Review on 🚗 Dual USB Car Charger with 4.8A Output, Voltage Meter, Compatible with Apple iPhone, iPad, Samsung Galaxy, LG, Google Nexus, and USB Charging Devices - Black by Chris Shepherd

I ordered this to monitor the bus battery level in my motorhome. The USB connections seem to work fine, but the voltmeter differs from two professional voltmeters by more than 0.1 volts. (It reads 12.5 volts when it's actually 12.73 volts.) You may not care, but I do. That's the difference between a battery being 60 or 70 percent, or between 90 and 100 percent. Even my cheap handheld multimeters are much more accurate than these.