New iTead Sonoff POW R3 - 25A Relay

So every once in a while we seem to find some strange home automation product designs.  When I saw the name of POW R3 come across the FCC docs as 2APN5-POWR3 I was excited to see the new design.  If you aren't familiar with the previous model, POW R2 it was basically a large box at over 4 inches (114mm) long with power monitoring and a relay.  It definitely was a tank but its hard to park that tank in the garage!  

UPDATE: The page is live on iTead for the POW R3 already!

(POW R2 - source

When iTead redesigned the new Sonoff Dual in the R3 revision, I was really impressed (video link).  ESP32, dual switch inputs, dual power monitoring in small form factor design.  The new redesign of the POW is got bigger!

Pics from the FCC Filing

First thoughts.  ESP8266!  WOOT!  Header pins and things labelled.  YES!  Great job OYO for thinking of the DIY community!  Tasmota or ESPHome is waiting to be installed.  What are these empty headers here?  Call me! 

By looking at the one exterior picture and the 100-240V 25A rating, I'm guessing this is meant for a DIN rail installation and not targeting the in-wall solutions like the Dual R3 is.  Did you see the size of this thing? Beefy! It is a rather odd design compared to things in the past from the jumper wires from the wiring terminals, separate power supply board, current sensing "donut", etc.  I was surprised to see the ESP8266 and not the ESP8285 but they might have needed the additional storage for the onboard power monitoring history in the stock firmware.  The ESP32 might have been the better choice here as it doesn't appear many cost saving measures were taken into consideration and that would have allowed to do that sweet bluetooth pairing.

The last interesting piece was the relay, looking at the datasheet it appears the relay is a normally closed design.  This means even if the device is not powered then electricity will flow through the switch circuit.  This is very different from their devices in the past.  For instance if you take the Sonoff S31 Washer/Dryer project video, you want these devices to be powered at all times usually.  This means the ESP chip needs to be powered and it is sending a signal to the relay to allow electricity to pass as the relay in the smart plug is normally open without a signal present.  While this might not be an issue in most cases, it is still a waste of energy and if the relay fails, it will not pass power anymore. Nice touch to see this choice of a relay. 

I'm looking forward to seeing this on the bench when it is released.  I'll ponder a 25A load test until then....

Source - FCC Docs

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  1. I haven't checked the specs yet, but I'm wondering if my old (no remote) window air conditioner would be a good use case for this device.

  2. Strange that they made 25A 240V single-phase version as as far as I know no 240V single-phase devices uses 25A on their own. Most 240V devices that have higher then 16A rating use three-phases (similar to two-phased in the united states). Most I seen is 16A 240V single-phase device (washer, dryer, wather-pump, heat-pump). I guess they are thinking people want to connect more devices to one unit, like washer and dryer on the same switch.

  3. 25A is for hot water boilers (geyser) for the house water supply. Have used the POW R2 and the current exceeds the limit of the 16A relay. Well done Sonoff as i was waiting for this device, as i have modified the R2 with solid state relays and having the device designed from the ground up to carry the heavy current amazing!!!

    1. But most if not all 16A+ (20A or more) hot water boilers appliances use three-phase in Europe.

    2. I've seen quite a few single phase pictures on the net of installs along with boilers themselves being 1 phase. Makes sense given the 240


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