What causes a sudden complete power loss in a 2012 Focus?

[MaverickLynn]

Here are the reasons for a sudden complete power loss in a 2012 Focus: 1. Sudden power loss after parking for a period: Under normal circumstances, the battery won't lose power even if left unused for days or weeks unless there's an internal battery issue or parasitic drain from vehicle electrical equipment. Another possible reason is leaving lights on while the vehicle is parked, causing the battery to drain over time. In such cases, check for any aftermarket installations like navigation systems or dash cams. Also, ensure doors and trunk are properly closed, as unclosed compartments will keep interior lights illuminated. Develop good vehicle usage habits: always turn off all electrical components (AC, audio system, reading lights, headlights, etc.) when the engine is off. 2. Sudden complete power loss during normal operation: Possible causes include alternator failure (not generating electricity) leading to battery depletion, or damage to power supply system wiring/control modules causing complete power loss. In these situations, towing to a repair shop for inspection and maintenance is necessary.