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Characterisation of charge voltage of lead‐acid batteries: application to the charge control strategy in photovoltaic systems
Author(s) -
Vela N.,
Aguilera J.
Publication year - 2006
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.698
Subject(s) - overcharge , voltage , lead–acid battery , battery (electricity) , photovoltaic system , charge control , electrical engineering , state of charge , trickle charging , charge (physics) , automotive battery , automotive engineering , computer science , materials science , engineering , power (physics) , physics , thermodynamics , quantum mechanics
In stand‐alone photovoltaic (PV) systems, charge controllers prevent excessive battery overcharge by interrupting or limiting the current flow from the PV array to the battery when the battery becomes fully charged. Charge regulation is most often accomplished by limiting the battery voltage to a predetermined value or cut‐off voltage, higher than the gassing voltage. These regulation voltages are dependent on the temperature and battery charge current. An adequate selection of overcharge cut‐off voltage for each battery type and operating conditions would maintain the highest battery state of charge without causing significant overcharge thus improving battery performance and reliability. To perform this work, a sample of nine different lead‐acid batteries, typically used in stand‐alone PV systems including vented and sealed batteries with 2 V cells and monoblock configurations have been selected. This paper presents simple mathematical expressions fitting two charge characteristic voltages: the gassing voltage (V g ) and the end‐of charge voltage (V fc ) as function of charge current and temperature for the tested batteries. With these expressions, we have calculated V g and V fc at different current rates. An analysis of the different values obtained is presented here focusing in the implication in control strategies of batteries in stand‐alone PV systems. Copyright © 2006 John Wiley & Sons, Ltd.