USB Type C Tester Meter - Digital Multimeter Amperage Power Capacity Reader, Current Voltmeter, Voltage Monitor, Amp Charging Detector Checker DC 0-30V/0-6.5A

Exactly what I needed: a low-priced way to test chargers and cables to see if they support USB-PD. In this, it rates 5 stars.I didn't need--and am not evaluating--a rugged device for the everyday use of a design engineer. I didn't need--and am not evaluating--a precise and well-calibrated meter to design, test, and/or operate mission-critical equipment. I didn't need--and didn't test--its more advanced features (e.g., amp-hours). I used it only to look at Amps and Volts in real time--which is the best way to test chargers and/or cables.And for that--testing chargers and/or cables--this is an awesome little gizmo at a great price!The problem it solves: there's no good way to quickly tell how fast an iPhone is charging without an external meter. There are a few apps that claim to do this, but all they do is watch battery percentage and do a little math. Which is both slow and unreliable.And--like other reviewers have noted--most USB-C-to-lightning cables don't support fast charging, even if they claim to. Want to know for sure? Use this meter.To test cables and/or chargers to see if they will support fast charging: watch the meter voltage. If/when it shifts to 9(ish) or 15(ish) volts...it's fast charging. If it stays at 5(ish) volts...it's not. It's really that easy.This meter doesn't seem to interfere with the feedback loop that enables USB-PD. I used it with multiple phones and chargers, and it worked great. I had good success with the Apple brand USB-C to lightning cable, but not with any others.An important caveat: the battery must be relatively depleted for fast charging. The iPhone charges to a "soft landing" at 100%, and slows charging as it approaches fully charged. This is why Apple claims "up to 50 percent battery in 30 minutes" instead of "fully recharges in an hour".<Brief Explanation of USB-PD>USB has become the "universal" power jack to recharge fill-in-the-blank. That's nice when you need to recharge, but not-so-nice when you need to quickly recharge. Charging needs watts--volts x amps--but the most you can get from a USB jack is about 10 watts. This is because cables and connectors can only handle about 2 amps, and regular USB only puts out 5 volts.But what if you could somehow jack up the voltage? If you could quadruple the voltage, you could quadruple the power--using the same connectors and cables!That's the concept behind USB Power Delivery (USB-PD), an open standard embraced by Apple to charge the newer generation of MacBooks and MacBook pros (that need WAY more than 10 watts of power!) with just a USB-C port. And Apple also (with very little documentation) began supporting it for the iPhone beginning with the iPhone 8.In all of these devices, if/when a USB-PD charger somehow gets the message that the attached device is compatible, it'll kick up its voltage to 9 volts, 15 volts, or even 20 volts...and the device will charge much faster.But "somehow gets the message" is really, really important--as it would pretty much fry your stuff to hit it with 4 times its design voltage! And since it's bad for business to fry folks' stuff, any decent charger will limit itself to the good old 5V standard unless the attached device clearly tells the charger--through the charging cable--that it can handle the higher voltage. Which means that the charging cable matters as much as the charger.</Brief Explanation of USB-PD>

Was testing my mobile phone power draw had to take it out of its case which was a minor issue the it worked perhaps a little longer connections

This is very useful to test just about any USB charging device/cable and also battery capacity. I mainly used it to test USB-C to lightning chargers. It is well worth the price since you can weed out bad cables/chargers to make sure you are getting the fastest possible charge. It is very accurate on the input side. When a load is connected however the output voltage reading is about 100mV high most (but not all) of the time as tested concurrently with a multi-meter. This really is not that big of a deal since you should be more concerned with the current going into the device- and in this regard it is very accurate (also tested with multi-meter). I have two other USB meters and they both show slightly different readings (input and/or output) as well so this is not unique to this device. I will however probably use this one most often since it has a micro USB input which is great for testing cables. The device is a bit flimsy. I would not recommend letting this thing hang off the wall from a power adapter. Try to put as little stress on the device as possible using an extension cord and something to brace the meter during readings. There is no manual. I had to use YouTube to figure out how to fully use the device. It involves rapidly clicking the button between 1-5 times for various adjustments and holding down the button during power-on to adjust some settings. After testing many different devices my best tip is this: if you want the fastest possible charge- always use the shortest charge cable you have and never use "flat" charge cables (just throw them away..trust me).

Other than voltage all of the readings are a mystery. It seems to be bi-directional as the in and out labels aren't correct.

Works great for what was needed of it.