In situ monitoring the healthy state of energy storage devices is a smart way to avoid severe accidents and major emergencies. Electrochromic supercapacitors (ECSCs) stand out among other devices owing to the smart color variation during charge and discharge processes. However, it is hard to obtain the precise state of charge via only identifying their color change. To address this problem, an integral system composed of the inorganic CsPbBr3 perovskite photodetector (PPD) and polyaniline (PANI)//WO3 ECSC is proposed here. The PPD can simultaneously collect the variation of responsive current (under a green laser with the wavelength of 520 nm) when the ECSC is being charged or discharged. The real-time state of charge following the color change can be recorded by the PPDs constantly and accurately. A voltage alteration as small as 47.2 mV (charge variation of 0.33 mC) can be detected by this integral system rapidly, implying its great potential in managing the health condition of ECSC or even common energy storage devices in the future.