Definition
A type of rechargeable battery that uses lead plates immersed in a sulfuric acid electrolyte to store and release electrical energy through a reversible chemical reaction. Lead-acid batteries are commonly used in piston aircraft and as backup or starting batteries in some turboprop airplanes.
Plain English
A rechargeable battery built from lead plates sitting in acid. It's the same basic battery technology used in cars, and it's one of the standard battery types found in airplanes.
Context Anchor
Seen in aircraft electrical system descriptions, battery servicing information, and preflight discussions of battery condition.
Derivation
Named directly after its two main ingredients: lead (the metal used in the plates) and acid (the sulfuric acid electrolyte). The name simply tells you what's inside the battery.
Why Pilots Care
Lead-acid batteries provide reliable starting power but are heavy; pilots must ensure they remain properly charged to prevent in-flight electrical issues.
Analogy
It's the same basic battery technology that sits under the hood of most cars -- familiar, reliable, and rechargeable.
Intuition Check
Lead-acid does not mean acid is normally exposed or loose around the airplane. It names the battery chemistry; the acid is contained inside the battery.
Example Sentence 1
The trainer was equipped with a standard lead-acid battery, so the pilot checked the electrolyte level during the preflight inspection.
Example Sentence 2
In the turboprop, the lead-acid battery served as the primary source for engine starting and emergency power.