The conversion of chemical energy to electrical energy enables a battery to operate and use the stored energy or electricity. When the positive and negative plates of a battery are immersed in electrolyte (sulfuric acid and water), a chemical reaction is created and the sulfur ions move in and out of the solution. This produces a battery’s energy or charge. During discharge, some sulfuric acid turns into water and some lead oxide to lead sulfate. When charged, the water is converted back to sulfuric acid and the lead sulfate is converted back to spongy lead.
The chemical reaction shown below is reversible, as indicated by the double stacked arrows. During a discharge, the reaction proceeds from left to right; during a charge, the reaction proceeds from right to left.
A battery’s capacity is the amount of energy (measured in amp-hours) that the battery can provide to the load (equipment) under a specific set of conditions (discharge rate, temperature, age, etc.).
Also, batteries have different “starting” and “fully charged” specific gravity measurements based on battery design, function, application, and the operational environment. Understanding and monitoring specific gravity readings of deep-cycle batteries is critical to ensuring reliable charge performance and achieving optimum battery life.