220V Outlet Control for Charging Electric Vehicle

I have 220V running into my garage so that I can run a heater, a Mill, and an Arc Welder. Now, were looking at needing to charge an electric vehicle. I can't do all of these activities at once, and don't want to. In my area, I need to charge a vehicle at certain off-peak hours. I want to plug in the vehicle whenever I want, but not have it charge until off-peak hours. I would think that I will just splice into my existing 220V outlet and add another outlet dedicated to the electric vehicle that I can control via HE to restrict its charging to specific hours. What Z-Wave device do you recommend to limit these 220V charging hours. Any other suggestions.
Thank you.

I believe you will need a simple switch function. Either wall mounted or in a module. This switch will control a large relay or perhaps contactor. There is nothing Zigbee or Z-Wave that will handle what is seems in you load requirments.

Depends on the car of course ,but most have scheduling built in to the vehicles system....


I wasn't aware of this but it makes sense. It got me thinking though.....

As a mental exercise (I would not suggest this) there seems to be a pair of lower power contacts in the charging plug (and receptacle). I would think these must make contact or pass a signal to the vehicle (or station) signifying the plug is in place, the high voltage/current circuit can be energized. I'm guessing you don't want to engage and disengage a 220V/30 amp circuit with the plug.

If all this is true you could control the charging (if the car wanted to be charged) by breaking this low power circuit.

My Bolt has 2 time zone program for off peak charging (ex summer/winter)
A quick scan in Amazon for programable chargers resulted in several in the 300-700 range that are wifi and phone app. Didn't spend a lot of time but couldn't find Z-wave or Zigbee. I suppose you could use the Wifi model controlled by home Assistant and link it to Hubitat with a little effort.

Edit: found GE Z-wave 40 amp switch, but I'm sure a driver would have to be developed.

These are on the list of HE compatible devices, found here. So should work out of the box..

1 Like

They driver for the GE switch was recently released. Aeotec also has a similar product that works well with Z-Wave plus.

1 Like

I previously had a 240v heater plug in my garage - I ran an 8/3 years ago to put it in.

Recently my son bought a Tesla model 3 and I was thinking of just splitting the connection and running to both.

Instead I installed a sub-panel so I could put in separate breakers for the car and heater. I also moved the other three 120v ccts I had in the garage to the sub-panel freeing up two breaker slots in my main panel (32 ccts and previously filled).

This worked out even better for me because I had to run a new 20A line to the back yard and I got lucky that I had the open slot in the main panel.

I second or third the fact that the car can do its own scheduling.

If you do want to switch the 240V to the car, I recommend a contactor to switch both HOT lines at the same time and you won’t blow anything if it gets switched off while the car is in the middle of charging.

Another note: while not required by code as far as I can tell, I forked out an additional $80 to install a safety cut off next to the EV outlet. The plug is at the end of the garage while the sub-panel is at the front (house side). In case of something going really wrong, I didn’t want my some to have to go 20 feet to cut the power.

1 Like

Doesn't your car have the ability to program charge times into its on-board computer? My BMW i3 does, and all that you have to do is plug the car in when you park it. The on-board computer will start charging at the programmed time, and I believe that it even adjusts the start/stop time if the battery is so low that it cannot complete the charge during the programmed off-peak time window.

Also worth mentioning is that I've read about some EV car/charger combinations having problems initiating charging when used with a switched power source. Apparently, things go sideways if the cable is plugged into the car before it is plugged into the wall. Just something to check.

I wish that someone would come up with OpenEVSE charger support for Hubitat, but that's another topic.....

Many of the EV chargers also have WiFi and an API so a driver could be written to control the charger.

Agreed on OpenEVSE support.

I agree. Which car and charger are you planning to run @dean ? You may have options to interface directly with either or both.

I made a JuiceBox integration a while back. I don't actually have one to test and maintain it with, so YMMV: GitHub - tomwpublic/hubitat_juiceBox

OpenEVSE doesn't look too bad to add basic functionality, if this is the relevant API @potts.mike or @vreihen . If either of you are running an OpenEVSE setup, are you able to view the status pages for Manual Override and Timers that are described in that API reference?

@tomw I run OpenEVSE today. It's not pretty, but with a combination of MQTT through YAMA and virtual devices, I am able to initiate override and set charge current. Don't have a clean way to get the actual charge current back into hubitat with YAMA though

Unfortunately, the firmware on my OpenEVSE is so old that it doesn't have the newer HTTP API interface, only the RAPI stuff.....

Do you see the value you want on this page?

http://<your openevse ip>/status

Do you see the value you want on this page?

Yes. I do typical stats of interest are:

  • evse_connected
  • amp
  • voltage
  • pilot
  • temp2, temp4
  • vehicle
  • state
  • wattsec

As FYI, here's a snapshot of the output:


1 Like