How is a vehicle's electrical system typically powered when the ignition is off?

When the ignition is off, a vehicle’s electrical system is primarily powered by the main battery and any parasitic draws. The main battery supplies power to various components in the vehicle that may still need to operate even when the engine is not running, such as the car's clock, radio, and security system. These components draw a small amount of current from the battery, referred to as parasitic draws, which is typically in the range of milliamps.

This is why the battery is essential for maintaining power to these systems when the vehicle is not in operation. While the alternator is responsible for charging the battery and powering the vehicle’s electrical system when the engine is running, it is inactive when the ignition is off. Rechargeable capacitors and solar panels are not standard features in most vehicles for maintaining power in this context, making the battery the sole source of electrical energy during such conditions.