the lead-acid battery

427 Pages·2014·9.66 MB·English

Battery Performance Characterisation
for Stand-Alone Photovoltaic Systems
CJ de V PURCELL, BSc (Chem), UCT
Energy for Development Research Centre
Energy Research Institute, University of Cape Town
September 1991
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The copyright of this thesis vests in the author. No
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The thesis is to be used for private study or non-
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Published by the University of Cape Town (UCT) in terms
of the non-exclusive license granted to UCT by the author.
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DECLARATION
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examinaattai nuoynn i ve.r sity
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ABSTRACT
One of the main factors limiting optimisation of PV system designs over the life
of the system has been the lack of battery test data appropriate to PV applications.
The main objective of this study was to determine accurate empirical data for
locally available lead-acid batteries which could be used in photovoltaic systems
and to present this data in a format directly applicable to PV system designers.
The study included (i) a review of battery performance regimes typical of PV
systems; (ii) a literature review of lead-acid battery performance and reactions
important to PV applications, battery electrical models, battery life models, a
review of specialist PV battery designs and the interaction of battery and voltage
regulator in PV systems;. (iii) a review of testing and research literature, and the
design of a suite of experimental procedures suitable for characterising batteries
under PV operating regimes; (iv) the design and construction of a specialised
battery test-unit to automatically perform tests and capture data; (v) selection,
testing and characterisation of five generic types of batteries which could be used
in local PV applications.
The five types of lead-acid battery were:
1) conventional calcium alloy positive and negative grids, flat plate, flooded
electrolyte, vented casing;
2) low antimony alloy positive grid, conventional calcium negative grid, flat
plate, flooded electrolyte, vented casing;
3) low antimony alloy positive grid, heat treated calcium negative grid, flat
plate, immobilised absorbed electrolyte, sealed casing with 0 cycle gas
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recombination;
4) antimony alloy positive and negative grids, flat plate, flooded electrolyte,
vented casing;
5) antimony alloy positive and negative grids, tubular plate, flooded
electrolyte, vented casing.
Selenium grid alloy cells and gelled electrolyte batteries were not represented
amongst the batteries tested, owing to problems of availability or cost.
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Performance data presented at the temperatures and low currents typical of PV
applications include discharge and capacity curves, charge curves and charge
efficiency curves. Performance under PV cycling regimes is analysed. Life cycle
estimates and associated battery life cycle costs are tabulated, with discussion of
special considerations when selecting these batteries for a PV application. The
battery data generated has also been incorporated in a database battery model in
a PV system simulation package, PVPRO, for improved battery performance
modelling.
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ACKNOWLEDGEMENTS
I would like to thank the following people and organisations for their
contributions to this research project:
Dr Anton Eberhard and Bill Cowan for their guidance and supervision at
various stages of this dissertation,
the organisations in the battery and photovoltaic industries that so readily
made their equipment available for testing,
colleagues at the Energy for Development Research Centre for their
persistent encouragement and interest,
Susan, especially, for her patience and understanding during this time.
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