Dolgin TC400PANBL3 Four-Position Battery Charger with TDM features four integrated battery plates supporting Panasonic and non-OEM batteries. It's capable of charging four batteries simultaneously and charges a typical 3,050 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) allow 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.