vhbw Travel Charger Power Supply for iRobot Roomba 400, 405, 410, 415, 4, 531, 532, 535, 540, 660, 670, 780, 4000, 4100, 4188, 4260.0914, 80501, 8070 (Electronics)
Contrary to other reviews I can confirm that the power supply for the Roomba 780 matches. The battery is charged, the Roomba does not report errors. Therefore, the AC adapter / charger seems to fulfill its purpose and to replace the original charger