springfall2008
Battery max charge hysterisis
Is your feature request related to a problem? Please describe. My FoxESS inverter allows a max SoC of 100% but once achieved the charge current reduces to 0A until charge drops back below 97%
Describe the solution you'd like Either a user configurable or baked in hysterisis to stop Predbat force charging when BMS won't allow it.
Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.
Additional context
Interesting, it maybe possible to model. A workaround maybe to set a charge curve and make 97-100% be quite slow, it won't be fully accurate but will steer away from going to 100%.
The plan above however only shows charging to 100% once?
In the plan above the 100% target had already been acheived earlier in the day but had subsequently dropped back down to 99% but the max chaarge current was 0A. I'll try and get some move evidence but have restarted HA several times since then. Not sure if my apps.yaml will help but I've included it.
There will be quite a significant slowdown from about 97% upwards the first time through.
TBH I had never noticed that the BMS charge rate stays at zero until you drop below 97%, but since I only ever go up to 100% on calibration days it's not something I've ever focussed on (most other days I stay in the 20%-87% range).
This is the battery charge curve that I personally use, it'll hopefully be right for a 50 Amp inverter (KH series). For the 40A H series you'd need to adjust it. In practice the BMS charge rate does not limit my system until the upper end of the range, since my inverter is only 7kW, which means that it won't go above 27A in any case (and normally I charge at the slowest possible speed for the time available).
# Some batteries tail off their charge rate at high soc%
# enter the charging curve here as a % of the max charge rate for each soc percentage.
# the default is 1.0 (full power)
#battery_discharge_power_curve:
# 4: 1.0
# Based on the ECS4800 Charge curve with 50Amps as 1.0 https://www.foxesscommunity.com/viewtopic.php?p=4554#p4554 (Linear from 80%-97% then drops abruptly).
battery_charge_power_curve:
100 : 0.05
99 : 0.10
98 : 0.20
97 : 0.32
96 : 0.36
95 : 0.40
94 : 0.44
93 : 0.48
92 : 0.52
91 : 0.56
90 : 0.60
89 : 0.64
88 : 0.68
87 : 0.72
86 : 0.76
85 : 0.80
84 : 0.84
83 : 0.88
82 : 0.92
81 : 0.96
Just adding tis here. Not sure if it will hel but you can see battery was full and as soon as it dropped to 99%, Predbat updated to force charge.
I have a SolaX inverter and battery which exhibits a similar behaviour.
It will charge up to 100% then as soon as the charging session stops, it drops back to 99%.
Predbat then issues another forced charge session, but the battery won't actually charge, it just sits there. Notice in the screenshot below, it's enabled force charge on the inverter settings, but the battery shows as not charging.
It does the same charging from solar as well. In my case it won't begin charging the battery again until the level drops to 98%.
I agree that it would be nice to have some sort of programmable hysteresis as suggested above. For example have a setting where new charge sessions can't be started until the battery has dropped below a certain SoC %. That would allow it to charge up to 100% in the current session, but then prevent predbat from trying to issue a fresh charge command when the SoC is simply rebounding slightly.
