A lead-acid battery is a rechargeable power source that stores energy using lead plates and an acid electrolyte, valued for its strength, low cost, and dependable performance.
A lead-acid battery is one of the earliest forms of rechargeable battery technology. It was invented in 1859 by the French physicist Gaston Planté and remains in use today due to its dependable performance.
Although a lead-acid battery has a low energy-to-volume ratio and a low energy-to-weight ratio, it can deliver high surge currents. This capability indicates that the battery has a relatively high power-to-weight ratio, making it suitable for applications that require strong bursts of power.
📜 Timeline of Lead Acid Battery History
1859 – Invention by Gaston Planté
o Planté created the first rechargeable cell using two lead sheets rolled into a spiral and immersed in sulfuric acid.
o This was revolutionary because all earlier batteries were primary cells (single use).
1860s – Early Experiments
o Planté demonstrated that repeated charging/discharging improved the battery’s capacity.
o His design was simple but had limited energy storage.
1881 – Improvement by Camille Alphonse Faure
o Faure introduced a paste of lead oxide applied to plates, which increased surface area and capacity.
o This innovation allowed commercial production of lead acid batteries.
Late 19th Century – Industrial Adoption
o Lead acid batteries became widely used in telegraphy, railway lighting, and backup power.
20th Century – Automotive Revolution
o With the rise of automobiles, lead acid batteries became the standard for starter motors due to their ability to deliver high surge currents.
o They also powered early electric vehicles before being replaced by more advanced chemistries.
Modern Era (21st Century)
o Still widely used in cars, UPS systems, forklifts, and renewable energy storage.
o Despite lower energy density compared to lithium ion, they remain popular for their low cost, reliability, and recyclability.
Key Parts of a Lead-Acid Battery Explained
A lead-acid battery is made up of several essential components, each playing a crucial role in its operation and durability.
• Electrolyte: A diluted mixture of sulfuric acid and water that enables electrochemical reactions inside the battery.
• Positive Plate: Constructed from lead dioxide (PbO₂), this plate functions as the cathode during battery operation.
• Negative Plate: Made of sponge lead (Pb), it acts as the anode and supports the flow of electrons.
• Separators: Porous synthetic materials placed between the plates to prevent direct contact while still allowing ionic movement.
• Grid: Wrought lead-calcium alloy grids provide mechanical strength and help conduct electrical current efficiently.
• High-Density Paste: The active material coated on the plates to improve chemical reaction efficiency.
• Case: A durable polypropylene container that houses internal components and safely holds the electrolyte.
• Vents / Flame Arrestor: Designed to release internal gases while blocking external sparks or flames from igniting hydrogen gas.
• Terminals: External connection points that link the battery to the electrical circuit.
Lead-Acid Batteries as Secondary Batteries
Lead-acid batteries are classified as secondary batteries because the chemical reactions inside them are reversible. The chemical substances that produce electrical energy during operation can be restored by supplying an external current, a process known as recharging.
The chemical reaction that releases electrical energy from a secondary battery is referred to as discharging. In contrast, the process of restoring the active materials by passing current back into the battery is called charging.
Lead-Acid Battery Charging Explained
Charging a lead-acid battery is typically carried out by supplying an external current source. When the charger is connected to the battery, the chemical reactions proceed in the reverse direction, restoring the battery’s active materials.
However, if the sulphuric acid or other internal components have already decomposed significantly, the charging process may not be effective. For this reason, regular inspection and periodic checks of the battery are strongly recommended.
During the discharge process of a lead-acid battery, the sulphuric acid inside the battery gradually decomposes and may need replenishment. In some cases, the internal plates can also undergo structural changes over time. As a result, the battery’s efficiency decreases, making charging or replacement necessary.
When car batteries remain in a discharged state for long periods, lead sulfate buildup can occur. This buildup may become very difficult to remove, which is why lead-acid batteries should be recharged as soon as possible to prevent excessive lead sulfate formation.
Chemical Reaction During Lead-Acid Battery Recharging
When a lead-acid battery undergoes recharging, specific chemical reactions occur at both the negative and positive plates. These reactions reverse the discharge process and restore the battery’s active materials.
Negative Plate (Reduction Reaction)
2e⁻ + PbSO₄(s) + H₃O⁺(aq) → Pb(s) + HSO₄⁻ + H₂O(l)
Positive Plate (Oxidation Reaction)
PbSO₄(s) + 5H₂O(l) → PbO₂(s) + HSO₄⁻(aq) + 3H₃O⁺(aq) + 2e⁻
During recharging, the automobile battery operates as an electrolytic cell. The energy required to drive these reverse chemical reactions is supplied by an external power source, such as a car engine.
It is important to note that overcharging a lead-acid battery can lead to the formation of hydrogen gas and oxygen gas. These gases escape from the battery, causing a loss of reactants, which can reduce overall battery efficiency.
Chemical Reaction During Lead-Acid Battery Discharging
When a lead-acid battery is in use, it operates as a galvanic cell and produces electrical energy through chemical reactions. During the discharging process, lead sulfate forms on both electrodes, and a total of two electrons are transferred in the overall reaction.
To ensure safety, the lead-acid battery is enclosed in a thick rubber or plastic casing, which prevents leakage of the highly corrosive sulphuric acid.
Negative Plate (Oxidation Reaction)
Pb(s) + HSO₄⁻ + H₂O(l) → 2e⁻ + PbSO₄(s) + H₃O⁺(aq)
Positive Plate (Reduction Reaction)
PbO₂(s) + HSO₄⁻(aq) + 3H₃O⁺(aq) + 2e⁻ → PbSO₄(s) + 5H₂O(l)
These reactions continue until the active materials are converted into lead sulfate, at which point the battery becomes discharged.
Advantages of a Lead-Acid Battery
Lead-acid batteries remain widely used due to several practical benefits:
• Low Cost: They are more affordable than most other rechargeable battery technologies.
• Reliable Performance: This well-established technology has delivered consistent results for decades.
• High Surge Current: Ideal for applications that demand strong starting power, such as automotive systems.
• Highly Recyclable: Lead and other battery components can be recycled efficiently, helping reduce environmental impact.
• Easy Maintenance: Flooded lead-acid batteries allow simple maintenance by checking and refilling the electrolyte when needed.
Disadvantages of a Lead-Acid Battery
Despite their widespread use, lead-acid batteries face several practical challenges:
• Heavy and Bulky Design: Their lower energy density makes them larger and heavier than modern battery alternatives.
• Limited Lifespan: Capacity gradually decreases over time due to sulfation, especially with poor maintenance.
• Slow Charging Speed: Recharging takes longer compared to lithium-ion batteries.
• Maintenance Requirement: Flooded variants need regular electrolyte level inspections.
• Environmental Risks: Lead and sulfuric acid can be hazardous if recycling is not handled properly.
• Low Energy Efficiency: Charge and discharge efficiency is relatively low compared to newer technologies.
The lead-acid battery continues to play a vital role in modern energy systems due to its rugged construction, proven chemistry, and economical production. Its ability to deliver consistent power under demanding conditions has secured its place in automobiles, backup power units, and renewable energy setups. Even as advanced battery technologies emerge, the lead-acid battery remains a practical and dependable solution where reliability and cost efficiency are essential.
FAQs
1. What is a lead acid battery and why is it important?
A lead acid battery is the world’s first rechargeable battery, invented in 1859. It remains important today because of its low cost, reliability, and ability to deliver high surge currents for vehicles and backup systems.
2. Who invented the lead acid battery?
French physicist Gaston Planté invented the lead acid battery in 1859, and Camille Alphonse Faure improved it in 1881 with a paste design that made mass production possible.
3. How does a lead acid battery work?
It works through chemical reactions between lead dioxide (positive plate), sponge lead (negative plate), and sulfuric acid. During discharge, both plates form lead sulfate while producing electricity; charging reverses the process.
4. What are the main types of lead acid batteries?
o Flooded (wet cell) – requires regular maintenance.
o Sealed (VRLA) – includes AGM and Gel batteries, maintenance free and spill proof.
5. Where are lead acid batteries commonly used?
They power cars, motorcycles, UPS systems, forklifts, renewable energy storage, and even submarines due to their reliability and affordability.
6. How long does a lead acid battery last?
Typically 3–5 years, depending on usage, maintenance, and operating temperature. Proper charging and avoiding deep discharges extend lifespan.
7. What is the future of lead acid batteries?
While lithium ion dominates new markets, lead acid batteries remain relevant for cost sensitive applications, backup power, and industries where durability and recyclability matter most.
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