🔍 Key Concepts

• Nickel-cadmium (Ni-Cad) vs. lead-acid battery characteristics (voltage per cell, maintenance, size, and cost) • Standby service definition – batteries that sit charged and are used only when normal power fails • How different battery types hold charge over time and what kind of maintenance they typically need

💭 Think About

• Ask yourself: In standby service, what is the MOST important performance factor – initial cost, physical size, charge retention, or maintenance? • Compare the typical voltage per cell for lead-acid vs. nickel-cadmium batteries. Does that really reduce the number of cells and space needed as much as the choice suggests? • Think about whether any battery type used on vessels is truly “no maintenance,” or if that claim should make you suspicious.

✅ Before You Answer

• Verify which battery type is known for better long‑term charge retention when not in regular use. • Check if higher output voltage per cell is actually a true statement for nickel‑cadmium compared with lead‑acid. • Consider whether lower purchase cost is realistic for nickel‑cadmium batteries compared to lead‑acid.