What is the battery volt meter reading when the engine is off?

When assessing the battery volt meter reading with the engine off, a reading between 12.2 and 12.6 volts is indicative of a healthy battery state. This range reflects a fully charged battery's resting voltage and is typical for a lead-acid battery after it has rested for a while without any load.

When the engine is not running, there are no additional electrical loads placed on the battery beyond minimal parasitic draw from electrical systems. Therefore, the resting voltage is crucial in evaluating the battery's condition. Measurements below 12.2 can indicate that the battery is undercharged or potentially failing, while readings above 12.6 suggest that the battery is in good health and adequately charged.

In contrast, readings above 12.6 volts generally occur when the engine is running, as the alternator is supplying voltage to the battery and other electrical systems. Reading results for a healthy, stationary battery should typically fall within the 12.2 to 12.6 range.