A tale of 3 USB Testers: Ruideng UM25C, UM34C and a fake
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- Опубликовано: 21 авг 2024
- Ruideng makes a number of well known USB Testers. I have reviewed their UM34C before. This video started as a review and tear-down of the Ruideng UM25C but when I saw the UT25 which is a poor copy of a UM25 dressed up to look as different as possible, I could not resist. And so this video became a review and comparison of 3 testers and quite a bit longer than intended.
If you are only interested in a review of the (genuine) UM25C, I made a shorter version that skips over all the other stuff. The shorter video is here: • Review and tear down o...
My original review of the UM34C: • Review and tear-down o...
it's ABSOLUTELY the best video regarding usb testers!!! It's school example how it should be done!!!
Please note: a lot of people sending me comments with links in them. These comments are removed by RUclips automatically and I have no way to reply. The frustrating thing is that I can see your question because I get them as emails as well but I can' t reply as much as I want to help.
Great review! Thank you! I considered USB Testers and decided (because of their burden voltage, limited information output and questionable accuracy) to go with a simpler solution... I built my own USB Tapper. This is a PCB board that allows you to investigate the four lines of USB (Power-Rx-Tx-GND) easily, with your own test equipment. The Tapper is used with a single DUT, or inserted in between two USB devices. From one side of the board to the other, the arrangement is as follows: USB Connector - Individual Test Point Loops on each of the four legs - Jumpers on each of the four legs - Another set of Individual Test Point Loops on each of the four legs - Another USB Connector. So, with the jumper left in place, the test gear may be inserted in parallel to any, or all, line(s). If the jumper(s) is removed, the test gear may be inserted in series to any, or all, line(s). Additionally, while the jumper(s) are removed, activity can still be monitored on each side of the break with the Test Point Loops, or data may be injected, etc. I hope my description is clear. If not, please ask questions. I ordered PCB boards, but it can easily be made with "perf" board.
That's a great solution. I am using something like it myself but is far less advanced than your version. You may have seen it in some of my USB-tester related videos. Its a small black box with a USB connector and socket on each side and 4 banana sockets on the top with VBUS interrupted for current measurement. I think I showed the (very hacked-together) inside in one of my videos, but I can't remember which. I am using it like you for monitoring USB voltage and current using "proper" multi-meters. For testing the TC66C, I just ran 5 amps through it and it gets toasty. Can only do it for a few seconds or the internal wiring starts glowing.
The WHOLE idea of a stand-alone USB tester like these is so you don't have to go to all that trouble for something that really doesn't need to be any more complicated or accurate.
It is the same as for USB loads - of course you can spend hours making up some complicated. test rig and connect the DUT to a laboratory load, but that is not needed to perform reasonably comprehensive tests.
The portable devices allow people to test without ANY additional equipment, and they can be slipped into a pocket or toolbox, and transported to remote locations rather than needing the DUT to be brought back to the lab.
The reality is that all you need is a way to verify voltages under various loads - how many amps can you pull before voltage drops below (say) 4.9V?
Very good video! You clearly spent a lot of time making it. Great job!
thank you so much for making this good testing video, it is very useful
Ruideng RDTech should hire you either a brand ambasador or a consultant
The chip marked CASP (CAQD) should be MCP3421 18-bit ADC. It also has PGA with gain up to 8. Pinout matches exactly, and topcode matches too. With useful resolution of 17 bits (only positive values are used) and max gain of 8 you get 0.2mA resolution without any oversampling. Which matches what I see, because current tend to stick to 0.2mA increments for me. It still oversamples some, because you can occasionally get it step by 0.1mA.
Chip marked A810 is just a switch, I think it switches between voltage input and current shunt. It should be SGM3157 on a clone (Maybe some better on the original).
The clone has the same chips, just the resistor is low spec, that explains why clone has no temperature drift on voltage, but big drift on current.
That is a very helpful investigation. Many thanks
got what i needed tysm
ty for posting and sharing
Good testing. I have both the real and fake one,. Bought the fake as real one wasn't available at the time from Chinese vendor I usually used and paid the higher price on eBay of over $35 and was a fake, so opened a case and returned it and next time bought the fake on purpose for $17 bucks from a more honest seller as figured I try it and needed a couple of USB testers anyways and ordered the real one on Banggood with long processing time, so bought the fake as well on eBay so I at least could have have one tester while waiting for the real one to show up from slow boat from China. Did had to do some clean up, but both are pretty close pretty much dead on within specs even in current measurements. So may have just received a better batch of the fake, as mines had the Bluetooth option as well.
This was really informative. Is the um34c still worth buying, or should I purchase one with type c? I'll mostly be using it for checking power pack capacity. Thanks.
Unless you have special reasons to go for older USB standards, I would go straight for a good USB-C tester. There are plenty of cheap adapters and cables that allow you to use a USB-C tester with USB-A, mini and micro-USB with no problems.
wow, what a great video, didn't expect such a quality analysis, left no questions open!
Especially the automated testing over the hole current and voltage ranges were amazing!
What is the micro USB jack on the side for?
is it at any chance to supply the device with an external power source, I thought I read something along that on the ruideng site.
Many thanks. As far as I know only the TC66 can be powered externally (there are testers from other vendors, I am focusing on Ruideng here). I have recently bought a TC66C but this is a very complicated unit to get your head around. The UM25/34 are child play in comparison. One of these days I'll make a video about it, once I understand the TC66 beast myself. Anyway, for the other testers: On the UM34C: It has a Micro-USB and a USB-C socket. These are alternative inputs, simply wired in parallel with the big USB-A plug. On the UM25C, it has these parallel inputs (same as the UM34C) and an additional USB-C output which is in parallel with the big USB-A socket. These additional micro/USB-C sockets are just there for your convenience so you don't need extra adapters to USB-A. I highly recommend never to plug these testers into two inputs or two outputs simultaneously , as this can cause very tricky problems and easily destroying something. I made a Video about the dangers ruclips.net/video/_JzyoVFNcLE/видео.html (USB-Tester Surprises)
@@TheHWcave wow thanks for the detailed answer! I am really looking forward to your video about the new usb tester. Crazy to for me to imagine after is saw this video, that such a seemingly simple decide could make you stumble.
Excellent video! Thank you very much for explaining in great detail. I have a question, which meter do you recommend me to buy to measure the capacity of the batteries in the power banks and that also serves to measure the resistance in the usb cables.
Thanks Piero, much appreciated. I guess you are not looking for professional kit that will cost hundreds of dollars but like what a hobbyist (like myself) can afford or cobble together. With that in mind, last April I made a video dedicated to measuring USB cable resistance (ruclips.net/video/9IG9wSS3F9w/видео.html ) . Because of the trouble finding breakout connectors to probe USB connectors with normal multimeters, I prefer using USB testers like the UM34 or UM25 to test USB cables. Follow the instructions in my video and not the method built-in to the USB testers itself which is flawed (see my review of the UM34 for more on that). For capacity measurements I use 3 methods depending on how accurate I want the result. The easiest is using USB testers. If you use at least 1 Amp for charge / discharge and turn the screen off to minimize the error caused by the hidden power consumption of the tester, the results will be correct within 1%. I should say that battery capacitance varies anyway with lots of factors (temperature and so on) so 1% is generally good enough, certainly for comparing different power banks. Another way to measure capacity that works with any battery is an electronic load. There is a good one with 60W capacity which is very affordable and even has 4-wire measurement capability. I made a video about it. You find it on my channel. The electronic load and the usb tester generally just give you one number: total capacity in mAh , or energy in mWh which is a much better measure. If I want to record super accuracy or see the actual discharge or charge curve over time, I use my PowerMon (Raspberry -Pi based) and there are a couple of videos on building that instrument on my channel. Works with any battery (up to 20V) but not that easy to make. With less resolution and far less capabilities and limited to USB, you could use a UM34C or UM25C and record the discharge/charge curve via BlueTooth but you would need to keep your Phone/Tablet close by and the app running as well during the time (usually couple of hours!) which is rather inconvenient.
Interesting, I hadn't thought the power consumption of the tester could be such a significant issue... they should allow for either external power or add a shunt to measure internal consumption as well. It doesn't seem too difficult to add a pair of pins for external power, after all.
In principle you are right, but adding external power can cause a lot of issues when using it inappropriately. Don't forget most of these testers are meant for people who do not know all that much about electronics. For example a dodgy charger may work fine for charging a phone through a USB tester even though the charger may actually have a high (100V AC voltage capacitively coupled on the output ( a very common problem). If you now power the USB tester separately from another USB source with a different ground potential, you can cause all kinds of trouble
More comprehensive testers have a separate input power connection (usually MicroUSB).
But the burden current doesn't really matter, since you are usually just measuring the load not the whole system. What I mean is that (say) a Samsung phone pulls 1.9A if it sees a VCC of over 5V, and the USB tester's load and voltage drop is completely irrelevant to those measurements.
I really appreciate this.
Big thanks!
I think EE101 back in college would have been much easier if you'd been the instructor or TA. Subscribed! 💡👍
Is it easy to dump the firmware from the STMicro Chip / did they maybe forget to enable the read protection?
Very comprehensive comparison, Danke!
No idea, but I suppose something like that must have happened. The programming pins seem to be there, but I have not tried using them.
Very good. TNX.
Thank you.
You've done a great job of testing these doo-dads but I'm still wondering which to buy. I see so many versions and quite frankly, I feel like a deer in the headlights, lol.
I can probably live without bluetooth (although I'm not opposed to it) and don't mind spending a few dollars more for something actually useful.
Thanks for your analysis, big thumbs-up!
It depends on what you want to use the tester for and your demands in terms of range, accuracy, resolution (and value for money)
The UM34 has 4-24V at 10mV resolution, 0..4A at 1mA resolution
The UM25 has 4-24V at 1mV resolution and 0..5A at 0.1mA resolution
Both are predominantly for USB-A connectors but can do basic USB-C as well (they have built-in USB-C in and out sockets). Both of these are powered from the USB interface, which is why they can't measure down to zero volts and there is always the problem of their own power consumption as an error when measuring capacity of batteries.
The TC66 (I published a review 2 weeks ago) is a dedicated USB-C tester. You can use it for normal USB with adapters. It does 0..30V at 0.1mV resolution and 0..5A at 0.01mA resolution. It measures from zero when powered separately (through a micro-USB port) and therefore does not load the USB-C bus with its own power consumption.
@@TheHWcave Thx, I'll check out your TC66 review.
When does USB 2.0 vs USB 3.0 matter for a USB tester? Is it only the detection and display of the charging protocol or is there something else that it affects?
It does not matter if all you are interested in is charging but USB 3.0 has more data lines so if you plug a USB2.0 tester into a USB3.0 socket and a USB3.0 cable on the other side, the connection (data speed) will only be USB2.0
Schöner test, ich habe mir die beiden Modelle CT-3 und C3 von AVHzY gekauft, also über 150 Euro ausgegeben aber sicher bin ich mir nicht ob das alles so stimmt als Laie mit der Genauigkeit :) Was ich als Laie nicht verstehen kann ist folgendes: Benutze ich den reinen USB-C Tester "C3" bekomme ich andere Werte bei der Ladestrommessung eines smartphone als wenn ich den USB-A tester mit USB-C Eingang und Ausgang benutze. Das heißt USB Netzteil -> Kabel -> USB Tester -> Kabel -> Smartphone.
There are many things that could influence the current. It is possible that the USB-A wiring in the tester does not support the more advanced charging protocol negotiations., therefore the smartphone and charger settle on a lower voltage/current for charging. Also the cable quality (wire thickness and copper compared to copper-coated aluminium) can cause a difference
@@TheHWcave ah ok, i guess its your first assumption because i plugged a 2A electrical load into both models and they showed identical data. I guess it is something with the protocols then. Maybe the USB-A Version dont support all protocols despite it has an USB-C "in" port. Originally i had the CT-3 and a cheap USB-C tester, both gave different results, thats why i bought the C3 as well. My Ct-3 has a load modul, so its really conveniant for meassuring the capacity of powerbanks.
Watch this before you buy your usb tester. or skip to 44:59 if you trust poster's work.
You described an issue where you werent able to keep your multimeter measurements and the bluetooth readings of the um25c synchronized, did you think about taking the last reported reading of the um25c at the same time you're taking the reading from the multimeter?
Maybe I should have spent more time in explaining. I did not see a way synchronising the recordings between multi-meter and um25c that did not rely on assuming that the um25c was performing well and accurately already, which is really what I wanted to find out.
Recording the spreadsheet from the UM25C is easy, the tricky question is which of the many rows in the spreadsheet produced by the UM25c is the one that corresponds closest to the one moment the multi-meter reading was taken? I thought of adding a column that calculated the delta between two successive um25c readings from one row to the next thus hopefully indicating when a step boundaries occured. But that would depend on the um25c accuracy which we still have to verify. And even if I can identify the step boundary in the um25c data, which of the readings should I take? The last of a step or maybe better the 2nd last as the UM25c may give a reading just in between two steps or take the third last? It all becomes messy and loaded with assumptions.
I’ve seen a couple open source python libs to pull the Bluetooth data. Would that have solved it? Then you’d have a time stamp with the value. OTOH I think I saw the BT resolution is to the second so maybe not small enough?
U4 is probably an ADC from Microchip. MCP3421
hello! is there a way to extract data taken by the device via a cable connection?
Not to my knowledge. I am using the TC66c for that which does that and is extremely accurate. I made a couple of videos on it.
Please more battery content
Oh my, oh my, how terribly horrible! My UT25 arrived today, I guess I have to throw it out of the window, shoot my dog and hang myself! If only I had found your video earlier!
However, I can confirm the rushed soldering of the connectors. One of the side USB-C connectors on my UT25 is not flush with the PCB. Also the screen is misaligned. Not a big deal, I can easily correct both of these. With affordable Chinese products such as the UT25, I am used to the "finish-it-yourself" kind of deal. I will try and ask the seller for a partial refund though.
Well done on all the exhausting measurements.
Why don't you power the meter separately to get rid of it's own consumption ruining the measurement precision?
Not sure if I understand your question. All USB testers work that way (with 1 or 2 very expensive exceptions) and can't be powered separately. My point in the video is that if you use a USB tester you should be aware of their consumption and take it into account. If you want to avoid the consumption, use a normal multi-meter. Of course, the convenience of the USB tester is that it cheap, plugs right in without messy test cables and usually has extras like count capacity (mAh) and energy (mWh) flows. In most everyday cases you probably only want to see roughly what's going on and the 20 mA or so extra consumption does not matter.
@@TheHWcave I am afraid you missed the microUSB port on these testers, which is there exactly for the purpose of separate power
@@tomas_klouda Not really. On these testers, all IN sockets are all connected to each other in parallel internally and just alternatives for your convenience so you can use either for input. Same is true with the OUT sockets, in that these are connected in parallel to each other. If you feed 5V in on the micro-USB IN and 5V on the main type A IN, the current will simply be split between the two. It is not possible to have the internal consumption be handled by say the micro-USB IN and the load current by the USB-A. If you don't believe me, use a multi meter to check connectivity between the IN sockets but for your safety please do not try to feed two IN sockets from different power supplies, because if you do you will inevitably end up reverse feeding the weaker power supply and the chances that it will blow up are high.
@@TheHWcave I see your reasoning, but I still have my doubts. Unfortunately my first USB tester is right now in the mail, so I can't verify. I just spend last few days searching for which tester to order and I went through plethora of reviews, manuals and user discussions.
The microUSB port could be used as an input for cable testing, but it is very often marked as USB HID, not USB IN and is primarily used for connecting to PC for updating FW and recording measurements using PC SW.
Consider the scenario, where you use some of these meters to test QC 2/3 charging of your power bank and you want to use your PC application to monitor/record the measurement. So you would first connect your PC using that microUSB, then powerbank using USB-A or C IN (which are connected for sure) and then some artificial load or another device, that can be charged using QC protocol. Some of these even don't need the load, they can trigger QC 20 V on their own...
In case your statement was true, then switching your power bank to QC at 20 V will inevitably fry your PC USB port if your lucky. If not, than probably USB controller or your PC motherboard will kiss you goodbye.
I know, we are talking about cheap stuff, but I still doubt, that these are designed so poorly, that it will fry your PC while measuring anything above 5V...
Maybe we are talking different models of USB testers here? The UM25/UM25C, UM34 / UM34C used in the video will not send any measurement data over USB at all. The C versions will send data over BlueTooth and that is it. Also I just tested your scenario with the UM25C, charging a load from a QC-capable powerbank but substituting a multi-meter for the "PC" and as expected, when the load caused the powerbank to switch from 5 to 9V , the micro-usb also went from 5V to 9V. These UMxx testers have multiple inputs and outputs but you are expected to use only one of each at any time, never two!
Can this unit detect huawei FCP and SCP?
No, these models don't have ANY 'fast charge' detection, they only measure voltages on Data lines.
You need one of the other Ruideng models to let limited detection of protocols, but there are far better more modern testers that have better protocol detection. Those kinds of testers tend to be more expensive, of course.
überraschend test
Hi thanks for great work. My previous comment has been removed due to external link. My problem is with UM34. Recently I got it. Normally my li-ion charger (vc2s) is able to charge with 2A. However when I use it with UM34, its charging current (seen on the screen of vc2s) hardly exceed 1.7A. So my UM34 behaves like a kind of resistive load and decreases the maximum current allowed, i think. The seller will re-send me. But i suspect the issue is due to USB3.0 support of UM34, because usb3.0 requires 9 pins instead of 4. More pins result in small contact area per pin. But I am not sure, because the bottleneck should be the microusb pins. Do you have any idea?
Thanks
(I requested UM24 from the seller but he didn't accept sadly)
Sorry for the late reply, I did run some tests on my UM34. First of all it does implement all 8+shield signals of USB3, so any charging protocol between battery and charger that worked before should still work. The internal shunt resistor is just 0.01 Ohm so that will drop 20mV at 2A. But as you mentioned there is considerable contact resistance in USB connectors and the cable has additional resistance as well. I measured contact resistance to be in the order of 0.1 to 0.2 ohm on a single contact depending how you jiggle them... so now we are talking maybe 0.4V drop at 2A because of the additional contacts when inserting the UM34. You use the same cable for both but it will have some resistance and therefore drop. The point of all this is that the total load as seen by the charger has now at least 0.2 ohm more resistance, so to still deliver 2A at the battery the charger now has to raise the voltage by 0.4V and I suspect that it can't. One thing to try is to use a shorter/better cable. The reduced resistance in the cable may be enough to compensate for the increase by adding the UM34 so the charge current is back to 2A. A beefier charger won't help because its the max voltage that's the limit in this case.
@@TheHWcave thanks for the very helpful response. I have tried a 6A capable cable to ensure that it is not cable-dependent. But still same result. Can you kindly able to assess the UM25 also, if it won't be too hard for you? I may switch to that later.
However, I think internal resistance of these testers is another brand-dependent parameter. I saw another usb tester which is advertised to have as low as 28 mOhm internal resistance. I couldn't find it now, but maybe that tester would be better for me. As you measure, ~0.2 Ohm is considerably high. Thanks again:)
Ok I did some more tests. Using a restive load on the end of a USB cable with my bench power supply set to constant 5.00V exactly feeding a USB socket. Directly plugging the USB cable with the resistor at the end into the USB socket, the power supply (PS) shows 2.279A, i.e. the total setup (contacts + cable + load resistance) acts like a resistor of 2.194 Ohm. Adding the UM34 drops the current on the PS 2.216A meaning the resistance increased to 2.256 Ohm (+2.8%). Using the genuine UM25 instead, drops the current on the PS to 2.257A meaning the overall resistance is only 2.215 Ohm (+1.0%). For comparison, the clone "UM25" drops the current on the PS to 2.227A meaning a resistance of 2.245 Ohm (+2.3%). Conclusion. The UM34 is indeed the worst of the bunch adding a significant larger resistance (2.8%) compared to the UM25 (1.0%). Even the UM25 clone is better than the UM34 but much worse than the real UM25. This test is certainly interesting and if I ever review more USB testers checking the overall resistance will be included. Not sure what causes the higher resistance in the UM34. Could be contacts and/or thinner PCB traces
@@TheHWcave thanks again, these findings explains it.
GREAT video, tnx 4 the upload !
73 N8AUM
Is there ios app???
I don't have an IOS device myself but as far as I know there is an IOS app called "UM_Meter" for these USB testers in the Apple Iphone app store.
So which one of the best
It depends on what is important to you. UM25C is more accurate and has more digits and goes up to 5A max but is more expensive. The UM34C is less accurate, has less digits and goes to 4A max. The clone is a cheap copy of the UM25C but with questionable built quality. That said, mine is still going strong and I am using the clone more frequent than the other 2 because the clone is just lying loose in a drawer, easy to access while the genuine ones are snug in their nice metal storage boxes... too much work to get them out unless I really need accuracy.
Deutsch-English
So, smart ass... your point is?