Looking for a multi output, clean contact relay unit


I have a little project on the horizon that I’m trying to find a voltage free relay output device for. It would be ideal if this would be powered by 12v DC.

I know there are a number of ESP relays available but I would prefer something from a reputable manufacturer. Price isn’t that important as long as it works and it looks like a good quality product and not a circuit board stuck to a relay.

WiFi would be preferable but some sort of Zigbee device would be acceptable if the manufacturer makes their own hub that can integrate seamlessly into Home Assistant. It would also be ideal if their hub accepted standard Zigbee devices or at the very least they had a good range of things like multi coloured bulbs etc.

Voltage free clean contacts would be best but even a unit that has multiple outputs that can supplied by 12v and supply 12v on the outputs would be more useful than what I’ve been able to find myself.

I’ve used some of the Shelly units and I like them but the only one that gives a clean output is the plus 1. I know the Uni gives 2 clean outputs but the 100mA limit on them is very restrictive.

I found the Sonoff 4ch pro r3 but it’s currently unavailable on Amazon in the UK and in any event, it looks like it needs to be set up with Ewelink then Ewelink gets set up as an add on and I’d prefer something that was as seamless as Shelly.

On my own system I mostly use Zigbee but for the next project and potentially others I’d rather stick to WiFi devices if possible, or at least find a more stable way to use Zigbee!

I’m not sure if it’s my coordinator or my devices, but I regularly find I have to remove my dongle to get everything to connect after a reboot and occasionally I have to go and switch off my smart plugs too. For projects I’m not going to be within arm’s reach of, I want to set them up to work and not have to worry about them stopping for random reasons.

These are called “Dry contacts”.
What are you planning to control with the relay? How many poles do you need?

I use relays daily, clean contacts and dry contacts are interchangeable.

In this instance they’ll be used to switch low voltage circuits (12v or 24v DC). I’d like something with clean contacts because they can be used for signaling or power switching using an external power source.

I don’t need more than one pole for each relay. For the upcoming project I only need 2 individual relay outputs but honestly I could see a use for anything up to 8 relay outputs. Obviously you can just use multiple single /double output devices but even something similar to the Sonoff 4CH Pro R3 I mentioned above but that would integrate directly with Home Assistant without the need to connect to any external service - even if only for the initial setup - would be useful.

For my own setup at home I went with zigbee for the (I thought) compatibility of being able to just integrate all zigbee devices through one channel, but as I mentioned I’ve just had too many little random failures where I have to remove my coordinator and reattach, or even worse power cycle the devices sometimes to get them to reconnect.

I have ordered a new dongle https://amzn.eu/d/56Dxl8G to see if that improves things, but I’ve got a few Shelly wifi devices that have been completely flawless so I’d love to find a WiFi multi channel relay that has clean contacts rather than switched voltage outputs.

Well, that makes a difference. It also narrows down the range of device suggestions because from your first post we didn’t know if you were controlling LEDs or a 100HP electric air handler.

I have three Sonoff 4ch R3’s that control my lawn irrigation valves. They use the ESP8266, so just flash them with ESPHome. No connecting them to Sonoff at all.

Do you mean the 4ch R3 or the 4ch pro r3?

The issue is that the 4ch pro r3 doesn’t seem to be currently available. Sonoff’s website just links to Amazon and the device is listed as unavailable, not even as out of stock.

There is a similar looking mhcozy 4 channel relay that also uses Ewelink Amazon.co.uk that possibly has a similar hardware setup.

Looking at the standard 4ch R3 the wiring diagrams looks like it just provides a single switched mains terminal for each output but maybe you can advise that it can also be used as even a switched low voltage supply?

This is why I’d prefer just a plain old C NO NC relay output because then you can use it for anything you like.

The Shelly Uni looks great apart from the miniscule 100mA rated limit on the outputs.

It’s available in the US and looks like it would do what you want.

Ewelink is no problem. I use SonoffLan, a custom component for Home Assistant that lets you use Sonoff Devices without changing the eWeLink firmware, and best of all, it doesn’t use the cloud either (except for initial setup).

Here’s a tutorial on how to use it.

I picked up one of the MHCozy relays and it almost works a treat.

I set it up with the Ewelink app and had it working “offline” when both the device and the HA server/Ewelink addon were offline but it didn’t at all like it if the Ewelink addon was online but the relay wasn’t (I blocked its outgoing WAN connection with my firewall)
That’s a pretty niche setup, but I’m sure I’m not alone in giving Home Assistant internet access but not the devices it’s controlling.

Thanks for the tip about the Sonoff component. I gave it a try and it works even closer to perfectly. I can now fully drop all packets coming from the relay yet it still works perfectly provided it’s on the same VLAN as Home Assistant.
I’ve had a quick look at mdns which is apparently how the devices find each other but from what I can see, Miktotik doesn’t support it but having the relay on my Home Assistant VLAN with a static ip isn’t the end of the world because I can still stop it communicating with anything.

The MHCozy relay seems pretty sturdy and well made in case anyone is looking for one. Time will tell how the relays will last, I’ve read some bad things about them and they’re dirt cheap (made by Songle) but the board itself seems really well made with good solid soldering.

I’ve looked around a bit for similar things and they aren’t very common for Zigbee. I ended up with the MHcozy too. 4-kanaals zigbee relais schakelaar | We ❤️ Smart! | ROBBshop It looks like this is the same 4 ch mhcozy rebranded and put in a 3d printed box. I got mine from Alixpress but if you prefer to buy from a reputed reseller in a country with good consumer protection this might be an idea.

Similar but not quite the same. The button stalks on the MHCozy are longer and the power terminals are beside the relay terminals and not opposite. There also looks to be a reset button on the one you linked as well as what looks like some programming headers. The MHCozy is sadly lacking ANY easy way to flash new firmware without some very fiddly soldering

The one I have is single channel, but it has pushbuttons too, one for reset/pair mode and one for manual relay operation, which seems to correspond to the one and four buttons on the Robb unit.The main difference I see with mine is that the Zigbee PCB that is soldered onto the relay PCB is white in color. Mine is green.