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Digital panel meter - Voltmeter / Ammeter - made in China.

CMS 34569 90

TL;DR

  • A cheap Chinese panel meter combines a voltmeter and ammeter in one neat housing.
  • It measures 0-100V DC, and two tiny trimmers let you calibrate it after unpacking.
  • The seller quotes 1-10A, but this copy already starts at 0.01A and showed about 20mA error at 200mA-300mA.
  • It costs about PLN 6.
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  • #61 19361005
    M.R-V4
    Level 24  
    An alternative to the measure / indicator described above can be the D85-3051AG model. It is bigger (and more expensive), but in my opinion it is more readable. Of course, it also has the ability to calibrate, but "out of the box" it shows what a universal meter, although it is no ;)

    The price is about PLN 30 on the Chinese portal. This is how it looks in the pictures:

    Digital panel meter - Voltmeter / Ammeter - made in China.
    Digital panel meter - Voltmeter / Ammeter - made in China.
    Digital panel meter - Voltmeter / Ammeter - made in China.
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  • #62 19361170
    damian1115
    Level 37  
    When this topic has already started again, and there are more and more news on the Chinese market, I would like to ask my dear colleagues what do you think about this gem.
    Digital panel meter - Voltmeter / Ammeter - made in China.
    https://pl.aliexpress.com/item/4000111098529....scm=1007.13338.192130.0&scm_id=317.133b.1933l =&scm_id=317.133b6.1933l =&scm_id=317.133b.1933l=21 -4a92-b013-47f3fbe4e38d & _t = gps-id: pcDetailBottomMoreOtherSeller, scm-url: 1007.13338.192130.0, pvid: fbca6c31-6583-4a92-b013-47f3fbe4e38d, tpp_buckets% 2361968% 2361933% 2361968% 2361933% 2361968% 2361933% 2361968% 2361933% % 23192 130% 230_3338% 233142% 239 890% 234_668% 232 846% 238 115% 232000_668% 232 717% 237 565% 23773_668% 231000022185% 231000066059% 230_668% 233,422% 2315,392% 23,326
  • #63 19361318
    CMS
    VIP Meritorious for electroda.pl  
    I have it, it works fine, but the Chinese descriptions on the front are annoying.
  • #64 19361472
    M.R-V4
    Level 24  
    I have a similar one, the indications are also correct after a small calibration.

    Digital panel meter - Voltmeter / Ammeter - made in China.
    Digital panel meter - Voltmeter / Ammeter - made in China.
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  • #65 19361480
    gimak
    Level 41  
    I would be more interested in indicating not the power, but the energy that has been passed through this meter in the time period I am interested in, e.g. how much energy I got from PV panels on a given day, week or month.
  • #66 19361502
    damian1115
    Level 37  
    M.R-V4 wrote:
    I have a similar one, the indications are also correct after a small calibration.

    Your one is a bit different where you bought it.
  • #68 19383602
    ElectroTom
    Level 25  
    To the post by Damian. For me, the parallax error caused by the lcd display is irritating.
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  • #69 19384205
    Szyszkownik Kilkujadek
    Level 37  
    ElectroTom wrote:
    To the post by Damian. For me, the parallax error caused by the lcd display is irritating.

    Can you tell by what miracle on a digital display you can get a parallax error? :-)
  • #70 19388749
    lukiiiii
    Level 29  
    Maybe it's a 3D display?
  • #71 19388937
    ElectroTom
    Level 25  
    That's how it reminded me. Parallax - the effect of incompatibility of different images of the same object observed from different directions.
  • #72 19934710
    mumotg
    Level 6  
    Hello, I bought 2 meters like in 1 post and both show 125A at once. It turned out that the Chinese did not solder the shunts, the question is what shunt should be soldered there?
  • #73 19935083
    gimak
    Level 41  
    Maybe not so much the Chinese forgot, as you forgot to enter the current range. In this case, the shunt will probably not be soldered, but connected with screws. Shunt suitable for the measured current range with a 75mV output (connected to the module).
  • #74 19935092
    mumotg
    Level 6  
    Hello, what shunt should be soldered to 10A?

    Added after 7 [minutes]:

    Can it be like that? Digital panel meter - Voltmeter / Ammeter - made in China.
  • #75 19937098
    gimak
    Level 41  
    Assuming that there should be a voltage drop of 75mV on the shunt at 10A, this resistor is a bit too big and probably with its use the meter will show 10A with the actual flow of 7.5A.
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  • #76 19938118
    mumotg
    Level 6  
    What is there to solder with
    to be OK?
  • #77 19938184
    Szyszkownik Kilkujadek
    Level 37  
    A resistor with a voltage drop of 10A at 75mV. Just.

    Added after 2 [minutes]:

    Of course, you also have to take into account the power that will dissipate on this resistor during the flow of the maximum current.
  • #78 19938230
    gimak
    Level 41  
    I will not answer unequivocally, because I do not know what the module you have looks like and whether there is a place for soldering the shunt.
    I have two types of such modules, both with 10A range. In one there is a piece of wire soldered as a shunt, and in the other one there is no such soldered wire and its role is probably played by the appropriate thickness of the tin on the path.
    Judging by the shunts for such modules that I saw on the Allegro, for example 50A -75mV, i.e. with a current of 50A, there is a voltage drop of 75mV on it and this voltage drop is measured by the meter and the reader shows it as 50A - I think, because no I played these blocks with electronic meters.
    So with a 10A shunt, by analogy, the resistance of this shunt should be 0.0075? (7.5 m? ;) so that at a current of 10A there would be a drop of 75mV on it.
    I admit that I cannot imagine such a precise soldering of such a shunt.
  • #79 19938992
    mumotg
    Level 6  
    Thanks for the answers, that's my measure Digital panel meter - Voltmeter / Ammeter - made in China. I trimmed the shunt with it and soldered it on Monday, I will see how the measurements will come out Digital panel meter - Voltmeter / Ammeter - made in China.
  • #80 20408347
    kristof_61
    Level 11  
    Hello.
    I have an ammeter.
    Digital panel meter - Voltmeter / Ammeter - made in China. Digital panel meter - Voltmeter / Ammeter - made in China.
    On the 16-pin system, it says FMD B1dKBMH, I haven't drawn the schematic yet and the problem is that it slightly underestimates the measurement result. With a PR of 5K at max, it still shows too little. For now, I have only made one measurement and with a load of 160mA it shows 130mA. Can the PR be exchanged for another value?
  • #81 21358659
    Daro1003
    Level 34  
    Hello archived topic but I have a problem with these meters.

    I have bought several of these meters and in each the same problem namely when only the power supply is connected the module shows 52A as in the picture.

    Digital voltage and current meter with display showing incorrect reading of 52A with thick wires disconnected. View of meter modules with connected power wires, showing incorrect current reading of 52A. Three electronic meters with colorful wires on a concrete surface. .

    Apart from the phone didn't catch the digits but the display shows voltage 00.0 by current 52A thick black and red wires not connected for now if I connect the yellow one it shows supply voltage but still current 52A
  • #82 21359777
    Wawrzyniec
    Level 38  
    Daro1003 wrote:
    Apart from the phone did not catch the digits
    .
    Not only that. It didn't catch the shunt either. It's probably not there, but show what board there is without covering it up with plugs. If there is no shunt then plug it in and it will show the current correctly.
  • #83 21359798
    Daro1003
    Level 34  
    Yes exactly, unfortunately there is no shunt in each piece and nothing in the packaging either. I bought the voltmeter about a year ago and it was waiting to be used and now it's gone and I have no idea why it was sent and now it's useless unless you can buy such shunts somewhere in the form of a wire for driving.
  • #84 21360115
    gimak
    Level 41  
    You can buy shunts, you just need to specify the current and the voltage drop across it - e.g. a 50A 75mV shunt.
  • #85 21367162
    Daro1003
    Level 34  
    Yes, I need up to 50A, not more for sure, and even up to 20A, where can I buy such a thing ? And in what form for soldering to a PCB ?
  • #87 21367310
    Daro1003
    Level 34  
    And this is no longer a profitable topic for 10zł you can buy 1 piece of working on allegro. I thought I could buy the wire missing from mine somewhere.
  • #88 21367368
    modziul
    Level 33  
    >>21367310 Item 7 is this wire. I don't see a shunt like this on Allegro under a dozen pounds with delivery and from China. I just got a refund from Allegro because the Chinese sellers there put in whatever they can find and can't deliver.
  • #89 21367419
    Daro1003
    Level 34  
    Item 7 is a gauge I think with this soldered wire. The whole 8 zł. On allegro at 10-11zl only here again shipping or on samrta and we have multi-piece.

    Digital meter with LED display and wires, priced at 8.09 zł. .
  • #90 21367535
    modziul
    Level 33  
    >>21367419 Well, here's a tidbit for the IT industry because with me it's correct on my computer and phone (different access)
    Screenshot of a 50A shunt offer on Aliexpress.

    Screenshot of the AliExpress app showing an offer for an ampere-voltmeter.
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Topic summary

✨ The discussion centers on inexpensive Chinese digital panel meters combining voltmeter and ammeter functions in a single panel, typically costing around PLN 6 to 30. These meters measure DC voltage up to 100V and current in the 1-10A range, with some models supporting automatic range switching. Users report variable accuracy, especially in current measurement at low and high ranges, and non-linear voltage readings. Common issues include LED segment burnout, unstable readings at low currents, and significant measurement errors when charging batteries with thyristor-based rectifiers due to waveform distortions. The ammeter input wires are often too thin, causing voltage drops and overheating; upgrading to thicker wires or direct soldering to the PCB is recommended. Some meters lack pre-soldered current shunts, requiring users to install appropriate shunts with a 75mV voltage drop at rated current (e.g., 10A or 50A). Calibration using potentiometers can improve accuracy. Negative voltage measurement is generally unsupported, but users seek simple circuits to enable this. The meters are sensitive to grounding schemes; connecting measurement and power supply grounds improperly can damage the device. Adding smoothing capacitors across the ammeter input can stabilize readings but may interfere with thyristor regulator thresholds. Variability between units is high due to inconsistent manufacturing and undocumented design changes. Alternative models like the D85-3051AG offer larger displays and better readability at higher prices. Users share photos and schematics to aid troubleshooting. Overall, these Chinese meters are considered suitable for amateur or workshop use where cost is critical, but not for precise or professional measurements without modification and calibration.
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FAQ

TL;DR: After a 2-minute trim the Chinese 0-100 V / 0-10 A panel meter reaches ±2 % accuracy [Elektroda, koala106, post #17118384]; “worth the money” [Elektroda, h3c4, post #17117098] Calibrate two onboard trimmers, mind a 75 mV shunt, avoid reverse polarity. Why it matters: A €2 gadget can become a trustworthy lab readout when you know its limits.

Quick Facts

• Measurement range: 0–100 V DC & 0–10 A DC [Elektroda, CMS, post #17116791] • Power requirement: 4–30 V, ≥100 mA [Elektroda, CMS, post #17116791] • Typical post-cal accuracy: ±2 % of reading [Elektroda, koala106, post #17118384] • Cost at purchase: PLN 6 (≈ US $1.70) [Elektroda, CMS, #17116791; mariomario, #17117318] • LED lifespan: some fail after 6 months, others run 3 years 24/7 [Elektroda, h3c4, #17117098; jousto, #17117168]

What are the official voltage and current limits of the meter?

The module reads 0–100 V DC and 0.01–10 A DC. Seller notes usable accuracy starts above 1 A, yet the display activates at 0.01 A [Elektroda, CMS, post #17116791]

How do I wire the three- or five-lead version correctly?

  1. Connect thin red to +V supply (4–30 V).
  2. Connect thin black to supply ground; leave floating if supply equals measured source.
  3. Route load current through the thick red (+) and thick black (−) leads.
  4. For separate voltage sensing, attach thin yellow to the point you want measured [Elektroda, CMS, post #17116791]

How do I calibrate the displays?

  1. Power the module and connect a precise DMM in parallel.
  2. Use a small insulated screwdriver to turn the VOLT trimmer until both meters match.
  3. Repeat for the AMP trimmer while passing 5 A through the shunt. The entire process takes under three minutes [Elektroda, CMS, post #17116791]

What wire or shunt size is safe for 8 A continuous?

Replace the stock 0.2 mm² leads with 1.5 mm² copper; originals overheat and melt at 7 A [Elektroda, mariomario, #17119795; koala106, #17120194]. Keep lead length short to limit voltage drop to <50 mV at 8 A.

My board arrived without a shunt and shows 52 A at idle—what value do I need?

Solder or bolt in a 0.0075 Ω (75 mV @ 10 A) resistor for a 10 A range. For 20 A use 0.00375 Ω, for 50 A use an external 75 mV/50 A block. Without the shunt the op-amp saturates at ~52 A reading [Elektroda, mumotg, #19938992; Szyszkownik Kilkujadek, #19938184].

What happens if I reverse the current leads?

The meter shorts its internal 5 V regulator and can fail instantly; at minimum it shows 0 A [Elektroda, CMS, #17116791; Anonymous, #17119702]. Always observe polarity or add a series Schottky diode as cheap insurance.

Can the meter display accumulated energy (Wh)?

Not the basic 3-digit unit. Choose a KWS-DC200 or similar; it integrates voltage and current to show amp-hours and watt-hours, resettable via front button [Elektroda, M.R-V4, post #19361472]
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