Optical charge indicator for lead acid battery - utilising changing refractive index of electrolyte density as measurement

摘要

The refractive index of the electrolyte depends on its density which in turn is dependent upon the state of charge and can thus be used to give indication of that state. By measuring the divergence of a light beam passing through a known depth of electrolyte the state of charge can be assessed. This process is simplified by making the optical system fit in the space normally occupied by the battery vent plug thus the depth to which the beam then dips into the electrolyte can be fixed. The optical unit comprises a head fitting in the vent opening which carries the light source and the light sensitive receiver. The rest of the light conducting body carries the diaphragm for determining the initial beam parameters, the refracing surface and the reflecting surface.