Automotive Electronics Practice Test

A fully charged 12-volt battery should indicate what voltage?

1. 12.6 volts or higher

2. A specific gravity of 1.265 or higher

3. 12 volts

4. Both a and b

The correct answer is: Both a and b

A fully charged 12-volt battery should indicate a voltage of 12.6 volts or higher. This voltage represents the state of charge of a lead-acid battery at rest, fully charged, and not under load. When a battery reaches this voltage level, it indicates that it has maintained sufficient chemical activity to provide reliable power for starting and operating a vehicle's electrical systems. Additionally, specific gravity is another measurement used to ascertain the state of charge in lead-acid batteries. A specific gravity of 1.265 or higher corresponds to a fully charged battery; it reflects the density of the electrolyte compared to pure water and gives insight into the battery's health and charge status. Thus, both voltage measurement (12.6 volts or higher) and specific gravity (1.265 or higher) are valid indicators confirming that a battery is fully charged, supporting the conclusion that the combined response is the correct choice.