A charging system for autonomous transport vehicles including at least one charging contact disposed on each pick floor level of a storage and retrieval system, each of the at least one charging contact being located at a transfer station, at least one power supply configured to supply power to the at least one charging contact, and a controller in communication with the transfer station and being configured to communicate information relating to a transfer of items between the transfer station and a predetermined one of the autonomous transport vehicles and to apply power from the power supply to the at least one charging contact for charging the predetermined autonomous transport vehicle corresponding to the transfer and located at the transfer station, wherein the controller is configured to supply power to the charging contacts simultaneously with the predetermined autonomous transport vehicle exchanging items related to the transfer at the transfer station.