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I've been putting off setting up some home battery automation to discharge what's left at the end of each day (before recharging on the off-peak overnight rate). I procrastinated as I couldn't be bothered to work out a clever way to avoid discharging energy I'd want to use in the evening. (cont)

10/4/26, 7:03 pm0 reposts0 likes

Jon

@chrt.dev

10 Apr

It's impossible to charge and discharge at the same time, or import and export at the same time from the grid. So if something in the house needs the power, no problem. It will just reduce the power being exported from the battery.

Jon

@chrt.dev

10 Apr

You just need to work this out: At the current state of energy (how many kWh do I have stored, or SoC % * Battery Capacity), how many hours would it take to discharge at max power? Then take your target time, 23:30 for me, and subtract your discharge time from that. 2 hours? Discharge from 21:30

Jon

@chrt.dev

10 Apr

I thought it would need some kind of pattern analysis to predict my expected usage of a given evening. But then I spoke with a good friend of mine, who pointed out that it's much simpler than that.