Abstract: A mobile power supply housed within a wheeled trailer which can be towed to various locations, particularly remote locations, for providing electrical power as needed for operating equipment or for charging of batteries or other electrical supply devices at such remote locations. The apparatus includes a unique trailer design including venting means for preventing the accumulation of hydrogen normally associated with high power battery operation, particularly charging thereof and therewith, by monitoring hydrogen at all times within the trailer interior and selectively passively and actively venting the interior environment when hydrogen levels are high or whenever necessary. A unique roof design is included for gathering hydrogen near the upper portion of the interior roof construction adjacent to a venting outlet to facilitate expelling thereof.

Abstract: Enclosure for holding an electrical device with dual access panels for safely limiting access to the device while allowing maintenance thereof. The housing defines an access opening with a limited accessing construction thereover. Interior and exterior panels are included each movable to be closed and opened. The interior panel is preferably transparent to facilitate viewing therethrough. The exterior panel is preferably metal and is hinged to the housing for movement between closed and opened positions. Individual accessing apertures can be defined in the interior and exterior panels to allow localized access by servicing personnel. Specific positioning of the access opening in the interior and/or exterior panels provides access to limited areas of the electrical device within the housing and prevents access to other areas for safety. The interior panel can have indicia imprinted thereon to facilitate servicing.