Good battery pack design must take into account many important factors, and often must satisfy seemingly conflicting requirements. A well-designed battery pack will seamlessly enable full functionality of the portable device it is paired with, and be able to keep it running for an acceptably long time between charges. Portable devices can be subjected to a wide range of different usage parameters and physical environments, all of which must be allowed for within the battery pack design. To achieve these ends within allowed size, weight, and budget constraints, a whole range of possible options must be worked through, and the most desirable and appropriate solutions identified and incorporated into the single, final design. 

In addition to good design, the other elements essential to production of a successful battery pack are materials and assembly: both must be of the highest standard to ensure that the battery can physically and mechanically withstand the full range of harsh treatment it may undergo during its service life. When the internal cells finally fail and the battery pack needs replacing, it should still be in top condition mechanically.