An automated storage and retrieval system comprising: a track system comprising a first set of parallel tracks arranged in a horizontal plane and extending in a first direction, and a second set of parallel tracks arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, said first and second sets of tracks (110, 110) forming a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each grid cell comprising a grid opening defined by a pair of adjacent tracks (110a, 110b) of the first set of tracks and a pair of adjacent tracks (111a, 111b) of the second set of tracks; a plurality of storage columns located beneath the track system, wherein each storage column is located vertically below a grid opening and arranged to store a stack of storage containers; a container handling vehicle for lifting at least one storage container stacked in the stacks, the container handling vehicle being configured to move laterally on the track system above the storage columns to access the storage containers via the grid openings, wherein the container handling vehicle comprises a lower part comprising at least one storage compartment for storing a storage container, an upper part arranged vertically above the lower part, a wheel assembly for guiding the container handling vehicle along the track system and a power supply compartment for accommodating a replaceable power supply; a replaceable power supply for accommodation in the power supply compartment, having a power supply charging connection; and a charging station for charging of the replaceable power supply, the charging station comprising a charging connection configured to create an electrical connection with the power supply charging connection and a power supply support for releasably supporting the power supply during charging; the power supply compartment is arranged in the upper part of the container handling vehicle and is configured to receive the replaceable power supply via an opening facing towards the first direction or the second direction; wherein the power supply support comprises two laterally extending guide arms (43a,43b) between which the replaceable power supply may be supported; the replaceable power supply comprises a support rib arranged on each of two opposite sides of the power supply, each support rib arranged to interact with a corresponding guide arm (43a,43b) of the power supply support; and each support rib comprises a recess or protrusion for interaction with a corresponding protrusion or recess, respectively, arranged on the corresponding guide arm (43a,43b), wherein the interacting recess and protrusion are arranged such that the power supply is prevented from lateral movement when supported by the power supply support, wherein the container handling vehicle comprises an auxiliary battery to allow movement of the container handling vehicle when void of the replaceable power supply. a track system comprising a first set of parallel tracks arranged in a horizontal plane and extending in a first direction, and a second set of parallel tracks arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, said first and second sets of tracks (110, 110) forming a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each grid cell comprising a grid opening defined by a pair of adjacent tracks (110a, 110b) of the first set of tracks and a pair of adjacent tracks (111a, 111b) of the second set of tracks; a plurality of storage columns located beneath the track system, wherein each storage column is located vertically below a grid opening and arranged to store a stack of storage containers; a container handling vehicle for lifting at least one storage container stacked in the stacks, the container handling vehicle being configured to move laterally on the track system above the storage columns to access the storage containers via the grid openings, wherein a replaceable power supply for accommodation in the power supply compartment, having a power supply charging connection; and a charging station for charging of the replaceable power supply, the charging station comprising a charging connection configured to create an electrical connection with the power supply charging connection and a power supply support for releasably supporting the power supply during charging; the power supply compartment is arranged in the upper part of the container handling vehicle and is configured to receive the replaceable power supply via an opening facing towards the first direction or the second direction; wherein the power supply support comprises two laterally extending guide arms (43a,43b) between which the replaceable power supply may be supported; the replaceable power supply comprises a support rib arranged on each of two opposite sides of the power supply, each support rib arranged to interact with a corresponding guide arm (43a,43b) of the power supply support; and each support rib comprises a recess or protrusion for interaction with a corresponding protrusion or recess, respectively, arranged on the corresponding guide arm (43a,43b), wherein the interacting recess and protrusion are arranged such that the power supply is prevented from lateral movement when supported by the power supply support, wherein the container handling vehicle comprises an auxiliary battery to allow movement of the container handling vehicle when void of the replaceable power supply.