It is normal for the battery to heat up when charging with battery water.
The principle of charging is that the charger voltage is higher than the battery voltage before to be able to charge it. The greater the difference in electromotive force between the two, the faster the charging, the larger the charging current, so the maximum voltage (no load) of a general 12V charger is 13.2-14 V. During the charging process, the electrolyte will boil and the charging current will be higher. the battery shell will feel a certain temperature. After the battery is fully charged, the temperature rise will decrease and the intelligent auto charger will automatically stop charging.
Battery chargers generally use imported power modules and are currently the most innovative high-frequency electronic circuit intelligent automatic chargers. Low perte and high efficiency. It is suitable for charging 12V and 24V batteries. The charger also has an anti-reverse connection function. If it is not connected or the polarity is reversed, there will be no voltage output. Only correct connection can work normally. overvoltage, overcurrent, overheating and other protections