In Part 1, friend of Automated Home, MarkB, started to convert his smart home over to using Shelly modules. Now in Part 2 he uses more Shelly hardware, this time to turn his dumb EV charger into a smart one…
I will start this with the usual warning – This is an illustration of how I am using Shelly devices and it is not a detailed tutorial. Mains Voltage can kill, cause serious injury or damage to property and equipment. Please ensure you only conduct work you are competent in or trained to do so and comply with local regulations.
I have been using a PodPoint EV charger for more than 7 years. My current EV is a 30kWh Nissan Leaf and it is our primary car, covering the majority of our household miles. It gets plugged in every other day to top up the battery. Recently I switched to a day/night tariff from a local electric provider and wanted to ensure I shift as much of my load to the night time tariff.
The Leaf has an inbuilt charging schedule but I wanted something a bit smarter. So I decided to investigate what I could do with my charger or EVSE (Electric Vehicle Supply Equipment) to give it its proper title.
I had asked PodPoint some time ago if the unit had any Smart upgrade path but unfortunately nothing was available. This is unfortunate as we see how units like the Myenergi Zappi can play an integral part in domestic power consumption management.
I had investigated building my own EVSE at one stage so knew something about their general operating principles. First point to note that an EVSE is not a charger, the actual 240v charger is built into the car. An EVSE is basically a way of connecting 240v to the car in a safe manner. The connection consists of a live, neutral, earth, a control pilot and a proximity pilot. The mains connection to my EVSE unit is rated at 32A or 7.2kw despite the car only being able to utilise 16A or 3.6kw via its onboard charger.
When the charging cable is not connected to a vehicle the EVSE cuts the power and only restores it once a safe connection has been established with a vehicle via the proximity pilot and an appropriate signal from the control pilot. If you want to know more about how this works I suggest watching this video.
Interrupting the control pilot line means the car cannot talk to the EVSE and charging will not start. The car knows a cable is connected using the proximity pilot so you cannot drive off. I wanted to avoid the 240v side of the EVSE so utilising the control pilot seemed like the logical approach. I used a Shelly 1 with its dry/volt free contacts to interrupt the control pilot.
Left: EVSE Cover removed and Shelly 1. Right: Control Pilot connected to Dry contacts O/I, device powered via 240v from incoming power. Bootlace crimps used on all stranded cables.
I set up two scenes schedules so it automatically closes the control pilot at 02:00 when my night time tariff kicks in and opens the circuit at 09:00 when the tariff ends. It also sends me a courtesy email to let me know what has happened. We now plug the car in during the day and the Shelly takes care of charging at night. If I need a boost during the day I can just ask Alexa or use the app. I could also fit a push button to EVSE to toggle the Shelly if we needed to start a charge but opted not to do this at this stage.
I have also added a number of Shelly EM’s to monitor power consumption across the house and generation of my solar PV. This allows me to see what is consuming power, when and just how much.
Consumer unit with 3 Shelly 1PM’s controlling tumble dryer, washing machine and immersion water heater, along with a Shelly EM (bottom left), monitoring the EV circuit and the whole house consumption or export via 2 CT clamps, all neatly accommodated inside a consumer unit.
Left: EV charger status (off) and power consumption, unit drawing 5w in stand by. Right: EV power consumption history, 22.74kWh taken, adding ~85 miles at £0.08 per kWh.
I could harness Shelly’s DDD (Direct Device to Device) communication feature to send a command when the Solar generation hits 2kW as an example, turning on the EV charger relay. Ok, it’s not going to instruct the car to throttle back the charging rate to match available generation but it’s still a significant contribution, if you needed that power matching functionality you need to spend >£1,000 on a dedicated Smart charger not £50 on Shelly devices!
This is just another example of how I am using Shelly to optimise energy consumption and reduce my costs.
Last update on 2021-10-03 / Affiliate links / Images from Amazon Product Advertising API
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