IotaWatt 4.0

Tags: #<Tag:0x00007f1bdf710938>

(George (aka Costas the coder)) #153

@glyn.hudson what prevents the new CT’s being suitable for the emonPi and emonTx?

(flywire) #154

More congratulations to @overeasy and @glyn.hudson for development, testing, certification and bringing IotaWatt to the community. Thanks and well done!

(Glyn Hudson) #155

Unlike the IotaWatt the calibration factor on the emonPi / emonTx is set in the firmware. It would be possible to use different CT’s but the calibration / phase shift would have to be updated in the firmware. This would not be an issue for technical users to re-compile then upload the FW but not all users would be able (or want) to do this.

(Glyn Hudson) #156

Cheers, thanks for your support :blush:

@overeasy did all the hard work, full credit to him it’s a fantastic unit.

(George (aka Costas the coder)) #157

I will start a separate thread regarding CT’s to try and get a better understanding of the calibration and phase shift.

(Mike Dilger) #158


Long time lurker here, but your post is timely to what I am working on.

I am about to start testing multiple CT options (both split and solid core) from YHDC for the monitor that I am developing. I will be happy to contribute my test results in due course.


(George (aka Costas the coder)) #159

@MikeD can I direct you to the new “CT” thread at Implications of using different CT’s with Open Energy Monitor Hardware

(Gwilym Noble) #160

A post was merged into an existing topic: IotaWatt three phase development

( Earl H) #161

Hi Bob, congratulations on the release. Is it possible to order through the Open Energy Monitor store and have it shipped directly from your shop to New York (to save shipping cost and get it faster)?

(Inactive) #162

Hi Earl, thanks for the kind words. I’m sorry that I’m not equipped to fulfill US orders. I’m trying to remain an OEM (original equipment manufacturer) and let OEM (Open Energy Monitor) take the lead on retail. They do some final assembly, add a component, label, load production firmware and test. They have a dedicated person who will do a professional job. My 160 sq ft office/lab on the other hand… At least you don’t have to pay VAT.

(Paul Reed) #163

3 posts were merged into an existing topic: Homebrew IoTaWatt issues

Homebrew IoTaWatt
Homebrew IoTaWatt
(jan) #168

@overeasy: Do you have any idea of the memory consumption on the SD card? (i guess its channel related) The specs page mentions 8gig sd card minimum, but you picture in this tread (very top) shows a 4 gig card.
What happens when the sd card is full?

(Inactive) #169

Jan, the datalog is still in a bit of a flux. You are safe with either a 4GB or 8GB card, but I would recommend going with 8gb for the long haul. This type of memory has wear management built in, and over a number of years some of the blocks can be at their statistical end-of-life. There are enhancements to the datalog system in development that will support up to ten-years of historical data at a lower resolution (1 minute), so spending the extra couple of $ for 8Gb is a good investment.

(Glyn Hudson) #170

I’m currently working on a setup guide for the IoTaWatt to go on our User Guide Site. Dones anyone who has received an IoTaWatt so far have a tidy installation photo to hand that you would be happy for me to use? Our dev setup IoTaWatt install is not particularity tidy! Thanks.

(Elias - RExometer) #171

Sorry I missed that post. Thanks for working on that. For me it would be ideal to have the opportunity to log these values at the same interval as power.

(Inactive) #172

You caught me just as I was starting work on long term archival storage for the datalog. What I am currently contemplating is to have the existing datalog continue to be a 5 second interval resource for the most recent year, and to have a history log that keeps the same information, but at 1 minute intervals for potentially up to 16 years. The current log record has adequate room to save the power factor and frequency. All of the graph current graph functions can be serviced from a 1 minute interval log unless the zoom in feature is used. That will show the granularity in the graph if the request is for data more than 1 year old.

(Inactive) #173

Sorry to be late answering this. Just saw it for the first time.

To connect a 9V AC VT to one of the power input jacks 1-14, you would simply wire the AC adapter to the tip and ring of a 3.5mm stereo jack, inserting a 288 ohm 1/2 watt resistor in series on one of the connections. I intend to make some adapters that accept the 5.5mm barrel plug on an AC adapter and have a 3.5mm jack, but haven’t gotten around to it yet.

On the software side, just configure the input as a VT and select the model from the table or use generic as in the wiki instructions. You probably should do the calibration procedure as well.

IoTaWatt does not automatically detect the matching voltage reference. That’s hard to do and the situation can be ambiguous if the phase separation is not 120degrees and/or the power factor of the load is less than .5

There is a capability to measure the apparent phase difference between a VT and a CT, so that could be used to make the job of manually assigning VT easier.

It sounds like what you have is independent power systems with a common neutral. Since you have to manually specify the reference voltage channel for each CT, you should be able to have any number of these. If I were to develop some automatic VT assignment scheme, you would probably need to override it.

Different frequencies should not be a problem as long as the CT/VT matchup is correct. I am assuming the frequencies are in the 50-60Hz ballpark.

(dBC) #174

Are they pure sinewave inverters, or modified sinewave?

(Minos Eigenheer) #175

We have pure sine wave inverters.
It sounds like everything should work if I use one VT for each phase.

(Frogmore42) #176

Is the coupon code no longer possible. This morning I was able to find a box to enter the code on my phone, but later when I went to complete the order on my computer there is no box to enter the code and when I went back to the phone it was there but then disappeared when I refreshed the screen (since it now had two in the cart).

Looks like a great product and I am interested in getting one.