120v powered isolated dry contact recommendations?

Can anyone suggest a Z-Wave or WiFi device that I can use to auto start a generator? I’d like a NO dry contact that is powered with 120v. I can find several 120v ac switched relays but I need to Close the relay and short to ground. I saw several folks recommend a product that appears to no longer be available.

When my off grid batteries go low I need to close the contact (sort to ground) to start the generator and then open the contact with the batteries are charged or the sun is up (solar).

Where in the world are you located? Z-Wave offerings are region specific.

Something like this tied to an 8266 should do what you want… https://arduinogetstarted.com/tutorials/arduino-relay

They are readily available on eBay and Ali express.

You could probably configure tasmota or esp home to do what you want.

I found a North American Z-Wave product that is triggered by 12-24 volts but handles 120 volts at 15 amps dry contact.

Shelly 1 is the perfect product for this.

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There are some Z-Wave products that could be modified (e.g. Fibaro Smart Implant - but this would need an external relay), but it’s probably easier to use something like a Sonoff or indeed the Shelly already suggested.

The Sonoff 4CH Pro has ‘dry’ CO relays, and can be powered from mains or 12v (or at least the UK variant can…), and I’ve used a 4CH flashed with Tasmota and modifed to add an external sensor input on a spare ESP8266 pin. All other Sonoff’s have relays connected to mains (‘hot’/ Phase, not Neutral).

It largely depends on:

  • What connectivity can you get where the genset is - WLAN or Z-Wave?
  • What is your electronics knowledge? out of the box Shelly, flash a Sonoff with Tasmota, or homebrew ESP?
  • What level of integration is needed? Simple single switch, monitor state, full measurement with ADC, clamp meter current measurement…

I love this community!! Thank you so much for your responses.

Answers to questions
I’m located in the USA
Connectivity Yes WiFi or Z-Wave.
I’m happy to flash a sonoff or and ESP if I had the time but I’m in the midst of building my home and this is the back up generator for the solar system. I’m off grid. Right now I’m looking at the simplicity of the Shelly. But it looks like it is a relay and would switch the 110v rather than trigger an Isolated dry contact. The Sonoff looks like it is also a 110v switched relay.
Level of Integration: I will be monitoring the battery bank voltage and when it gets I need to close the dry contacts and keep the contact closed until the voltage gets sufficiently high and then open the contact. I already have the Battery Management system tied into openHAB, so I have all that info already.

I have 110v power available to power the device but will not be passing 110v to the generator only shorting the line to ground.

I’d like to power the device with 110v rather than battery as this is located in a shipping container in the winter and I find the battery devices struggle in the cold and the Z-wave signals also struggle to penetrate the steel walls of the shipping container. If it is line powered the signal penetrates better and is more reliable. WiFi seems to penetrate just fine.

It looks like the Fibaro Smart implant may work but It would need an additional relay.

Thanks for all your advice!!

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The Shelly 1 definitely has a dry contact - the I and O are totally separated from the mains power on L, SW and N.

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Perfect thank you