In the present work, firstly, biocarbon is synthesized using unexplored biomass from Aerva lanata waste and applied for supercapacitor applications. Secondly, a critical question of interest, the assessment of the charge–discharge behavior of supercapacitors during the transition from laboratory to commercial-level biocarbon load, has been addressed. Thirdly, a comprehensive evaluation of electrochemical equivalent series resistance (ESR) for charge–discharge cycles during this transition has been reported. The single electrode-specific capacitances of 298, 265, 126, 55, and 50 F g−1 were found for the supercapacitor at 0.1 A g−1 with biocarbon loadings of 4, 10, 20, 40, and 50 mg cm−2. The specific energies of 14.7 and 13.0 Wh kg−1 were obtained at 0.1 A g−1 for 4 and 10 mg cm−2 biocarbon contents. ESR increases from 2.5 to 6 Ω cm−2 at 0.1 A g−1 on increasing biocarbon loading from 4 to 50 mg cm−2. Interestingly, in the high-mass electrodes, ESR decreases when specific currents are increased, as a result of charge redistribution and improved wettability. During the long-term stability test, a 30% increase in the specific capacitance was measured with a thick electrode due to improved wettability and reduced ESR value on continuous cycling.