Making a fake Chinese Wattsup 12V power meter less dangerous

You can buy a pukka Wattsup meter from RC Electronics for $60. That’s just too dear for me, I want to be able to apply a few of these in various places, so I go with the cheap fake Ebay version for £5.99 🙂 At the time I didn’t realise it was a cheap fake Wattsup, it was simply billed as Watt Meter

as it arrived

as it arrived

It duly arrived from some joint in Shenzhen and it wasn’t hard to see that quality control left something to be desired. But hey, whaddya expect for £6? I couldn’t source the LCD display and box for £6!

Chinese suppliers don’t actually have to deliver reliability at these low prices because the cost of sending the product back to China for a refund is higher than writing off the goods. Since I’m prepared to fix the odd part I’m happy to take the risk. It didn’t seem to be a good idea to apply a 12V car battery to this sucker as is, without some investigation. Plus having the display centred is a nice touch…

1512_DSCN2785Hmm, nothing to centre the boards. Other than that, looks okay, except for the exposed positive solder joint in the main battery 12V line Insulated from the case by the blue anodising and now’t else. At least the LCD contacts are pushed away from the metal by some foam. The LCD groundplane ends just shy of the edge of the board so it may not short on the box, but it still seems a risky business to risk having the box at +12V potential when the anodising gets scraped through. Most 12V systems assume exposed metalwork is either isolated or connected to the negative terminal. I don’t feel that lucky as to go around with a +12V exposed metal box, so I got some of that pressed card (plastic can easily melt if it gets hot) and put it in inside the box, to at least give me an extra layer. I do see the wisdom of RC electronics using a plastic case, but then an 80% discount speaks a language of its own. How do I know it’s a fake Wattsup? Well, a Google for 12V watt meters showed me the Watts-UP, and the display layout looks very like it. Indeed the Watts-UP V2 manual showed me the design philosophy, what the display actually means, in particular the Data Queue  and how to use it, as well as what the auxiliary power port means, a lot more useful than than the Chinglish sheet that came with it. The UI is designed well enough that I’d have been able to use it without all that, but it’s nice to know.

Wattsup-like display

Wattsup-like display

On testing it gives me reasonable values for current, voltage and power. The front of the Chinglish info sheet claims it’s made in the USA to ISO9001:2000 quality standards on the front page. If you ask ISO they have an article on what this means, and I can save you the trouble of Googling the link to their own content they talked about but failed to add, I think it is safe to say that my Chinese supplier failed to meet the aims of ISO9001:2000

One of the primary objectives of ISO 9001:2000, as clearly described in Clause 1.1 of the standard is “ to specify requirements for a quality management
system where an organization…
needs to demonstrate its ability to consistently provide product that meets customer
and applicable regulatory requirements…”

Fail for the Chinese supplier in failing to provide a piece of gear where you could see the display as delivered and was reasonably safe in the proposed application. And indeed was as described, since overleaf they changed their assertion as to where this piece of kit was made to “Made in china”

I will calibrate against my DVM  but it seems basically a serviceable product at a jolly good saving if you’re prepared to do the extra work to make it safe and test it. I like it – I’ll get some more

7 thoughts on “Making a fake Chinese Wattsup 12V power meter less dangerous

  1. Gwill Jones

    Richard,

    Thanks for this link.

    I think that with your recommendation I will get one. I already buy quite a few electronic devices from China; and like you, I find that they are extremely economic. Also I have found that they don’t quibble about sending a replacement (except for about one month delay) if a parcel doesn’t arrive.

    I get the impression that you are in the UK. I live near Stourport in the West Midlands; where do you live?

    Gwill Jones

    Reply
    1. richard Post author

      I’m from Ipswich in East Anglia. I got three more of these since writing this, and out of the four in total one reads current about a third of the real value, the others are within about 10%. It’s not too bad for the price, I’ll probably toss the bad one but the total cost is still less than that of a real Watts Up. You pays your money and you takes your choice 😉

      Reply
      1. Gwill Jones

        Richard,

        Thanks for your reply.
        I forgot to look back in June, but I have bought the Watt Meter that you described.

        I’ll let you know what I find when I actually use it. At the price, I think that I will be prepared to connect it up to !2 V and trust to luck that it will work.

        My own interests are wide ranging and I tend to be moving from one thing to another, mainly with the soil as my main interest.

        Looking at some of your other documents | am surprised at the lack of communication that appears at the end of your documents.

        A applaud your continued publication on your website when you get so little response.

        I am getting interested in paramagnetism for testing soil and compost, and with the help of some of your documents I can see that I can do some experimentation.
        I have bought Callaghan’s Paramagnetism book (which arrived today) but it doesn’t give me a lot of actual help in getting started with experimentation; your documents seem to be much more useful.

        Do you have any links that might be of further help?

        I will have to remember to look at your website again for your reply, and not leave it for 6 months this time.

        Gwill Jones

        Reply
        1. richard Post author

          Thanks for your kind words. I don’t use FaceTweeter, because attention is the currency of the Internet and life is short 😉 Hence Google is the only way people find anything of mine. It’s OK by me.

          Have you seen the Measuring paramagnetism series? If you want to make that I’m open to tossing the asm file on github if I can find it, but you need to be able to program PICs. It would be easy to do in an Arduino but I didn’t do that.

          Reply
  2. Gwill Jones

    Richard,

    This time I have remembered to look for a reply.

    Yes I have seen all of your series notes on paramagnetism and they have been a great help. I was hoping that you could give me some other links or references that may help me more. There does seem to be a shortage of information about paramagnetism.

    I think that with Patent No: 7,241,630 and your various notes, I shall be able to delve further into experimenting with paramagnetism. I shan’t bother to try to copy the circuits of the patent, but the patent will guide my thoughts.
    I can see that the susceptibility level of paramagnetism is very low and that may give me the most problems. I will try to design different electronic circuits that may help me to get over the problem of low susceptibility. I am 85, but I formerly taught electronics within robotics at University, so it will just tax my brain a little. Quite possibly a mixture of analogue and microcomputer circuits might lead the way.

    I looked at http://www.bartington.com/Literaturepdf
    This link was mentioned in one of your posts. Have you any comments on this link that may be of interest to me. I have looked at many of the sub-links at bartington.com. They do seem to be very forthcoming with information.
    Like you, I cannot afford the expensive equipment, but I am in a position to be able to experiment and hopefully end up with a useful system that I can use in the garden.

    Regards,

    Gwill Jones

    Reply
    1. richard Post author

      The low susceptibility wasn’t too bad – I used the dual opamp Franklin oscillator around 1.5kHz and used interrupts on change (to get frequency-doubling to improve resolution). I just count the interrupts over 4sec with the coil not near the rock to calibrate, and save this count. Then introduce the sample to the coil and repeat for measure. Do the integer maths described here on the two counts and you’re done.

      It’s a reasonably easy project. Probably easier with an Arduino, which has the same sort of interrupt-on-change function I think. The differential nature of the measurement takes out all the long-term stability issues, and measuring signal transitions over 4s gives you enough resolution to pick out small frequency differences.

      Bartington have machines that use the Gouy balance too, but the thought of doing that in the field didn’t appeal.

      Reply

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