The SAE (Society of Automotive Engineers) connector standard is a family of all-weather low-voltage, medium current connectors.  It is defined by a standard contact form, spacing, and arrangement, and in certain motor vehicle applications, the purpose of each conductor is also specified.  For our purposes, suffice it to say that on the side of the connection that produces the power (battery side), the rubber-shrouded female conductor is the hot wire, going to the + terminal.  The most common place for an SAE connector in the life of the average person, is the connection used to plug in a trailer towed behind a vehicle, so the lights on the trailer work in sync with the lights on the car.  In motorcycling, the two-conductor version has been adapted by many companies as the standard power connector for 12V systems.  Among the companies supplying SAE power connections on their products are:  Aerostich, Battery Tender, CyclePump (sp?) and older Gerbing equipment.