1. Electrical Draw: When the car is turned off, certain electrical components such as interior lights, security systems, and infotainment systems continue to draw power from the battery, though it might be a minimal amount. Leaving the overhead lights on adds to this electrical draw and increases the energy drain on the battery.
2. Gradual Discharge: Over time, this continuous power draw without the engine running to recharge the battery will gradually discharge it. The duration it takes for the battery to be drained completely depends on factors like battery capacity, vehicle electrical systems, and ambient temperature. However, in general, leaving the lights on overnight (approximately 8-10 hours) is often enough to significantly deplete the battery.
3. Risk of Deep Discharge: Deep discharge occurs when the battery's voltage drops below a critical level. Prolonged draining by lights or other accessories, which might not even be noticeable at first, can eventually lead to deep discharge over an extended period like a full night. Deep discharge can cause permanent damage to the battery's cells, reducing its lifespan or even completely ruining it.
4. Reduced Cranking Power: A severely drained battery may not have enough power left to start the car in the morning. When you turn the ignition key, there might be a clicking sound instead of the engine cranking because there's insufficient electrical power to engage the starter motor.
Therefore, it's essential to avoid leaving the car lights or other non-essential accessories on for extended periods when the engine is off, especially throughout the night, to prevent battery drainage and related problems.
