As a reviewer who is constantly testing external batteries I have a need for a product that can help quickly and easily determine if the various USB ports on a power bank deliver the output they are rated to, and the capacity is as it should be. Now this previously was done by plugging and unplugging various tablets, phones and devices until I could drain the battery, confirm it tested but I was just using device testing without any actual measurements.
So I bought the DROK Digital Multimeter USB Port Tester and found this to be an extremely valuable product if you happen to be in the business of needing to test a lot of external batteries, or want to make sure what you buy is delivering what you expect it to.
This USB Digital Multimeter plugs into a USB charging device, and then you plug your mobile device that you are charging into it and it will read and show you in the OLED display the voltage output, mAH output and the capacity that it detects in the power bank based on how much is passed through it. Now, when testing AC outlet chargers the Capacity measurement is irrelevant and inaccurate since there is no fixed capacity for an AC wall outlet, so this reading is not usable at all and will forever increment.
But it was spot on with showing the amount of draw that a tablet draws from the USB power bank or the USB AC Power station. It confirmed that many 2.1A devices don’t actually draw the full 2.1A when they are plugged in, and while the Kindle Fire HDX 8.9″ draws 1.75A while charging, the Kindle Fire HDX 7 draws about .75 A when it charges. It will also show how many watts are being pulled to charge the device, and you can see in the above picture 8.7W are being pulled to charge the Kindle Fire HDX 8.9″.
What I like about the device is sometimes you have to plug it into various directions of a USB Power Bank and the button on the back will reverse the display so you always see the data without having to rotate the device upside down. It also stores in memory the last reading so if you unplug the device and plug it in without something charging you can see what the last reading was to write it down if you need to. It has over and under voltage detection with warning arrows if you get something providing lower than 4.7 volts, as is accurate to within 1/2 a percent.
Not many people may have a need to have a Digital Multimeter USB Port Tester, but if you do then I highly recommend you get the DROK Digital Multimeter USB Port Tester as it does a fantastic job and help you make sure that power bank or even if you need to test your USB cables and make sure the cable isn’t having some issues where it isn’t delivering proper power. I have had USB cables fail previously where an iPhone wouldn’t charge with one USB cable but it would with another lightning cable, and if I had the DROK Digital Multimeter USB Port Tester at the time I might have been able to determine what was wrong with the cable to confirm it wasn’t supplying enough voltage or enough amps.
When testing the capacity through the Power Bank, really it increments as power is drawn from the power bank, so you do still have to have devices fully drain power bank to 0 to see just how much capacity was passed through the DROK USB Port tester. In the cases of 12,000+ mAh power banks, this can take a long time to drain test an external battery but it gives you pretty accurate measurement if the capacity of the battery is what the manufacturer stated. On the other token, it also tells you how much capacity the receiving device has if you let it drain then fully charge through the DROK meter, you will see how much capacity it took to charge it therefore inferring the size of the battery in the receiving device as well.
Anyway, this is a 5 star USB Port Tester and highly recommended if you want to test the power output of your USB chargers.