Caution: do not use any metallic vessel, only use plastic vessel & protective wears. Never take open flame near cells. Never connect the cable loosely with the cells / batteries to avoid sparks & chance of explosion / melting
To continue DC charging at constant current till the following conditions of fully charged cells are observed:
Batteries now charged ready - give a rest period of 12 hours for cooling & settling but not more than 24 hours.
To ensure that every cell in a battery bank is maintained in healthy state to give enhanced life and performance, it is advisable to give equalising charge at least once in a year.
Under constant potential mode during operation passive layers form on the plates. This causes variation of sp. gravity & voltage from cell to cell. To take care, the battery bank is to be put on constant current charging at 6% of rated capacity up to 2.75VPC, followed by an extended charge for 12 to 24 hours on constant current charging at 3% of rated capacity.
This helps the cells rejuvenate with fresh layer of active material. All the cells will show approximately same sp. Gravity and voltage. Since low current is given during 3% rated amps of the Ah capacity, this will not affect the activated portion of the plates, but will remove the patches of sulphate from the plates back to the solution, increasing the sp. Gravity of cells. Therefore, it is important to give equalising charge, once in a year, if not earlier.