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It is noticed that durmg charging
there is a rise in voltage
energy is absorbed by the cell
specific gravity of H2тАЛSO4тАЛ is increased
all of the above
there is a rise in voltage
During the charging process of a lead-acid battery, external electrical energy is converted into chemical energy, leading to a rise in terminal voltage, consumption of water, and an increase in the concentration of the electrolyte.
During the charging process of a lead-acid battery, external electrical energy is converted into chemical energy, leading to a rise in terminal voltage, consumption of water, and an increase in the concentration of the electrolyte.
2PbSO4тАЛ+2H2тАЛO+ElectricalEnergyтЖТPb+PbO2тАЛ+2H2тАЛSO4тАЛ
As charging occurs, current flows in the reverse direction of discharge. The chemical reaction at the positive plate is PbSO4тАЛ+2H2тАЛOтЖТPbO2тАЛ+H2тАЛSO4тАЛ+2H++2eтИТ, while at the negative plate it is PbSO4тАЛ+2eтИТтЖТPb+SO4тАЛ┬░2тИТ. These reactions consume lead sulfate and regenerate lead peroxide (PbO2тАЛ) at the anode and spongy lead (Pb) at the cathode, thereby increasing the specific gravity of the sulfuric acid (H2тАЛSO4тАЛ).
Charging is an endothermic process in its initial stage.
Specific gravity of electrolyte rises as H2тАЛSO4тАЛ is produced.
Terminal voltage becomes higher than the nominal EMF of the cell during charging.
Gassing (hydrogen/oxygen evolution) occurs towards the end of the charge cycle.
Reversibility of chemical reaction
High energy density
Sulfation if kept in discharged state
Acid spills can cause corrosion
Automotive starting systems
Uninterruptible Power Supplies (UPS)
Solar power storage
When a battery is fully charged, gassing occurs which can lead to water loss.
Option A is correct as charging EMF exceeds discharge EMF.
Option B is correct because the cell absorbs electrical power.
Option C is correct as SO4тАЛ ions are released from plates back into the electrolyte.
D is correct тАФ all the listed effects (voltage rise, energy absorption, and specific gravity increase) are fundamental indicators of the lead-acid battery charging process.
Always remember that in lead-acid cells, specific gravity is a direct proxy for the state of charge (SoC). A higher specific gravity indicates a higher charge level.