The implementation of lighter and smaller power sources requires the estimation of power demand under different driving conditions, which are not available for portable assistive technology such as electric or power wheelchairs. Power demand estimated through power and driving cycles is a common methodology in the automotive industry and critical for sizing the power sources. This study determines power and driving cycles in simulated standard outdoor conditions adapting the microtrip methodology. Power consumption and distance travelled were calculated for five different tasks (longitudinal slopes, cross slopes and a flat surface). A “typical” wheelchair journey is presented as a suggested representative drive cycle. A numerical estimation of the power cycle is compared to the experimental results. The difference between numerical and experimental mean and maximum power is 7.58% and 1.07% respectively. Ascending longitudinal slopes were characterized by significantly higher mean power consumption compared to cross slopes and the flat surface. A theoretical fuel cell implementation is presented. The powertrain has a 160 W fuel cell and 470 W battery with a 27 gH2 metal hydride canister that increases the 30 km original range of the deep-cycle lead acid batteries of the electric wheelchair to 521 km.