Review on 🔋 DROK DC Voltmeter Ammeter Panel: OLED Digital Multimeter with Run Time, Temperature, Power Capacity & Battery Testing - 0-33V 3A, 0-99h59min, 99W, -15℃ to 60℃ by Mike Swanson

Great product. It's a bit small but for the price I don't think it's a valid complaint. Functionally it does everything it claims to do and is fairly accurate based on two separate DMMs I tested it against. I connected this (7 in 1 multimeter version) to a 750mA charger just to give me information on what voltage and current the charger is outputting at any given time. As a bonus, it also allows me to keep track of exactly how long the charger has been on and how many Ah the charger has theoretically transferred to the battery (although, of course, batteries aren't 100% efficient at storing the energy you put in a battery ). them when loading, so it's really just the upper limit). I also love that the display can be powered from any voltage between 4 and 20 VDC, meaning I could just pull any wall wart out of my big box of discarded wall warts, strip the ends of the wires and connect them. No need to look for one with the correct output voltage. I will probably buy more of these in the future.