IotaWatt First Impressions

Hardware IoTaWatt
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So, I was able to get my order completed (credit card company called my wife to make sure someone hadn’t used my card without my knowledge, luckily she said that sounded like something I would buy, though they said it was from Israel :slight_smile: ) and then the Post Office didn’t actually deliver it so I had to go pick it up the next day.

It survived the trip well and everything looked okay. If first plugged it into my PC to see if there was anything interesting on the serial output. It didn’t take long to figure out that it was using 115K baud (but it would have been nice to note that in the getting started, as a footnote).

The micro USB connector is recessed quite a bit, so it makes the USB part quite easy to disrupt. I don’t believe there is an easy solution to that. Power wise it seems okay. It has been running for over a day (no longer connected directly to my PC).

Plugging in the power brick showed there was voltage, but it was configured for 240V. I could not get it change and I was getting some weird behavior and it looked like it was going out to lunch. I spent a bit of time trying to figure out what was going wrong. I even tried IE and that was giving script errors. I turned on debugging and saw that events were getting fired at a fast rate. So, i figured development must have been done on Chrome and that I should try that. After installing it, I was able to complete the setup of the VT and calibrate it to my Fluke 87V.

I then moved it downstairs to the breaker box and hooked up some of the CTs. Those cables are way too short for my setup. (I have a decent size breaker box, actually smaller than many, and the cables on the 20A ones won’t make it from the top breakers to the box I have below the main one. Luckily I have a bunch of other CTs that have longer cables and that is what I will use, once I figure out the calibration for them.

The choice of 3.5mm plugs seems nice (at first) but it seems it is hard to get high quality ones and most of the cables use really hard to work with enamel wire. Luckily I was able to find some plugs with screw terminals that look like they will work okay.

The next issue I ran into is how to correctly configure a 240V load. I have quite a few of these, well pump, septic tank pump, water heater. Since they are 240V only, they only need a single CT. But it doesn’t seem possible to get the correct energy using only a single CT.

I filed issues on GitHub for the web browser and CT configuration.

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Thanks for the review. Hope you can provide some feedback on accuracy when everything settles down.

Responses to the Github issues are posted there. Graphing energy (Kwh) for outputs is done but not yet merged and released, power (Watts) does work ok now.

Looking into the potential IE javascript issue. You noted both Edge and IE, but probably the same JS engine. Browser compatibility is a jungle.

As you said, micro USB is limited by the 3mm case thickness. It’s a tight fit. The nodeMCU is right up against the inside of the case. It does seem to work OK with connectors from CUI and other major suppliers. I recommend using the wall mount to place it vertical with the USB at the top, so gravity works in your favor, especially if there is any vibration.