The TC-400 four position battery charger accepts up to four IDX SSL-JVC50 7.4V Lithium-Ion batteries. It provides fast, safe simultaneous charging. Fully charged batteries are ready in about 3.5 hours. As a battery is charged, its status is displayed in volts, Ah (as counted by the charger fuel gauge) and percent of charge (estimated, using proprietary algorithm). This charger is equipped with the "TDM" option which adds a charge-discharge-charge cycle.