When the Xtreme is ON, the row of 5 diodes at the bottom of the front will light up in turn, with the top flashing LED showing how far charging has progressed. When full charge has been reached, all diodes light constantly. In some cases, the fifth diode keeps on blinking, but does not light up constantly, no matter how long charging continues. Sometimes it will show constant light after charging has been stopped. This is normal, caused by tolerances in the circuits, and is no cause for alarm. The battery is charged to the same level. If the Xtreme is OFF, no diodes will light when full charge has been reached.