Heat is a normal event of the chemical reaction when charging lead acid batteries. A certain amount of bubbling of the electrolyte is expected.
Some factors contribute with heat generation, hence there is an increase in bubbling and usage of water.
This effect often is seen with older batteries or charging right after heavy used. The duration of charging increases as battery cells remain under higher current for longer periods of time. This also causes the battery voltage to rise slower than usual. Contributing with more heat generation that will cause the battery to use more water and therefore more bubbling.
Too much water in the cell can result in pooling around the caps and causing corrosion. Water should only be added to fully charge cells as water levels will appear lower when the cells are discharged.
After charging, add enough water to bring the level to the bottom of the vent, about 19mm(3/4in) below the top of the cell.
It’s very important also to verify that the charger is set to the correct charging profile (algorithm) for the installed batteries. When using an algorithm for batteries with higher capacities; the cells will be exposed to higher currents than expected for extended periods of time and generating more heat.
The Original Equipment Manufacturer (OEM) for your machine or vehicle can provide you with the list of pre-loaded algorithms in your charger.
You can also visit our article containing all free to use algorithms files, algorithms description and instructions on how to upload them to your unit: