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 (mW), Total Power (mWH or mAH), and Time Elapsed Specifications Limits: 0-50 Volts, 0-5 Amps, 0-250 Watts, 99999Ah Resolution: 0.0001V 0-50V 0.0001A 0-5A Error: +/- less than 1% (less than 0.2% upto 2A) Battery life: Approx 20 Hours, 4 stage battery meter Backlit LED screen can be seen at night or bright sunlight. Light switches off after 10 seconds, can be turned back on by double tapping the time/power button. Pause/Reset buttons to store the total power and time readouts.