Automotive batteries: identify the correct cell type and classification used in common cars Choose the statement that best describes standard “auto” batteries found in passenger vehicles.

Introduction / Context:
Understanding the type of battery used in cars is a fundamental concept in basic electrical engineering and automotive technology. “Primary” batteries are single-use cells, whereas “secondary” batteries are rechargeable. Most automotive starting, lighting, and ignition systems rely on rechargeable batteries, and the construction details (wet cell vs. dry cell) determine maintenance and safety considerations.

Given Data / Assumptions:

• Typical passenger vehicles use lead–acid batteries.
• Lead–acid batteries are rechargeable, hence they are secondary cells.
• Traditional lead–acid automotive batteries contain liquid electrolyte (sulfuric acid solution), which classifies them as wet cells (even maintenance-free designs still contain liquid or absorbed electrolyte).

Concept / Approach:
Classify by two axes: rechargeability (primary vs. secondary) and electrolyte physical state (wet vs. dry). Combine both to determine the correct statement. Automotive batteries provide high cranking current, a hallmark of lead–acid chemistry with liquid electrolyte plates submerged in acid, designed for repeated charge–discharge cycles from the alternator.

Step-by-Step Solution:
1) Identify chemistry: automotive batteries are lead–acid.2) Determine rechargeability: lead–acid auto batteries are rechargeable → secondary.3) Determine electrolyte form: conventional designs use liquid sulfuric acid → wet cell.4) Combine: secondary + wet cell → “secondary wet-cell batteries.”

Verification / Alternative check:
Automotive alternators continuously recharge the battery while the engine is running. This operational behavior confirms that the battery must be secondary (rechargeable). Service manuals and safety labels reference electrolyte handling and venting, consistent with wet-cell architecture (including AGM/VRLA variants, which are still lead–acid wet systems, though often absorbed).

Why Other Options Are Wrong:
Primary wet-cell or dry-cell types are not rechargeable and therefore unsuitable for automotive use. “Secondary dry-cell” usually refers to chemistries like NiMH or Li-ion in sealed formats, not standard car starter batteries.

Common Pitfalls:
Confusing “maintenance-free” with “dry-cell.” Maintenance-free lead–acid batteries still contain electrolyte; they are not dry primary cells.

Final Answer:
Auto batteries are secondary wet-cell batteries.