What does a high reading on the ammeter in flight typically indicate?

A high reading on the ammeter in flight typically indicates that the battery is overcharged. When the alternator is functioning properly and providing more electrical power than the system requires, this excess power can lead to an overcharge condition in the battery. An ammeter measures the flow of current, and a high positive reading suggests that there is a significant flow of current being directed into the battery, indicating it is receiving more charge than it can safely handle.

Operating with an overcharged battery can lead to potential risks, such as overheating and damage to the battery, or even fluid loss in lead-acid batteries due to excessive gassing. Therefore, when pilots observe a high reading on the ammeter, it serves as a critical warning sign to take corrective action to avoid compromising the integrity of the electrical system and battery health.