Question 68 OSE02 - Assistant Engineer - OSV

The Correct Answer is D **Explanation for Option D (Correct):** Option D states: "The battery electrolyte should be allowed to thaw, and then the battery should be recharged as necessary before attempting to start the engine." When battery electrolyte freezes, it indicates that the battery is severely discharged (a fully charged lead-acid battery’s electrolyte freezing point is well below -60°F/-51°C, while a discharged battery's freezing point can be as high as 20°F/-6°C). Attempting to use or charge a frozen battery can cause permanent physical damage to the plates and case due as the ice expands. Therefore, the priority is to allow the battery to thaw naturally and safely in a warm environment. Once thawed, the battery must be recharged because its discharged state was the cause of the freezing and it cannot perform the cranking function until restored to a healthy state. **Why the other options are incorrect:** * **A) The battery electrolyte should be allowed to thaw, and then the battery electrolyte should be diluted with distilled water as necessary before attempting to start the engine.** This is incorrect. Once the battery has thawed, distilled water should only be added if the fluid level is low, but the concentration (specific gravity) of the electrolyte should never be intentionally diluted. Diluting the acid concentration reduces the battery's performance and is not a standard procedure following freezing. * **B) The engine should be started by means of jumper cables connected to another battery without any particular concern regarding the electrolyte being frozen.** This is incorrect and potentially dangerous. Connecting jumper cables and demanding high current from a frozen battery can cause internal damage (warping or cracking of the plates/casing) due to the extreme stress and expansion/contraction of the ice, which could lead to acid leakage or even explosion. The frozen battery must be thawed before any further action is taken. * **C) The battery electrolyte should be thawed by means of a battery charger, and then the battery should be recharged as necessary before attempting to start the engine.** This is incorrect. Using a battery charger to actively thaw the electrolyte by applying current is extremely dangerous. The resistance in the frozen battery will generate excessive heat rapidly, potentially cracking the casing, boiling the fluid violently, or causing an explosion due to internal pressure build-up and hydrogen gas evolution while the vents may be blocked by ice. Thawing must be done passively in a warm environment.