SONOFF S31 WiFi Smart Plug with Energy Monitoring, 15A Smart Outlet Socket ETL Certified, Work with Alexa & Google Home Assistant, IFTTT Supporting, 2.4 Ghz WiFi Only (2-Pack)

Update: It appears that I have spoken too soon. Out of the 6 total units that I have now, 2 of them will not power on or pair (I am 7 days in the dark with their customer service with this so far) and 3 of them randomly read as Unavailable. Looks like Ill be sticking with Wyze outlets for the future. Disclaimer: I ordered these to run on my Home Assistant (HA); I have not tried using them with any other system or integration. This review is for the S40 Wifi Plugs. TLDR; I liked the 2 pack of S40 plugs enough to buy another 4 pack and also suggest them to my brother. For anyone running Home Assistant, the setup isnt that horrible, but you are going to have to use the eWeLink app for the initial setup to your network. Additionally, you can get them to be on a local LAN (and not on the cloud) but it will involve some Googling, reading, and some work to get it done. The initial (app) setup was smooth and getting things to work on HA only took a couple of more minutes after doing a little Googling. The energy monitoring seems to be fairly accurate in the sense that a 60-watt LED light was reading approximately 58 watts in HA, but I wasnt proactive enough to verify with the Fluke or Kill-A-Watt yet. (Ill do that and update this review at a later date) At this juncture, Im more concerned about reading energy draw vs no energy draw in order to act as a trigger instead of monitoring energy usage (I monitor consumption at the breaker panel, so I dont really need to do it at the component level yet). The only drawback that I have encountered thus far; if you wish to remove a plug from one network and use it with another, you MUST first go into the eWeLink app and remove it while it is still in the original network before trying to move it to another location (with a different network). In my experience, if you do not perform this step first (and attempt to remove it from the app when the plug is at a different location), the plug WILL NOT turn on nor will you be able to re-enter pairing mode. Im not sure why it was acting like this, but when I returned it to the original wifi network, I was able to get it working without any problems. My original experience with Sonoff was with an S40 Lite Zigbee model and it frustrated me to the point of wanting to chuck it out the window and steered clear of their products for a good while. Thankfully, these (S40 wifi variant) was much easier to play with and my gamble paid off; resulting in me ordering a 4 pack to use within my HA ecosystem as well.

If you care about power monitoring function and/or potential to convert to Tasmota firmware, this is a serious candidate. Other than that, there may be better option around, e.g., TPLink HS103 (15A, no power monitoring) which is cheaper, has better software support and from a reputable manufacture (and UL listed). Now to get Tasmato firmware you need to have a USB-serial converter with 3.3v supply. You need to disassemble (and void warranty) the plug and solder 4 wire to connect to the serial, with the risk of destroying the soldering pad (I did on one of the VCC pad). All these are not really for average users. But if you went all the way through you got something really cool to play with.

These plug are a nice size and appearance. They come part well if you want to flash it. Flashing it is super easy with a decent jig. Be warned the breakout test pads lift easy if you try to solder directly to the pads. It was faster to print a jig then it was to fix it after the rx pad tore off.

Tried for days to pair and almost returned them. Most only searches so older versions of the app and the app is not intuitive at all. It is very picky with how your wifi is set up. The Name(ssid) and passwords Can Not have any spaces or special characters. This was a challenge because we are not able to change these without have to re setup all our other devices. Some are security cameras that are very difficult to get to (26 high and 1/4 mile from our router). Our router is only 2.4ghz but the app kept acting as though we were trying to connect to a 5ghz router. Ultimately we had to add a Guest Account named Letters only and set the password with the same restrictions (which makes for a very weak password). Once paired...whew, It seems to be working. The app does Not give the level of detail I was hoping for. It only provides total daily power usage or instantaneous usage. I wanted to see what time the refrigerator defrost heater came on, for how long and how much power it used but the app doesnt do this. With all this considered it is a good value and we may even buy more now that we are able to pair them. One star deducted due to the app, not the switch itself. Although, if the devices continues to work well over time without loosing connectivity or failing we will update to full 5 stars. We were able to determine the fridge pulls about 1amp/120watts while the compressor is running and a total usage of about 0.9kw over 24hrs. The hair drying on high heat and fan pulls over 13amps/1600watts which is almost the max rating of the device. Be careful not to overload. Only ran for a moment so cant speak to how long it can handle this level of current draw. Lastly the basic math calculation is not 100% accurate which should be very easy to accomplish. Volts x Amps = Watts. The device measures the amps and the volts and calculates the watts. They were reasonably close but not perfect. See image attached, should be 126 watts.

I bought a single S31 to figure which of my appliances was the most power-draining. What I did is simply use the single S31 power plug to monitor each suspect appliance for 2-3 days. The Android App has a kWh power consumption meter which you can start and stop. I was able to find out that my refrigerator was actually the culprit, using about 2kWh a day. I would have given the S31 a 5-star but for the fact that the software app is not the most intuitive to use. But it does the job and the S31 plug itself is only $15.

I bought this as an inexpensive way to meter how much amperage my computer desk pulled at peak load, as well as other things like AC units, coffee machines, etc. it faithfully shows amps and watts of the load. The problem is it’s a “smart” switch which you can toggle on or off, or set automated “scenes”. In addition it has “inching” auto triggers. Even with nothing defined for the automated toggles the logs still show “device triggered” or “scene triggered” at seeming random intervals, which is really inconvenient if you’re using it at the time. Latest firmware did not fix this behavior. I’d recommend only using for short duration active metering and then removing from your path.

Easy to pair and get it working. Alexa, lights on, Alexa lights off! This plug is very handy! I am going to use it for my Christmas tree when its time! Looking forward to not having to struggle with the outlet each night.

Works well with Home Assistant.

Pros: Flashable Affordable Easy to use Compatible with Amazon Alexa, Google Assistant, and IFTTT Power monitoring feature Cons: Too big it cover 2 gauge outlets Not as fast as some other smart plugs Does not support 5GHz Wi-Fi To flash a Sonoff S31 with Tasmota, you will need the following: A Sonoff S31 smart plug A USB to TTL adapter A micro USB cable A computer with a terminal emulator Once you have gathered your materials, follow these steps: Disconnect the Sonoff S31 from power. Open the Sonoff S31 and expose the PCB. Locate the GPIO0 button and the TX and RX pins. Connect the TX pin of the USB to TTL adapter to the RX pin of the Sonoff S31. Connect the RX pin of the USB to TTL adapter to the TX pin of the Sonoff S31. Connect the ground pin of the USB to TTL adapter to the ground pin of the Sonoff S31. Connect the 3.3V pin of the USB to TTL adapter to the 3.3V pin of the Sonoff S31. Connect the USB to TTL adapter to your computer. Open a terminal emulator and set the baud rate to 115200. Enter the following command to enter bootloader mode: Press the GPIO0 button and hold it down. While holding down the GPIO0 button, plug the Sonoff S31 into a power outlet. Release the GPIO0 button after a few seconds. The Sonoff S31 should now be in bootloader mode. Use the terminal emulator to upload the Tasmota firmware to the Sonoff S31. Once the Tasmota firmware has been uploaded, the Sonoff S31 will reboot. The Sonoff S31 will now be running Tasmota.

My wifi auto switches your devices between 2.4GHz and 5GHz, so I cant use this switch unless I dedicate a an old phone. I put my phone on the 2.4GHz band to install it and it worked. However, I cant leave my phone on that band. When I switched back, I couldnt connect to the device. I have other smart devices that require 2.4GHz signal in the house but not on your phone. Bad software design.