USB detector 3.0 High voltage 4 bit OLED QC 2.0 Digital detector voltmeter ammeter voltage current power capacity tester meter (WHL #17)

New at Wan Hung Lo:

…wait, what?

(I’m pretty sure you’ll be able to find my address if you want to, just making it a little harder for google to index it as an image…)

So, what is it actually? Sure, it’s the USB power meter from the blog title. Who would have thought!
Bloody kids with USB 3 toys! Back in my days, we had…umm, good old RS-232 :lol:

I bought this one month ago at AliExpress for 8,61€ including shipping. As you can see, they decided to use some tracked mailing instead of the “ah, no worries” cheapo variant.
Now, have a look at the contents of the envelope:

Nice tin can (the spots aren’t rust…yet) that holds everything safe from external influences. The top part is actually a ~40cm wide 7-fold booklet with instructions:

Yup, not copying the entire Chinese manual for your pleasure. But I do for the Engrish one:

    USB Meter

Operation Instruction

To my dear customers
Thank you for purchasing USB Meter produced by Hangzhou Ruideng Technologies Co., Ltd. For quickly learn all function of our product to get good experience when using this USB tester. Please read this instruction carefully before you using this USB tester, and keep it when necessary.
Our tester can show either blue or white color on black background, you can choose any color you like.

Now that’s the main reason I bought the unit. User-defined font colors! (choose white or blue) ;)

Technical Parameter
Voltage measurement range: DC 03.70-13.00V
Current measurement range: DC 0.000-3.000A
Power measurement range: DC 0-39.00W
Capacity accumulation range: 0-99999mAh
Energy accumulation range: 0-99999mWh-999Wh
Voltage measurement accuracy: ± (0.2% + 1digit)
Current measurement accuracy: ± (0.8% + 3digit)
Update rate: 2 times/s
Idle discharge: About 10mA
Product weight: 14g (package 46g)
Product size: 64.0mmX21.6mmX11.2mm
Port mode: Compatibility USB 2.0 USB 3.0
Display screen: 0.91″ OLED screen

I have to say: I’m impressed! Even if the device misses these specs by a mile (tbd!), at least they cared enough to put all that information into a spec sheet. Side note: 10mA idle current may seem a lot, but remember the OLED unit from WHL #6. It had 1.5 to 22mA current draw depending on the amount of lit pixels, and it was about twice the area of the USB tester display. So 10mA sounds reasonable considering there is a little bit more going on under the hood to have voltage and current measurements displayed and capacity readings summed up over time.

Operating instructions
When connect power supply, the screen shows welcome window firstly and then displays current connection mode. Then it comes into the main interface. It has three Welcome window connection modes, direct mode, quick charge mode and disconnected mode (Only for USB2.0).
Direct mode is that the two middle signal wires are conducted directly. In this mode, USB port can transfer data normally. Quick charge mode is that the two middle signal wires are connected with the special charge chip. This chip can simulate quick charge agreement from different manufacturers to make different device matched automatically. So it can get quick charge. This mode can be compatible with more than 98% of intelligent device while the USB port cannot transfer data. Disconnected mode is that the two middle signal wires are disconnected. In this mode, USB port cannot transfer data.

Excellent! Reminds me of the WHL #4 debug adapter for USB – but it also should be able to carry USB 3.0 signals, which means devices can operate at their maximum speed, burning more energy than in limited 2.0 mode.

Mode Selection
Keep pressing the button first and then connect power supply. After the welcome window passed, you can set the three modes. When the mode you need appears, you can release the button. The mode selection is done when you see the LED flashes one time.
Current zero calibration function.
The component aging and temperature variation after long-term use may appear tiny error when it measures small current. To avoid this error, you can keep pressing the button on the back to connect power supply in the no-load terms, until the three modes passes (as shown in the figure),then the LED lights. The calibration is accomplished.

No auto-zero, but manual-zero. Don’t know if that says something about the device drift, but at least having such a function in the boot-up sequence is great!

When come into main interface, the first line displays voltage, power and data set. The second line displays current and accumulated capacity.
Over-voltage and Under-voltage reminding function
when the voltage is over 5.3V (less than 4.7V), the arrow will be flashing ▲ (▼)to remind the voltage is too high (low).When the voltage becomes to 4.7V-5.3V,the arrow will be disappeared.
In the main interface, you can click the button to switch data set one by one. And it provides for storing and checking 0 to 9 totally ten groups data set.
Capacity stored function
When data set is between the 1 to 9 group, the current capacity will be stored after power off.

Okay, so the guy with reasonable English writing skills just went home after his short 20 hour shift, but his colleague went on with translation. Well, I guess one does understand what they mean, but the klemping really ticks me off. I know the Chinese are prone to do this, but c’mon, proofreading just once would have fixed it…

And the stored capacity will be accumulated after power on. When the data set is 0 group, the current capacity will be stored after power off. When power on next time, the stored mAh is blinking displayed . When the new mAh is up to 1 mAh, the stored mAh will be covered, and the values will start over.
In the main interface, double click the button on the back (the time interval of the double click is within 0.5s), then you can get into the data check window and see the capacity of the current data set. In this window, you can click the button to check the next data set, and when you keep pressing the button more than 2s, the current data set will be cleared. And if you double click the button, it will come back to the main interface.

Still dunno why you need ten bins for your capacity data, but hey…they clearly had free space in the microcontroller ROM and RAM for that. And also thetranslator guy switched from klemping to plenking. Oh well.

Capacity unit switch function

In the main interface, keep pressing the button, until the LED lights (time about 2s), release the button, the capacity will be switched between mAh and mWh.
Screen rotation function
In the main interface, keep pressing the button, until the LED lights and then goes out (time about 4s), release the button, the screen is rotated and automatically stored for being used next time conveniently.
Shut-down screen function
In the main interface, keep pressing the button more than 6s, then release the button, the screen display can be shut-down and come into power saving mode. The LED is flashing in this moment and you can click the button to come back to the main interface.

Moar features! This time, quite nice ones. I wonder what the current draw is in the display-off mode. And I wonder what happens when pressing the button for 8 seconds…a game of tetris, maybe?
Anyway, that was a helpful manual indeed, as one would have spent quite some time figuring out the individual button press lengths and their corresponding effects. Now let’s have a look at the device itself:

Actually, that’s very nice packaging. The padding has excellent fit and the tester is absolutely safe in there. Well, I’ll throw away the goofy handle asap (it disintegrated already…), and maybe the cap won’t be there for long, but the rest is good stuff!

Of course I couldn’t resist peeling off that wanky sticker on the back of the device. Yup, it’s a lever moulded into the case, with some air gap around. Dirt will find its way, for sure. And I think one cannot open the case without destroying all the hooks, so I won’t bother taking it apart for now. A shame.
I also cannot tell much about the insides. The chip besides the button has some sort of fake-ish ST logo on it and probably says “GZ547”. Google doesn’t know about it, neither do I. Good luck finding a generic “547” part that is not a BC547 :) On the back, there is nothing to see from above, as the OLED covers much of the center of the PCB. There is at least one more 10-pin device present. I’m not sure if that is the display driver, as the OLED is really really thin and there is no bulge on the two glass substrates. But maybe the driver circuit is the black strip on the upper glass plate and they managed to do some very delicate chip on glass mount. That aside, the current shunt is clearly visible, it’s a 10mΩ SMD part.

Put the puppy under some load!

Voltage readings are great. To cite the specs:

Voltage measurement range: DC 03.70-13.00V
Voltage measurement accuracy: ± (0.2% + 1digit)

Ah well, she’ll be right. For a pure USB gadget it should be spot on at 5 volts, not the center of the allowed supply voltage. But who cares about the last digit.

Current measurements are however a bit of a problem for me. I do not own any precision current sinks (or sources) and I need to rely on known resistors under known voltages. Voltages are okay as seen in the above image, but resistors..meh. I have the Half Ohm for precision measurements…for up to 3 Ohms. That’s a bit of a problem when I want to try values up to the maximum allowable voltage AND stay below the 3 amp rating. So I decided to use a 12Ω, 17W power resistor from Vitrohm that I have in stock for some 12V/1A measurement. It reads (12.4±0.2)Ω on bare terminals, spec is ±10% (yawn). Combine that with some short USB plug to connect to the USB tester, that’s more like 12.6ish Ω.
But: There is a temperature coefficient, for sure. Won’t do that much under light load, but if you sink the rated power, you’ll have to take that into account. Vitrohm says (I’m astonished): Temp Co? Nope. 0 for every 17W type (KV218) in the 1R8 to 2K4 range. Well, ±40 ppm per K uncertainty, just to be sure ;) So basically one would not expect the resistor to change values, just half a Milliohm per Kelvin. Great!

Sinking 0.386A at 4.72V means 1.82W dissipation in DUT and cables. The unit shows four significant figures because it can. Just forget about it.
I did run that test for half an hour and temperature on the resistor got up from 20°C room temperature to 51°C. Which means ±15mΩ due to the temp co, but the reading was rock stable the entire time. The current reading on the lab power supply also never changed. But: That’s only 12.2Ω load resistance. Not totally off track, but we might be out 4% in the current reading. However, for my crude measurement, that’s basically within uncertainty…
Another side note: Heating 31K above ambient temperature with 1.8W isn’t too far off the claimed thermal resistance of 15K/W, especially when considering that this is for freestanding units in vertical mounting position…while mine heats the table. That’s however not included in the nice derating fact sheet from Ohmite. 17K/W sounds fine for such an application.

Wanna see how crude my measurements are? Here we go:

That’s the improved test setup for the second run. I decided to ramp up the voltage but keep the resistor. I didn’t find a suitable one to sink more current and have lower resistance to reach that goal inside of the 13V voltage cap – the array in the background was too low in resistance as both resistor types are paralleled up for basic stress testing of ATX power supplies.
Red and black cable from the lab power supply go to my USB dev board, which supplies the USB tester, which supplies the water-cooled resistor via an USB adapter made from some Arduino breadboard connectors. One side note about the water: That was clear tap water before the test. Half an hour later, at the time of this picture, it didn’t look very appealing to me. And there was some blue junk coming off the resistor as well, which now has some corrosion problems. After I took it out and cleaned it, one of the legs broke off. Must have been a hell of a ride for him… :twisted:

The glass of water aside, the rest of the setup was identical. So I twisted some knobs and ended up with 0.966 amps at 11.58 volt. Which is 11.18 watts of dissipation into the tap water. This time, current slightly increased over the test duration to 0.977 amps, which is 1.1%. That’s clearly beyond the 0.05% from the resistor temperature coefficient (the brine actually went up from 20°C to 32°C), so one has to ask what has happened.
I’d say it was the tiny connecting cable to the resistor, but rising current means declining resistance when at a stable voltage…so cables causing more resistance are going the wrong direction. We also know that the temp co is basically zero up to 50°C, so it can’t be a negative coefficient that counterbalanced the wire resistance, as in the previous tests we had more heating at lower current. That would totally contradict this result. Anyone wants to guess what has happened? Beats me right now…

For both runs, I recorded the capacity readings after 5, 10, 15 and 30 minutes, so that I can compare against the other readings. For the first test, this was 152mWh vs. 152mWh (spot on, obviously), 305mWh vs. expected 304mWh (I won’t bother calculating that 1/300th difference to enough significant digits and then calculate my expected errors on that…), 458mWh vs. 456mWh and 915mWh vs. 911mWh. So the device sums that readings very nice and the clock is also working very well ;)
Sames goes for the second one: 952mWh at expected 933mWh, 18882mWh->1865mWh, 2827mWh->2798mWh and 5672mWh->5595mWh. Yes, there is a noticeable difference, but the expected values are calculated with the power at the beginning of the run. Plug in 0.977A instead of 0.966A and you’ll end up with 5657mWh after 30 minutes. 0.3% off – perfectly fine result. But maybe the rise in dissipated power over time is a hint for the discrepancy described before…

The low/high voltage indicator is just a software option that kicks in at exactly the claimed values. And power reading is exactly voltage times current reading, so no surprises here.

Well, what else to check? Idle power consumption!

As expected from the datasheet – “about 10mA”. The DMM only has ±0.8% and 3 digits accuracy – so we’re good here, even though I cannot present exact numbers.

What about the promised reduced draw when the display is off?

2.5 to 4.0 mA – that’s a nice reduction in power draw! Don’t be fooled by the LED…the DMM lags behind severely. So it’s not that the tester draws LESS current when the LED is on…I’ve checked, I had the same WTF face once is saw it on the photos. But really…if your device can operate on 2.5mA…why add a frequently blinking LED that draws additional 1.5mA or 60% when it’s on? Surely there are low-power types available and your BOM wouldn’t explode when adding another type of resistor to get the power draw down. Geez.

One last thing: Display update rate. Like with the SPI-OLED, you can clearly see individual refreshes when moving the device relative to you:

These images were taken with 1/30, 1/30 and 1/10 second exposure. You can clearly see a blanking period between the screen refreshes. In the first two images, one can count 6 and 7 individual lines, translating to 180-210 Hz refresh. The 1/10s one has..19? individual images, which is 190 Hz. So I’d round to 200 Hz refresh rate. Very noticeable to me, maybe some folks don’t see it. But as this is just test equipment and you don’t look at it all day, it’s okay. When taking photos at normal exposure rates, that’s also no problem. See the following ones in a real-world application, where I hooked up some Sandisk USB3 flash device:

Conclusion time!
I think it’s an excellent Wan Hung Lo product and I would buy that again. It’s not total trash, so it is usable in everyday situations and one can have a certain amount of confidence in the readings. Especially for USB devices, one just needs a rough estimate on voltage levels and power consumption, so this puppy does alright. It also offers USB3 data signals, so your devices can operate under full load, which is great (USB type-C rubbish, here we come…).
On the contrary, the firmware is a bit wanky with 9+1 reading bins that are fiddly to empty and you have to cycle every time you accidentally push the button. Speaking of the button: One or two more buttons would have been great, so that you don’t need the manual for reference handy in case you messed something up (the screen flip mode is still a great feature!). The manual and the fiddly menu are also the main reason this unit isn’t really ready for the European market, as Jon Doe would be a little swamped with it. Yet, for 8€, that’s an excellent Wan Hung Lo product for tech people that can handle a little Chinglish.

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