Patent ID: 8689943

Claim:
A lift truck comprising: a tractor unit; a primary energy storage device disposed on the tractor unit, the primary energy storage device adapted to provide operating power to the tractor unit; a vertically movable platform mounted relative to the tractor unit, the platform being vertically movable between an upper position and a lower position; a rechargeable secondary energy storage device disposed on the platform, the rechargeable secondary energy storage device being rechargeable upon moving the platform toward the lower position; an energy transfer control circuit adapted to sense a voltage potential difference between the primary energy storage device and the rechargeable secondary energy storage device; a primary side sensor circuit and a secondary side target, such that when the primary side sensor circuit and secondary side target are aligned, a transfer coupling sense circuit indicates an aligned condition to the energy transfer control circuit; and the rechargeable secondary energy storage device including at least one capacitor, the at least one capacitor adapted to accept an energy transfer from the primary energy storage device and temporarily store the energy transfer, the rechargeable secondary energy storage device further including a DC-to-DC voltage converter, the voltage converter adapted to convert a voltage from the at least one capacitor to a recharge voltage to recharge the rechargeable secondary energy storage device, wherein the at least one capacitor is electrically connected between the primary energy storage device and the DC-to-DC voltage converter when the primary side sensor circuit and the secondary side target are aligned such that the DC-to-DC voltage converter does not directly connect to the primary energy storage device.