Cells of a prototype powered wheelchair can be designed in various connections to provide different supply voltages which has impact on the efficiency of other wheelchair drive ele-ments. The impact of cell configuration and resulting battery voltage on overall efficiency of power elements have been studied to determine the optimal configuration and voltage of the pack. A brief description of a battery energy storage system was given, and main re-quirements and variables were introduced to reveal the flexibility of the battery design. The efficiency versus supply voltage plots of a drive converter and battery charger were pre-sented and discussed to find the optimal battery voltage. The motor design was analyzed from the fill factor perspective. The calculated efficiency parameters of all drive power elements were used to discuss and select an optimal battery cell configuration.