrolyte systems is shown to be possible through a modified procedure. The film impedance thus determined is found to be quite different from the measured cell impedance for anodic aluminium oxide formed on pure aluminium. The computed values of tan d and conductivity are found to be in agreement with the values reported earlier for anodic and thermal oxides.

INTELEC - Twentieth International Telecommunications Energy Conference (Cat. No.98CH36263)

ABSTRACT