The type of charger you are using more accurately determines this, but generally, your battery charger is safe to leave powered up and connected to your battery until the battery has reached a full charge. However, most chargers aren’t designed to leave your battery connected indefinitely. The only chargers recommended for extended or storage applications are the 1.5-, 2-, and 3-amp charger/maintainers specifically designed for long-term, slow-trickle charging/maintenance applications. However, problems with the battery, electrical problems in the vehicle, improper connections, or other unanticipated conditions could cause excessive voltage draws. As such, occasionally monitoring the battery and the charging process is recommended.