Wheelift transporters can have a choose from a variety of power options. An electric generator driven transporter can have either an LP gas or diesel engine power source. It can also be powered from an umbilical to 480 V, AC power outlets.  OR, a combination of both.  Wherein shore power is the back-up system.  Very possibly, the transporter can operator from generated power most of the time, but when entering a clean room environment, be switched to a shore power connection.

Lead acid atteries can be an option.  They are the norm currently in industry, particularly in AGV applications, but normally usedfor much lighter loads.  With higher power draws, and long duty cycles, more and larger batteries are required.  For continuous use applications, the swap out to freshly charged batteries will be more complex.  If requiring plug-in charging, the evaluation of battery sizing verses operating time will be a major factor.  Whereas, with a generator source, run time is virtually unlimited.  And, horsepower wise, engines can be sized as required, depending on loads and ramp angle requirements.