To start with what is an EVSE?
“Electric Vehicle Supply equipment” also known as the charger.
Why should anyone care about EV’s in ZA?
Well, because of the following combination of factors:
ZA vehicle manufacture contributes around 7% to the GDP.
The domestic market is too small to support this industry without exports.
Export destinations will start banning ICE vehicles imports in 2030.
Ergo, local vehicle manufacture will become EV centric and the government will incentivise, where they presently discouraging sales.
So with that out of the way, I started looking into what’s in the charger.
Well, it turns out not much.
All the fancy bits of the charger are in the car, the charger is basically a switch.
Except really for one clever thing.
Most recent EV’s can take all the current you can throw at them. The thing is your charging point is limited by its own cabling and supply. So it has to tell the car about its limitation so that the charging circuitry is not overloaded.
These AC chargers range from about 7kW to 50kW ( I am leaving out DC chargers deliberately).
How is this achieved?
Well, basically one of the pins in the charging cable carries a PWM signal to the car. And it is that square wave modulation that informs the car how much current to draw.
Well, this leaves a lot of room to play, for example, you plug in a second vehicle into the charging point and the power draw per vehicle can be halved etc.
But I got to thinking about solar charging.
Considering the Victron system: Some people like to keep their batteries charged, some like to use the top 30%, some schedule charging, some people want to divert excess solar power, some people want to limit grid import /export etc. There is a myriad of customisations - all valid.
I think that there is a space here for a manipulated PWM output that reflects a user’s customised charging preferences, a whole lot better than just 7kW or 22kW or 50kW.
I think a DIY solution and a bit of Node-red or something and you could have a car charger that delivers 0 to 50kW and everywhere in between to match your solar production and your own custom requirements. Hell, these days they can even throw the weather forecast into the mix from what I understand.
Well, just spit-balling to hopefully inspire someone to get ahead of the curve … or even Victron?
Edit: I found this, so maybe there is hope:
Edit Edit: But I think it’s not the hardware that is important, it is that PWM signal. As it is a standard protocol any hardware should be able to be manipulated.