A patient support system comprising: a patient transport apparatus including: a base frame arranged for movement about floor surfaces, an intermediate frame to provide support to a patient, a powered adjustment device (PD), an apparatus energy storage unit , an apparatus user interface arranged for user engagement to selectively operate the powered adjustment device with power from the apparatus energy storage unit , an apparatus controller in electrical communication with the powered adjustment device (PD), the apparatus energy storage unit , and the apparatus user interface , and an apparatus interface in communication with the apparatus controller ; and the patient support system comprising: a first powered device (PD) including: a first module to perform a powered function, a first device energy storage unit , a first device user interface arranged for user engagement to selectively operate the first module with power from the first device energy storage unit , a first device interface in communication with a first device controller , the first device interface adapted to cooperate with the apparatus interface to facilitate power transfer from the apparatus energy storage unit to the first device energy storage unit , and the first device controller in electrical communication with the first module , the first device energy storage unit , and the first device user interface , characterized in that the first device controller includes a first power module configured to determine a charging level for the first device energy storage unit based on a current state of the apparatus energy storage unit , and to draw power from the apparatus energy storage unit via the apparatus interface and across the first device interface to charge the first device energy storage unit at the charging level, wherein the current state of the apparatus energy storage unit comprises an output level, a load condition or an energization status of the apparatus energy storage unit . a base frame arranged for movement about floor surfaces, an intermediate frame to provide support to a patient, a powered adjustment device (PD), an apparatus energy storage unit , an apparatus user interface arranged for user engagement to selectively operate the powered adjustment device with power from the apparatus energy storage unit , an apparatus controller in electrical communication with the powered adjustment device (PD), the apparatus energy storage unit , and the apparatus user interface , and an apparatus interface in communication with the apparatus controller ; and a first module to perform a powered function, a first device energy storage unit , a first device user interface arranged for user engagement to selectively operate the first module with power from the first device energy storage unit , a first device interface in communication with a first device controller , the first device interface adapted to cooperate with the apparatus interface to facilitate power transfer from the apparatus energy storage unit to the first device energy storage unit , and the first device controller in electrical communication with the first module , the first device energy storage unit , and the first device user interface , characterized in that the first device controller includes a first power module configured to determine a charging level for the first device energy storage unit based on a current state of the apparatus energy storage unit , and to draw power from the apparatus energy storage unit via the apparatus interface and across the first device interface to charge the first device energy storage unit at the charging level, wherein the current state of the apparatus energy storage unit comprises an output level, a load condition or an energization status of the apparatus energy storage unit . <EOS>