When the input voltage (AC adapter or car charger) is stopped suddenly, the charger will be in a low current status automatically and descend battery’s discharging current to 4uA to avoid internal damage to prolong the battery life span.
 When charging finished its full charge, it will monitor the battery continuously. It restarts charging if the battery’s voltage drops below 4.0V. So it keeps the battery fully charged without having constantly applying current. This feature is designed to prolong the life of the battery while also giving you a fully charged battery when it is required. However, it is advised that once the charge has finished its safer, and better for your battery to remove it from the battery charger.