That’s why you may have seen people add water to a battery when the liquid inside seemed low.
As the battery discharges, the positive and negative plates gradually turn into lead sulfate.
It’s either present in the water solution as an electrolyte, or absorbed into the lead plates.
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In batteries that aren’t sealed, it is necessary to add water from time to time.
When that happens, it has to be replaced.
The sulfuric acid, on the other hand, doesnt go anywhere.
In fact, evaporation is actually one way to obtain sulfuric acid from battery electrolyte.
While using tap water is fine in some situations, most battery manufacturers recommend distilled or deionized water instead.
