FoxESS Community - Owners & Installers Forum

Anybody able to explain this:

I have battery charging Time Period 1 set to 00:30 to 07:30 with Enable charge from grid off, Time Period 2 set to 04:30 to 07:30 with Enable charge from grid on, and I start from an SoC of 65%, so the battery charges to 100% by 05:55. From 00:30 to 04:30 I have a Discharge Power of 0.12 kW and Output Power of 0.8 kW, but from 05:55 to 07:30, Discharge Power is zero and Output Power is -0.2 kW.

I was hoping for discharge from 00:30 to 04:30 to be zero or so, but I can see the SoC droop significantly, about 3% over that 4 hours. But it looks like there's no obvious droop after the battery is fully charged and, from the negative Output power, its inverter-charger is running off the grid. But why would it run off the battery at 65%, but off the grid at 100%?

Graham

Well, I changed Time Period 2 to 00:30 to 07:30 with Enable charge from grid on. Now there's no time for the battery SoC to droop before it starts to charge, and it does not look like there's any charge going into or out of the battery after it reaches 100 %.

That helps what I'm trying to see - where to set Max SoC to minimize both the re-selling of power imported overnight and the importing of power in the day - because it makes calculating what I used directly overnight easier and, hopefully, more accurate.

I can't see any disadvantages to charging at the start of the low tariff period, over leaving it till later, now that I understand how to stop the battery discharging in that period.

But it still seems a bit of a mystery why there's drain on the battery before it's charge and not after. Maybe it's to do with whether Enable charge from grid is on or off in the period set.

Graham