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Why are lead-acid batteries widely used for starting car engines?
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Cutaway view of an alkaline–manganese dioxide power cell.
Lead-acid batteries are the standard choice for starting internal-combustion engines primarily due to their reliability, performance, and cost-effectiveness. Their widespread use in automotive starting-lighting-ignition (SLI) applications is driven by several key factors:12
- High Current Capability: They provide the high current demand necessary to start engines across a wide range of ambient temperatures.2
- Reliability and Cycle Life: They offer high reliability over hundreds of shallow-depth discharge cycles.2
- Cost-Efficiency: Lead is significantly less expensive per kilogram or per ampere-hour than other materials like nickel, cadmium, lithium, or silver.2
- Technical Advantages: They feature a high cell voltage of 2.1 volts, ease of fabrication through processes like casting, and a high degree of salvageability.2
- Shelf Life: They maintain a comparatively good shelf life for a rechargeable system when stored.2
While their energy density is relatively low compared to other systems, their ability to deliver high power for short durations makes them uniquely suited for the requirements of starting a vehicle.12