Hi all,

I’m looking for a reliable smart plug with current/energy monitoring that meets these requirements:

  • Ideally <1s time resolution (I need fast updates, not just averaged every few seconds.)
  • Wi‑Fi connectivity preferred, with MQTT client support out of the box (similar to how Shelly devices can publish to a local MQTT server when the load current changes. I’d rather not have to poll a device’s HTTP endpoint a few times per second.)
  • Provisioning/config: Bluetooth for setup would be a big bonus (I think the Shelly Plug S Gen3 can do this, too.)
  • Reliability/manufacturer: Needs to be from a well‑supported brand or at least something that’s proven stable and not a “cheap no‑name” option.

I’ve been testing a few devices already. Most average power consumption over longer periods, while e.g. newer Shelly devices come frustratingly close to being exactly what I need.

Does anything on the market provide sub‑second resolution for current measurement? Most consumer plugs I’ve tried either average readings or only publish once every few seconds, which isn’t quite enough for my use case (measuring transient behavior and categorising operating modes of certain appliances).

Has anyone come across a plug that ticks these boxes? Or maybe a hidden configuration with Shelly devices that I’ve missed?

Thanks a lot for any help!

Edit: What I’m actually looking for is a fast response time to significant changes in power consumption (by more than a set amount or a percentage), so a high sample rate within the plug. A constant delay until the message is sent out wouldn’t be a problem at all.

  • tofubl@discuss.tchncs.deOP
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    5 days ago

    Hm, is it possible that “virtually immediately” means different things to us? I have now thoroughly benchmarked a Shelly AZ and am currently investigating a Shelly PlusPlug S (Gen2 I think), and they are both far from where I would like them to be.

    Here’s the result from a 1.5h run, toggling the load every few seconds:

    Shelly AZ Turn-ON delay (standard deviation) Turn-OFF delay (standard deviation)
    HTTP Polling 2.0s (0.8s) 2.3s (0.7s)
    MQTT Subscription 1.9s (0.8s) 2.2s (0.8s)

    The PlusPlugS V2 is even worse.

    The real problem with this, other than delayed and missed events, is the standard deviation. A constant delay would be okay.

      • tofubl@discuss.tchncs.deOP
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        5 days ago

        Ah, I see. I thought EM and PM are just other smart plug models. Sadly, not a viable solution for me- I need it to be a smart plug type of device. I wonder if those have more precise or faster measuring circuitry or if it’s just a different firmware for a different use case.