A battery pack is configured to reduce weight, enhance battery identification, ensure proper placement of a lid retaining the battery, and facilitate battery pack removal. The battery pack has one or more cells that lack an outer coverage except for a polymer sheathing. The battery pack includes a mating notch on a terminal plate and may include a fingernail notch and/or one or more guide rails. The fingernail notch may be a single depression formed to allow a fingernail to slip onto the battery pack, may be a single depression and a ledge that are side-by-side, or may be formed of multiple ledges and/or depressions. There may be a single guide rail or multiple guide rails. Each guide rail preferably has a hollow interior section that is crossed by one or more ribs or segments.