In this topic, you study the definition and terms used for Battery Charging.
When a battery is receiving electrical energy from external d.c. source it is said to be the charging.
Following terms used for Battery Charging
Charging p.d. The potential difference at which the cell is charged is known as charging p.d. The charging p.d. is 2.5 volt to 2.75 volts per cell, for example for charging a 6 volt battery the potential difference should be 7.5 volts.
Fully charged p.d. The potential difference Of the cell at full charged condition is known as fully charged p.d. It varies from 2.2 V to 2.5 V per cell.
Discharging. When a cell is delivering power or current to the elec-trical load it is said to be discharging.
Fully discharged p.d. The potential difference at fully discharged condition is called fully discharged potential difference. It is I .7 V per cell.
Specific gravity. The ratio of the weight of any liquid and water of equal volume is called the specific gravity of that liquid. The specific gravity of the electrolyte in full charging condition is 1250 to 1280 and on discharging condition 1150-1200.
Charging rate. The rate in amperes at which the cell is charged is called the charging rate. The charging rate depends upon the method of charging and makers instructions. The normal charging rate is 4 to 6 A but new battery is charged at low rate that is known as initial charging.
Topping up. To maintain the level of electrolyte up to 10 mm to 20 mm above the plates is called topping up. For recharging a battery the distilled water is added to maintain the level of electrolyte.
Gassing. When a cell is put on charge and it reaches to full charged condition gasses comes out of the cell. It is known as gassing. The electrical energy now is not being converted into chemical shape but it decomposes the electrolyte so the gasses are released.