From my Solax inverter I can read the battery % remaining and also the power flowing to/from the battery. The battery % alone gives power available to approx 0.1kWh (~10kWh system), but it would be nice to get a bit more accuracy if possible.
I can turn the power to/from battery to a kWh figure using a ‘Power to kWh’ conversion, which gives a more precise figure for power in the battery, but that figure drifts over a few days due to power losses (you don’t get back quite as much as you put in).
What I’d like to do is combine the two - have a feed for ‘power left in battery’ - maybe in Wh so it can be more accurate. When the battery percentage changes (say from 22% to 23%), set the feed to the known value of battery remaining (2300Wh in this case). Then while the battery percent sits at 23%, use the ‘battery power (W) + Power to kWh’ to track the fine changes in battery level until the next change in percentage happens and corrects any drift.
Right now, I can’t see a way to do this in feed/input processing, and I’m wondering if there is something I am missing. If it’s not possible I can probably hack it together in my python data input script, but I was hoping to avoid that and keep the data input simple.