Batteries for electric marine propulsion systems, and associated systems and methods are disclosed. A representative power system includes an enclosure having a first end and a second end opposite the first end, with each of the first end second ends including and inwardly-extending portion forming a handle region and having an opening into an interior of the enclosure. The power system can further include an electrical connector carried by the inwardly-extending portion and positioned beneath the opening of the second end, and at least one battery cell positioned in the interior of the enclosure and electrically coupled to the electrical connector. The system can still further include at least one fan positioned in the interior of the enclosure along an airflow path between the opening at the first end and the opening at the second end.