Hati hati gan terkena kasus HKI, https://www.academia.edu/30478634/DOKUMEN_PATEN_HELMCHARGER_TENAGA_SURYA https://www.academia.edu/30074736/PRELIMINARY_STUDY_ON_MAKING_CHARGER_HELM_HELM_GENERATING_ELECTRICITY_USING_ SOLAR_ENERGY_DC_PHOTOVOLTAIC_AND_WIND
