An elevator system, comprising: an elevator car (22, 22') that is configured for movement along a path; an elevator car power supply (30, 30') supported for movement with the elevator car (22, 22'), the power supply (30, 30') including a plurality of power sources; and an exchange station near the path and configured to remove, from the elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below a selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; characterised in that the elevator system further comprising: a second elevator car; and a second elevator car power supply (30, 30') supported for movement with the second elevator car, the second elevator car power supply (30, 30') including a plurality of power sources, wherein the exchange station is configured to remove, from the second elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below the selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; wherein the elevator system comprises a plurality of vertical paths (74, 76, 78) and at least one horizontal transition path extending between the vertical paths (74, 76, 78), wherein the elevator car power supply is supported on the elevator car, the second elevator car power supply is supported on the second elevator car, the elevator car and the second elevator car are each configured to move along the horizontal transition path, and the exchange station is in a location to remove and replace the selected number of power sources while the elevator car or the second elevator car is at a corresponding location along the horizontal transition path. an elevator car (22, 22') that is configured for movement along a path; an elevator car power supply (30, 30') supported for movement with the elevator car (22, 22'), the power supply (30, 30') including a plurality of power sources; and an exchange station near the path and configured to remove, from the elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below a selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; characterised in that the elevator system further comprising: a second elevator car; and a second elevator car power supply (30, 30') supported for movement with the second elevator car, the second elevator car power supply (30, 30') including a plurality of power sources, wherein the exchange station is configured to remove, from the second elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below the selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; remove, from the elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below a selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; characterised in that the elevator system further comprising: a second elevator car; and a second elevator car power supply (30, 30') supported for movement with the second elevator car, the second elevator car power supply (30, 30') including a plurality of power sources, wherein the exchange station is configured to remove, from the second elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below the selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; a second elevator car; and a second elevator car power supply (30, 30') supported for movement with the second elevator car, the second elevator car power supply (30, 30') including a plurality of power sources, wherein the exchange station is configured to remove, from the second elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below the selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; remove, from the second elevator car power supply (30, 30'), a selected number of the power sources that have a capacity below the selected level and replace each of the removed number of the power sources with a replacement power source having a capacity above the selected level; wherein the elevator system comprises a plurality of vertical paths (74, 76, 78) and at least one horizontal transition path extending between the vertical paths (74, 76, 78), wherein the elevator car power supply is supported on the elevator car, the second elevator car power supply is supported on the second elevator car, the elevator car and the second elevator car are each configured to move along the horizontal transition path, and the exchange station is in a location to remove and replace the selected number of power sources while the elevator car or the second elevator car is at a corresponding location along the horizontal transition path.