This invention seeks to satisfy a need for a device which can monitor and indicate the state of the charge of a lead acid battery with increased accuracy and sensitivity. The monitor and indicator according to this invention is of the type which responds constantly and promptly to extremely minute changes in specific gravity of the battery liquid electrolyte during charging and discharging of the battery.
Heretofore, specific gravity monitors and indicators for batteries have been hydrostatic systems which tend to be slow in their response to changes in specific gravity of the electrolyte. Furthermore, fluid movement in these hydrostatic indicating systems tends to be extremely slow because of reliance on slow diffusion for operation.
Another serious drawback in the prior art is the lack of any provision for excluding bubbles constantly generated in the electrolyte during charging from entering and clogging the indicator liquid column, thereby retarding, and, in some cases, completely disabling a movable indicator element in the column, such as a float.
In substantially completely eliminating the above and other known deficiencies of the prior art, the present invention provides a battery condition indicator which can be readily built into a commercial lead acid storage battery to continuously monitor and indicate the state of the charge on the battery in response to changes in specific gravity of the battery electrolyte over an extremely narrow range.
The improved accuracy and sensitivity of the indicating system for batteries is achieved by the utilization of a simple continuous flow arrangement for the liquid electrolyte, which includes an effective barrier to the induction of bubbles contained in the electrolyte into the electrolyte column or passage of the indicator, whereby such bubbles are prevented from clogging the indicator in whole or in part. In essence, the present invention makes use of a hydrodynamic indicator system as distinguished from the much more sluggish hydrostatic systems in the prior art.
In a preferred form, the invention utilizes an indicator vertical column for liquid electrolyte having at least a bottom bubble-excluding entrance. At least one buoyant or sunk float is contained in the electrolyte column between submerged spaced stops which are positioned relative to electro-optical emitterdetectors to enable a digital indicating response to the movement of the float to or from the buoyant and sunk positions following changes in specific gravity of the electrolyte over a very narrow range. The interruption of the optical path between emitter and detector elements of the indicator caused by the rise or fall of the float can produce a digital response through a state-of-the-art binary counting circuit connected with the emitter and detector elements and having a suitable display.
Variations in the construction of the indicator and additional features and advantages thereof over the prior art will become apparent during the course of the following detailed description.