Dolgin TC200PANBJ3 Two-Position Battery Charger with TDM features two integrated battery plates supporting Panasonic and non-OEM generic batteries. It's capable of charging two batteries simultaneously and charges a typical 3050 mAh battery in about 2.5 hours. As the battery is being charged, a diagnostics LCD displays status in volts, amp hours, and percentage of charge. The percentage of charge is estimated using a proprietary algorithm. A built-in Test/Discharge Module (TDM) alows the user to determine whether a battery is new or old and on par with its label. TDM cycles the battery (fully charges and discharges it) and provides a report on its capacity. An auto-detecting USB port is available for charging phones, tablets, and other USB devices. It works when the charger is plugged into AC power or "on-the-go" off of an attached battery.