Connecting a Shelly to a Dumb EV charger

[huwy123]

Hi there,
Does anyone have any experience of using a shelly device to add smart functionality to a "dumb" chargemaster EV charger.
I've found some instructions online and the process seems simple enough. You power the Shelly off the mains supply and run the pilot wire through the Shelly. The only change is the model of Shelly they used has changed with the new one having a new "12v" terminals.
The Shelly is connected to the pilot signal to notify the EV charger to start/stop charging (it does not cut power directly).
I presume the Shelly should be wired as below as the mains supply is not 12v?
Appreciate any advice.
H

 

[Why Not Indeed]

If I were you, I would disconnect what you reckon the pilot wire is and then attempt to charge. If it fails to charge, then your proposal to control it with the Shelley should work.

 

[Adam_151]

What you might find is that disconnecting the control pilot will stop the charge, but it might not auto start when reconnecting it, you may or may not find you can overcome it by running it through a changeover contact instead, with it being disconnected from the vehile and instead connected to earth through a 2.74K resister in series with a diode* (to mimic a vehile connected, but not requesting a charge) you might have to play round with it on the bench (by the way if you parallel a 1.3k resister across the first, that mimics a vehicle requesting a charge).

I'd also not supply the shelly straight off the incomming terminals of the EVSE, these are normally on a 32A or 40A cirucit. I'd look at putting somehting like a 2A mcb, or fuse in a red spot carrier to protect it, just incase something goes awry on the logic board of it

*The diode is there to distinguish a delibrate resistance, from dampness in the connector, the use of earth rather than a second control coductor is so that it relies on earth continuity being intact between the EVSE and the vehicle to be able to communicate a state in which the power would turn on