Emonpi setup issues

Hi, I hope someone can help me.
I’m trying to configure my new emonpi, but, whilst it sort of works, it doesn’t seem right.
It is logging readings, but they are way too low to be correct.
I have the following connection:
DC power supply.
AC power supply.
CT1 on neutral wire between meter and consumer unit.
Ethernet connection.

I have configured the input feeds via web interface, but the power reading is only one tenth of what I might expect (200w instead of 2kw).
I was wondering about the vrms reading. It reads around 38. Should that not be about 240?
Additionally, the push button on the emonpi unit is not very responsive. Most of the time it ignores me when I press it. Should it not easily cycle through the menus?
Any suggestions where I should look / things to try ?

Welcome, and sorry to read you have problems. From what you’ve written, I think the low Vrms is definitely to blame. Have you measured the voltage out of the Ideal ac adapter - you should see about 11.6 V?

As another test, if you fire up your emonPi without the ac adapter plugged in, it should recognise that it’s missing and default to a fixed 240 V, which will give you approximately the correct power.
You must have the ac adpater plugged in and on before or at the same time as you start up your emonPi for it to use the adapter to read the mains voltage.

Normally, it responds to a button push, but if you’re very fast, it might miss it.

1 Like

Hi Robert. Thanks for the welcome and the suggestions.

As you recommend, I did power up the AC and DC supplies simultaneously.

The AC output from the Ideal supply whist not connected to the emonpi is 11.6V.
After repowering the emonpi without the AC, the vrms in the web interface reads 14.7.

I will have a nose inside the unit and see if I can see anything untoward.

It looks very much like something serious is amiss inside, then. It should have recognised the absence of the ac voltage and used a constant 230 V (sorry - I wrote 240 from memory) instead. However, it appears to have recognised the presence of the ac input (which it should not have done - it’s far below the threshold). I don’t quite understand what’s happening, unless you’ve accidentally changed the voltage calibration in emonhub.conf

You can look at emonhub.conf when you log in to the Pi with a web browser. You’re looking for this:

    nodename = emonPi
    firmware = emonPi_RFM69CW_RF12Demo_DiscreteSampling.ino
    hardware = emonpi
        names = power1,power2,power1_plus_power2,Vrms,T1,T2,T3,T4,T5,T6,pulseCount
        datacodes = h, h, h, h, h, h, h, h, h, h, L
        scales = 1,1,1,0.01,0.1,0.1,0.1,0.1,0.1,0.1,1
        units = W,W,W,V,C,C,C,C,C,C,p

The 4th value in “scales = …” is the scale factor for the rms voltage, it should be 0.01 as above.

If that’s correct, then it sounds to me as if an email to the shop is called for.

I have found a fault on the board.
I was tracing the sine wave from the AC input with my scope and it looks like the plating through on the last via before the signal reaches R4 is non-conductive. i.e. the signal is there at the bottom of the hole but not at the top.
I’ll contact the shop as you suggested. Thanks for your help, although I can’t promise I won’t be back with more hard questions :smile:

That’s definitely a replacement board for you. Do let the shop know (and point them at this thread) so that they can keep an eye on the suppliers.

Oh dear :frowning: . Very sorry to hear, top effort fault finding :thumbsup:

We will certainly organise a replacement. Please contact shop support with your order number.

Thanks a lot @Robert.Wall for helping out.

Thanks Glyn. I have emailed shop support and am awaiting a response.

Response given! Replacement will be dispatched later today.

Wow that was quick. Thanks. :smile:

Replacement board arrived today. All connected up and working. yay! :smile:
Thanks guys.