Review on 🔌 PowerJive USB Voltage/Amps Power Meter Tester Multimeter: Accurately Measure Charger & Cable Speed, Power Bank Capacity by Charles Palma

Despite the very dark screen this is a great device that does exactly what it advertises. Plug it into a 5V charging circuit (typical of cell phones, batteries and solar chargers) and it will read voltage, amps and mAh. Multiply mAh by voltage and divide by 1000 to get watt hours. I use this as a small hiking solar panel (21W, 5V) while charging an Anker battery pack (16000mAh). I have found that the solar array is consistently outputting 5 volts at 1 amp at 2000 mAh = 10 watt hours. I also tested it and found that my iPhone X definitely charges faster when the battery is low and then slows down when it's almost fully charged. It was also useful for identifying which backup batteries were getting old and not charging as quickly. I suspect it might fail in a year or so, but even if it did, I'd buy another one for less than $10 for the utility of this little gauge.