Batteries: dry cell, lead storage cell, fuel cells
Electrochemistry · Chemistry
Study notes
Why does a car battery need 6 cells? What happens on discharge? Step 1: Each Pb/PbO₂ cell gives ~2.0 V; 6 × 2 = 12 V. Step 2: Discharge: Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O. Step 3: Acid consumed → density drops — a hydrometer reads charge state. Step 4: Recharge reverses it (electrolytic mode); over-discharge sulphates plates permanently. Lead-acid: heavy, cheap, recyclable — still king for starter motors.