An Ultrasonic Approach to Measure the Density of Battery Electrolyte

A new ultrasonic method for measuring the density of open-type lead-acid battery electrolyte is presented. This method is based on the theory that the velocity of sound in a liquid depends on the density of the liquid. The method consists of using 2 buffers enclosing the liquid in a symmetrical arrangement with a transducer fixed to each buffer. Using a measuring cell controlled by the Micro Control Unit, the velocity of sound in liquid is measured, to establish a database relating velocity, density, and temperature. The velocity data are processed using the method of polynomial fitting, to obtain the functions between velocity and density at different temperatures and for finite error analysis. This method can achieve a measurement accuracy of 0.001 g/cm³, and the advantages are: 1) real-time, 2) high accuracy, 3) small size, 4) on-line monitoring, and 5) high reliability.