Due to the critical nature of the energy storage systems, eliminating wiring errors is key. The Han^® S provides two features to ensure just that. First, the housings and plugs are color coded so that there is a quick and instant visual indicator of the positive and negative pole. The red color indicates positive, and the black color indicates negative, as traditionally known in the industry. The second feature is an additional safeguard against mis-mating. The positive and negative connectors are physically keyed such that they cannot be plugged into each other. These two features don't just mitigate errors, they eliminate them.