Onion peel is one of the solid waste produced either from the onion processing industry or waste from household waste. Onion skin contains cellulose compounds that are quite high, which is 41-50% as well as aromatic compounds. It is underlying that onion skin can be used as a raw material in the manufacture of activated carbon. One of the uses of activated carbon is as an adsorbent in the conditioning of pH and TDS levels in battery water waste. The manufacture of activated carbon is carried out with 3 main stages, namely carbonization with a temperature of 400oC for 1 hour, sorting particle sizes of 10-16 mesh and 60-200 mesh, and variations of NaOH activators of 10%, 15%, and 25%. Other variations used in the study included the use of 12V/100W floodlights in the purple, yellow, and no lighting spectrum, as well as an active carbon mass of 0.5 and 1 gram. The best adsorption rate is obtained with variations in activated carbon 60-200 mesh, activated carbon mass against a solution of 1 gram, and with purple lighting with a wavelength of 380-450 nm where the initial pH 2 and final pH of 4.8 and TDS decreased by 180 Ppm where the initial TDS is 9,690 Ppm and the final TDS is 9,510 PPM and has the potential to produce hydrogen.