Review on AINOPE Car Charger Adapter, Dual QC3.0 Port 6A/36W USB Car Charger - All-Metal Cigarette Lighter USB Charger with Voltage Display - Compatible with iPhone 11/11 Pro/XR/X/XS/8, Samsung Galaxy Note 8/S9/S10+/S8 - Silver by Jacob Kuntz

I bought this to charge two phones at the same time and also to know what voltage my battery is when my car is off. When I first plugged it in, it turned on immediately and displayed the correct voltage. However, as soon as I connected my phone to it, everything went wrong. It started flashing numbers from 0 to 90 volts. When I looked at my phone, the lightning bolt icon was blinking on and off. I love the idea of this handy little tool, but it just doesn't work right away. Maybe I have duds. Update: A replacement was sent and works as it should. It still shows random numbers, but I believe that's what's draining the battery. I have no idea because there were no instructions for it. Therefore four and not five stars. It still does its job as a dual USB charger that charges very quickly.