SONOFF DW2 WiFi Wireless Door Window Alarm Sensor with Phone Alerts, No Hub Required, Works with Alexa & Google Home, Low-battery Reminder, 2.4GHz WiFi Connectivity

works a treat, the single AA battery has lasted well over and year, it has not lost connection once. And it triggers every day to alert me via Google Home. Considering it requires no bridge device (as it's wifi connected) its a fantastic bit of quick for a good price

I was impressed how easily these were to set up electronically. Although I did have a little difficulty in siting the one on a door that did not close flush with the frame as both the items need to be lined up flush. Initially I was quite happy with the setup. So much so that I nearly ordered more. However, 24 hrs later and I was being advised to change the batteries. after a further 12 hrs they stopped working. Maybe I had a bad batch of batteries. Bought new batteries and fitted them. Hey presto everything working fine again. That was short lived. 12 hrs later I'm being advised to change the batteries. So unless you intend to change the batteries every day then they probably aren't what you want. Easy to set up but a nightmare to maintain! I would have expected the batteries to last at least a month! Steer Clear!

This Sonoff door/window switch worked fine initially but this morning, 42 days after I installed it, it is completely dead. No LED light, flashing or on solid! I replaced the batteries but still no good. I have now found out that the Returns Policy is for up to 30 days! So it didn't last even 2 weeks past the Returns cut-off period! If I order another one I am worried about how long that will last! Has anyone else had this problem or have I just been unlucky? UPDATE. Replaced the battery (again) and re-paired it - and it works again! Not sure what the problem was, but all okay now and it is behaving itself perfectly! Since buying this one I have bought another one and they are both working fine. One turns on a light in the understairs cupboard and the second one gives me an audible warning and flashes some lights (via Alexa) that the outer front door has been opened. I might get another one for my back door! :) Edited this review to show 4 stars out of five!

Unless the unit I got is somehow defective (but I'm not going to buy another one to try it), this product is a joke. Battery life is terrible, the first set of batteries (2xAAA) I used lasted for about 7 days. The second set only lasted less than 3 days! Look at the graph taken from Home Assistant, the one named as "Fridge Door Battery" is this Sonoff sensor. Battery went down to 70% after just a few hours, and then became erratic until was completely drained a few hours later. Compare to the other graph (Contact Sensor Batter), this is from another similar sensor (different brand), but the battery has been solidly constant at 100% during the last 3 days. Battery is supposed to last for about a year in these kind of sensors. I already spent more in batteries than the sensor itself, and now I'm with a useless piece of plastic. The sensor itself works well when is powered Update 03/10: Sonoff after-sales contacted me and after a few tests, they recognised the product was defective. They offered sending me a new sensor, but since I've already got another one, I opted for a refund, which they promptly did.

I bought this product with a attempt of simply trying to expand the functionality of my current sonoff light switch. However after reading some negative comments about it, I have to say it did almost put me off from buying this great product I have been using this for almost 2 weeks and I have never come across with any issues what so ever. Setup is piece of cake, no wires just battery powered and simply stick on to the door with the supplied 3m sticky pad. What amaze me the most is the responsiveness, as you can see from my video, it turn on/off almost instantly. For those who used the ewelink app, this is not going to any issues, you just simply setup the the device to trigger an action on your WiFi switch using 'scene'. Please don't let the negative comments put you off buying this great product and try it out yourself. I will give me more stars if I could simply because the functionality/cost.

Couldn’t connect to my SONOFF zigbee hub.

If, like me, you have kids that leave the freezer open, and you go to it the next day and find all your expensive meats thawed out, it drives me crazy I have to throw all that meat in the bin. Well no more wasted meat!!! I like this because..... - Easy to install - Notifies me via notification - Simple and effective - Low cost - Two AAA batteries and install within seconds. I use amazon basics researchable batteries, these are great too. Hope you like it like me :) Well done sonoff, big fan!

So pleased when it worked at first! Now it's eaten 4 AA Duracell batteries in its first week. Absolutely not fit for purpose.....used outside on garage door.

Using this for years now , build a mailbox warning system with it ;)

Returned, they drain batteries like crazy. Older model lasted 8 months, these did not last a week.

Cómo se vaya la luz y se corte el wifi ya no reconectan, hay que quitarle las pilas y ponerlas de nuevo. Edito, el vendedor se puso en contacto conmigo y se han solucionado los problemas que tenía, gran servicio técnico

Product as described

Come tutti i prodotti serie Sonoff, nulla da dire. Il prodotto fa egregiamente il suo lavoro.