Exam Question

### (a) Hazards Associated with Batteries (4 Marks)
The primary hazards associated with the large battery banks found on board ships are:
1. **Generation of Explosive Gas:** During the charging process, particularly the final stages, electrolysis of the water in the electrolyte produces hydrogen gas. Hydrogen is highly flammable and can form an explosive mixture with air (explosive limits are approximately 4% to 74% by volume). A small spark or static discharge can ignite this mixture, causing a severe explosion.
2. **Electric Shock and Short Circuits:** Ship battery banks, especially those for emergency power or engine starting, operate at high voltages (e.g., 24V, 110V, or higher) and have a very high current-delivering capacity. Accidental contact with live terminals can cause fatal electric shock. Furthermore, dropping a metallic tool across the terminals can create a short circuit, resulting in a high-current arc flash, molten metal spray, and intense heat, posing severe burn and fire risks.