A malfunctioning battery may cause large economic losses or in the case of more sensitive equipment, even the loss of human lives.The main parameters in the assessment of a battery are current, voltage, temperature, www.selleckchem.com/products/Oligomycin-A.html state of charge (SoC) Inhibitors,Modulators,Libraries and state of health (SoH). The state of charge is one of the most significant parameters of a battery. It provides key information that is useful for the improvement Inhibitors,Modulators,Libraries of battery operation, performance, reliability and life span. Knowing the state of charge it is possible to avoid an overcharging that would lead to a decrease in working life or even to a battery malfunction [2,3].The measurement of electrolyte density provides an accuracy value of battery SoC. The lead-acid battery uses lead dioxide (PbO2) as the active material in the positive electrode, and metallic lead (Pb) of a very porous structure, as the active material in the negative electrode.

The electrolyte is formed by sulphuric acid (H2SO4) diluted in water (H2O), with concentrations between 8% and 40%, depending on the state of charge and the type of battery. The electrochemical reactions which occur during the process of charging and discharging are described in Equations (1) to (6):During Inhibitors,Modulators,Libraries the charge:Anode?(+):PbSO4+2H2O��PbO2+H2SO4+2H++2e?(1)Cathode?(?):PbSO4+2e?��SO42?+Pb(2)Global?reaction:2?PbSO4+2H2O��Pb+PbO2+2H2SO4(3)During the discharge:Anode?(+):Pb+SO42?��PbSO4+2e?(4)Cathode?(?):PbO2+H2SO4+2H++2e?��PbSO4+2H2O(5)Global?reaction:Pb+PbO2+2H2SO4��2??PbSO4+2H2O(6)According to Equations (4) to (6), during the discharging process both electrodes transform the active material into lead sulphate (PbSO4), with the consequent consumption of H2SO4 and Inhibitors,Modulators,Libraries the release of water to the electrolyte.

As a result the electrolyte density decreases. In the charging process, Equations (1) to (3), the opposite reaction occurs since H2SO4 is released and water is consumed, thereby causing an increase in the electrolyte density.Since the refractive index depends on electrolyte density [1], the former can be used to assess the latter. In addition, Anacetrapib the evolution density versus time curve is a good indicator of battery SoH.Density sensors are based on different principles and may be classified as hydrostatic, electrochemical or electrical, optical [4�C7] and, a final group that includes sensor based on various properties such as ion exchange membrane [8] or electrolyte conductivity [9].

These methods have been studied by several researchers and they all allow measurement of density, but not all of them are suitable for our application. Within the category of selleck catalog optical sensors, the optical fiber sensors have proved to be suitable for many applications and since the 1970s multiple configurations have been developed for applications in physical, chemical, environmental, mechanical measurements, etc., [10].