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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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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 H2SO4 is increased
all of the above
all of the above
Quick Summary: 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.
2PbSO4+2H2O+ElectricalEnergy→Pb+PbO2+2H2SO4
As charging occurs, current flows in the reverse direction of discharge. The chemical reaction at the positive plate is PbSO4+2H2O→PbO2+H2SO4+2H++2e−, while at the negative plate it is PbSO4+2e−→Pb+SO4°2−. These reactions consume lead sulfate and regenerate lead peroxide (PbO2) at the anode and spongy lead (Pb) at the cathode, thereby increasing the specific gravity of the sulfuric acid (H2SO4).
Charging is an endothermic process in its initial stage.
Specific gravity of electrolyte rises as H2SO4 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 SO4 ions are released from plates back into the electrolyte.
D is correct — 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.