Abstract: A power adaptor includes an elongated and portable body having a pair of axially opposed end portions. The body includes a pair of diametrically offset L-shaped arms protruding outwardly therefrom. Another of the body end portions and the L-shaped arms define a plurality of respective electrical contacts for receiving a corresponding male receptacle associated with an auxiliary power device. The body further includes a flap directly conjoined to another body end portion and repeatedly pivotal between open and closed positions for sheltering the electrical contact associated with another body end portion during non-operating conditions. The power adaptor further includes a mechanism for regulating power distribution to the electrical contacts such that the power distribution can be automatically disconnected from the body when the tractor trailer power supply source drops below a minimum threshold level set at 12-volts.