I have a time of use contract with hourly pricing, based on the day-ahead electricity market. So I also wanted to schedule charging, but I was somewhat disappointed that
- my charging station has no scheduling feature built-in
- my EV does have settings for this, but they act more as a suggestion. It would often charge when I didn't want it to.
Fortunately the charging station does support being controlled over modbus tcp/ip, so I was able to write some code and run it on a Rasperry Pi to control it. My control system fetches the prices and enables charging whenever they are below the configured maximum.
However, I now find that (because of my obsession with optimizing this) it is still very far from a hands-off solution. I find myself doing this:
- check electricity prices manually
- check car state of charge manually
- if prices are going to dip very low, figure out how much time will be needed to charge to 80%
- if prices are high, figure out whether I need to do a minimal top up anyway and how much, based on how much I think I'm going to drive
- choose a maximum price such that charging will be enabled during a sufficient amount of hours, based on the above
The main thing that's missing to properly automate this is a way to retrieve the EV's state of charge. But a charging station for home use will typically only support a simple PWM signal to tell the car how much current it can draw. No other communication is possible unless the charging station supports ISO 15118. Mine doesn't :-(
Thanks! I had no trouble setting up the app with my car. This looks like it covers what most EV owners in Europe would need to optimize their electricity bill.
What I'm still missing here is a way to reserve some battery capacity to take advantage of exceptionally low prices. I'm fine with charging to 60% for daily usage. Charging to 80% could be postponed until the market offers a really good deal.
Perhaps I'm irrationally over-optimizing just to get few more euro of savings... But it also feels good to soak up renewable energy when it is plentiful.
I use home assistant to charge automatically when I want, to the level I want. Though to make it work both my charger and car are somewhat supported by hacs repos.
I live in Flanders, Belgium. Half of households here have a digital meter by now, which makes such contracts technically possible. And the government has made it mandatory for the large energy companies to offer such a "dynamisch elektriciteitscontract".
The reason for all that is to encourage more efficient usage of the grid and renewables.
- my charging station has no scheduling feature built-in
- my EV does have settings for this, but they act more as a suggestion. It would often charge when I didn't want it to.
Fortunately the charging station does support being controlled over modbus tcp/ip, so I was able to write some code and run it on a Rasperry Pi to control it. My control system fetches the prices and enables charging whenever they are below the configured maximum.
However, I now find that (because of my obsession with optimizing this) it is still very far from a hands-off solution. I find myself doing this:
- check electricity prices manually
- check car state of charge manually
- if prices are going to dip very low, figure out how much time will be needed to charge to 80%
- if prices are high, figure out whether I need to do a minimal top up anyway and how much, based on how much I think I'm going to drive
- choose a maximum price such that charging will be enabled during a sufficient amount of hours, based on the above
The main thing that's missing to properly automate this is a way to retrieve the EV's state of charge. But a charging station for home use will typically only support a simple PWM signal to tell the car how much current it can draw. No other communication is possible unless the charging station supports ISO 15118. Mine doesn't :-(