COOWOO USB Tester Digital Power Meter Tester Multimeter Current and Voltage Monitor, DC 5.1A 30V Amp Voltage Power Meter, Testing Speed of Chargers, Cables, Capacity of Power Banks

A great design - there are a few Chinese USB power meters on here with the same design; this one is decent enough quality and performed well on all the devices I've tested it with (iPhone, iPad, Raspberry Pi, various LiPo powerbanks, USB lights/lamps, etc). A great feature is that the USB male socket is reversible so that you can always see the screen regardless of the orientation of the socket in your power adapter/computer socket. I'm not sure what the longevity of the USB plug will be as it's very thin to accommodate both directions, but I've not had any problems. The backlit screen is nice and the operation is intuitive. A very handy gadget if you want to put your devices and power banks to the test (I wasn't happy that more than a few of my supposedly <2A chargers weren't putting out anywhere near that!).

Arrived well-packed in a strong, branded cardboard box, sealed with a branded sticker, and USB device itself was inside a moulded piece of impact foam, covered by a foam lid. Very good piece of kit for the price; Feels solidly built. No issues in use, although it takes a moment to understand the user guide and configure some aspects of the device (guide included attached to this review) as it is rather poorly translated into English. Especially liked the voltage on pins being shown so you can see at a glance if a charger is correctly "identifying" itself as a fast charger. Also has been quite an eye opener to see just how badly cheap "Poundland" cables can perform over official ones. Recommended. Only niggles would be lack of an included USB extension lead, as the device is quite wide and blocks adjacent USB sockets from being used on my own laptop, and a request for some sort of fixing in the case to allow attaching a lanyard or similar. That, or a nice slipcase for it would have been good. I'd have liked to see the USB plug retract into the body of the case too, as another idea for a future model.

I like the ease with which I can check the voltage and current the cable is providing to the phone or tablet but this can only check usb A to usb A port. No support for usb c and that mean not possible to check pd chargers who provide faster charge. So for my s10 45w and 25w chargers I can't use this. I think best suited for QC 3.0 chargers. I like to c the charger the new model support UsB A, C and micro Usb

Very useful device. I used it to check all my phone chargers and cables to identify which ones are capable of fast charging and which ones are fake. Just by trying every charger with every cable and watching the Wattage reading. Best combination proved to charge my Galaxy S7 at 12.3W (that's 9.15V / 1.34A). Most micro-USB cables I have cannot reach this speed. So not all cables are the same. Also the fast chargers are not the same either. Most fast chargers can only offer 5V and up to 2A max current. But in reality phone will restrict that to 1.5A (7.5W) or 1.2A (6W) or even less depending on cable quality (voltage sag). Some fast chargers are capable of negotiating higher voltage (if phone supports that) which speeds up charging significantly as above 12.3W vs 6W Also with this tester I can measure phone battery capacity when charging dead phone from 0% to 100%. The formula is W/h reading divided by 3.7V (battery nominal voltage). For example 10.000W/h / 3.7V = 2.7A/h. Of course this is not 100% accurate because some of the energy becomes heat. But if phone does not warm during charging then this method is fairly accurate. Sadly my meter had developed a horizontal black line across the entire screen already. Yet I cannot see any signs of damage. Suggesting this device is very fragile. Sadly

Very decent meter, it has indeed colour screen. I own the previous version from a couple of years ago and the main differences are: 1) The latest one has colour screen while the previous only B&W 2) The old meter has bipolar USB input connector meaning it does not matter how you connect it,it will output the correct DC polarity on the output 3) The new meter has much stiffer connector sockets so I guess much lower connectors series resistance so it should be a bit more accurate in voltage reading with higher currents...

3 stars given its now 2022 and not usb 3.0 compatible. Really nice bit of kit, clear and useful screen and being able to flip it upside down really helps too. I tested every usb in the house pretty quickly. Main issue I have with this is that it’s not USB 3.0 compatible. Sure you can plug it in a usb 3 port but it won’t allow usb 3 speeds or even the same power as what a usb 3.0 device would use. If you look at the plug you can see the 4 standard pins for usb 2.0 and below. Usb 3.0 has extra pins at the back inside the plug. This does not have those. Hope this helps as I was disappointed to have realised this after receiving, and had only bought based on a question the seller answered where they said it was USB 3 compatible.

If you're anything like me, and have a myriad of USB chargers, leads and devices, it can be frustrating when certain combinations don't work. This device takes a lot of uncertainty out of the process - at a glance it will tell you charging voltage and current, thus you can determine if kit is working as it should, and if not, possibly why not. As others have said, the manual is a feat of linguistic mutilation, however thankfully the plug-and-play nature of this presents useful information straight up with no fiddling required. Highly recommended.