It is feasible to check a car battery’s charge at several important times. The best time is before starting the engine, especially after the car has been parked for several hours or overnight. At this point, the battery has had time to settle, giving a more accurate indication of its resting voltage. Checking in the morning before driving is therefore a simple and useful routine.
You can also check the battery after a long drive to see whether the alternator is charging it properly. However, remember that a voltage reading immediately after driving may be temporarily higher because of the recent charging activity. For a more reliable resting-voltage measurement, allow the vehicle to sit for a few hours before testing. It is also wise to check the battery before a long journey, after the car has been unused for an extended period, or whenever you notice slow engine cranking, dim lights, or difficulty starting.
