Hi. That happens because the battery lets out acid through the same terminal. It does not seal well and makes sulfate. Corroborates the battery charge. It usually happens when the charging voltage is higher than adequate (approx. 14 volts), it makes the acid boil and seeks to leave somewhere by pressure. It must also be taken into account that the battery may be defective (its terminals are lead and are usually drilled). Ideally, if all is well, you should change it for a new one. You can prevent your wires from being ruined by placing WD-40 type oil or even Lithium grease on them after thoroughly cleaning the parts with boiling water and if necessary, a scrape on both terminals. This prevents corrosion. Now if your cables and terminals have been exposed to the acid for a long time, it is convenient that you change them as they lose conductive power and end up damaging other parts. A hug.