Flooded batteries acid stratification

Electrolyte stratification has been responsible for the failure of many flooded battery banks. In simple terms, this phenomenon can be defined as a build-up of higher strength acid at the bottom of the battery. Stratification occurs because sulfuric acid has a higher density than water and, when formed during the charging process, will sink to the bottom of the battery container. Such behaviour results in a decrease in battery capacity due to uneven utilization of the active material [12]. Moreover, if the resulting concentration gradient is allowed to remain for extended periods, premature failure of the battery can occur. 

Acid stratification in flooded batteries used in cycling application, when there is no overcharging with gassing and no electrolyte circulation [54]. 

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