YOJOCK USB C Tester USB Power Meter 2 in 1 Digital Multimeter 3.6-32V 0-8.0A Voltage and Current Tester, Type C Voltmeter Battery Capacity Volt Ammeter Power Bank USB Cable Charger Detector

Works great, nice quality

This has become a mainstay of my product testing arsenal. Easy to use, clear information, and multiple connection methods makes this tiny little thing capable of all kinds of USB based testing.I primarily use it for verifying the capacity of usb power banks as well as usb solar panels (since there is often no way to see what rate you're charging at without one of these)Be aware that there are conversion losses in the banks themselves. a 10k mah (37wh) battery SHOULD take about 42Wh to charge, and provide around 32Wh usable capacity for example. Some cheaper usb battery packs will rate their capacity based on the amount it takes to charge them as opposed to the actual capacity and this helps shine a light on these cases of corner cutting that your average buyer would have no way of testing while being close enough that they don't doubt the honesty of the rating.

This was delivered on time. I misunderstood a few things in my testing and the manufacturer was quick to respond to my questions. I believe that I tested every J7-c configuration. While I cannot vouch for the accuracy - it did what I needed - I can state that everything worked. There are some limitations in the device, but more on that below. Most of the limitations seem to be due to destination plug standards.USB to J7-c to USB to lightningInput - I tested this with both a powerpack and plugged into the wall chargerOutput - to a magnetic charger for an Apple WatchResult - perfectUSB to J7-c to Type-C to lightningInput - I tested this with both a powerpack and plugged into the wall chargerOutput - to a iPadResult - perfectType-C to J7-c to USB to Apple magnetic chargerInput - I tested this plugged into the wall chargerOutput - to a magnetic charger for an Apple WatchResult - no output, however, the manufacturer told me of this limitation:"Apple devices don't support charging like this because Apple’s charging system is strict, it with a charging identification chip. If you use this usb tester to test Apple devices, it only supports Type C-Type C-lightning or USB-USB-lightning or USB-Type C-lightning."Type-C to J7-c to USB to miniInput - I tested this plugged into the wall chargerOutput - to a GarminResult - same as last test, probably due to same "standards" limitationType-C to J7-c to USB to microInput - I tested this plugged into the wall chargerOutput - to a powerpackResult - same as last test, probably due to same "standards" limitationType-C to J7-c to Type-CInput - I tested this plugged into the wall chargerOutput - to a iPadResult - perfectMicroUSB to J7-c to USB to USB micro to a powerpackInput - I tested this plugged into the wall chargerOutput - to a powerpackResults - SuccessMicroUSB to J7-c to USB to Type-C to a magnetic charger for an Apple WatchInput - I tested this plugged into the wall chargerOutput - to a magnetic charger for an Apple WatchResults - SuccessMicroUSB to J7-c to USB to USB mini to a GarminInput - I tested this plugged into the wall chargerOutput - to a GarminResults - SuccessMicroUSB to J7-c to USB to USB mini to a magnetic charger for an Apple WatchInput - I tested this plugged into the wall chargerOutput - to a GarminResults - J7-c showed input power level, but no output power createdIn summary,a) the J7-c with USB input worked great for all output types I testedb) the J7-c with Type-C input worked fine when the output was Type-Cc) the J7-c with MicroUSB inputd) J7-c use with Apple Lightning can be problematicThis fits my needs now that I know the limitations and I recommend this to other users.

The display is somewhat small. If you are trying to show lots of different parameters this forces the text to be small as well. Fewer parameters allows larger fonts to be used. You can scroll through the screens until you find one you like. Display is also multicolored which is nice.

Convenient since it can show voltage and current for USB-A or USB-C. I learned that the Apple 20W charger, which is rated at 20W, puts out 5V if I plug the charging cable into my iPhone 13, but if I use the Apple magnetic charging puck, the 20W charger puts out 9V.

Records both Wh and Ah and many vital metrics. Memory is retained even after power off.

This is just as useful as the cable testers, except for the chargers instead. Stop guessing if that wall wart is 1A or 4A, or have to break out the microscope to read the invisible specs on the side. Just plug it in to this and then to the device you want it to charge. Instantly know exactly how many watts it can put out, or if it supports 9, 12, 15, or 20V for various levels of fast or laptop charging. Once you have a baseline for a charger, you can even start using various cables in between to check if they support the power requirements themselves or if they are forcing the charger or device to drop to a lower current or voltage than they're capable of (yes, this happens). You can quickly identify trash-chargers, organize them by the power they'll support, or just generally troubleshoot if a device, charger, or cable is bad, incompatible, or just flakey. I love this stupid little gadget. Almost as much as the cable tester.

The multimeter arrived when promised and was as described. It tested out just fine. I would recommend it to friends.