The monitor is useful for a wide range of uses: it can help you angle a solar panel to capture the most energy, as a DC power analyzer / watt meter to see how much capacity a battery pack really has, how much energy it takes to fully charge your devices, test your household or car batteries to see if they are close to dying, and test your USB cables to see if they are causing slow charging.Shows readings in Volts (V), Amps (A), Power (W), Total Power (mWH or mAH), and Time ElapsedPlease ensure all cables / adaptors are firmly connected otherwise the monitor may not show the voltage figure.SpecificationsLimits: 0-50 Volts, 0-5 Amps, 0-250 Watts, 99999Ah Resolution: 0.001V 0-15V, 0.01V 15-50V, 0.001A 0-5A Error: +/- less than 1% Battery life: Approx 12 Hours, 4 stage battery meter