A battery’s ability to power a vehicle’s essential electrical components if the charging system fails is known as its reserve capacity. It represents the time, measured in minutes, that a fully charged battery can continuously deliver 25 amps at 80 degrees Fahrenheit before the battery voltage drops below 10.5 volts. For example, a battery with a rating of 120 signifies it can supply 25 amps for 120 minutes before the voltage declines to an unusable level.
This metric offers a crucial indication of a battery’s endurance and reliability, particularly in situations where the alternator malfunctions. A higher figure indicates a longer period during which the vehicle can operate on battery power alone, providing a significant safety margin and preventing sudden breakdowns. Historically, this measurement became vital with the increased reliance on electrical systems in automobiles, ensuring basic functionality even with charging system issues.
