Hi all, let me introduce myself first. I'm an Electrical Engineer and a colleague of mine and I are working on a project relating to Electric Vehicles (EVs) and their chargers.
To be more specific, the project we're working on involves us designing a custom controller for the EV chargers to allow them to be connected to the internet (so basically an IoT charger). What we need out of the controller is to be able to control the charger (turn it on, off, or limit it in one way or another) and read the current charge of the vehicle. So, what we're basically trying to do is making an existing EV charger smart. The plug that we aim to use is the J1772 plug.
We've been looking at the project and we think that an ESP32 would probably be a good fit for this project as it has a built in WiFi module and so we would not need any additional circuitry for an ESP01 WiFi module. However, this is as far as we've gotten as we're really not sure at all how to get readings from the EV itself on how much it has charged, or how to control the charger. We have a solid understanding of the Arduino IDE and once we have a pretty small example of the reading getting to the Arduino we're more than sure that we can develop a custom controller that does that.
Are there any advice that this forum can give us on how to get readings on an EV's state from an already built charger?
There are a lot of different EVs and a lot of different chargers. The chances of there being a general solution which can control any or all of them is very remote.
So what is the specification of the charger you're interested in? Most EVs that use that SAE J1772 plug have much of the charging control in the EV itself and the standard comms protocol doesn't include communicating the EVs charge state.
I would suggest you research the different chargers you want to control, get schematics, working units etc to thoroughly check them out. At this point generate a proposed schematic and at that point pic the micro that is capable of doing what you want. You may be trying to put a size 14 into a size 7 shoe.
If you look at the battery management chips from Analog devices , some have I2C interfaces .
EV’s usually have their own charger control systems due to the need to control cooling, capacity , cell balancing and so on .
Depends on your EV , but information likely to the available over canbus - cars seem to know how much charge they have .
You need to do some research !!!
The EVSE (electric vehicle supply equipment) is a glorified AC switch. All it needs to do is provide line current to the car when the car is ready to charge. The OpenEVSE project is an example of how to design one. https://www.openevse.com/
The duty-cycle of the 'pilot' signal (+12/-12 1 kHz PWM) from the EVSE tells the car how much current is available from the EVSE. The car puts resistors across the signal to change the positive voltage to tell the EVSE if it is ready to get power. When the car is ready, the EVSE connects the line voltage to the car.