Battery losing SOC when discharge set to 0W

On days when I don't generate any power, and the battery would otherwise run out of power before the next charging schedule, I want to stop the battery discharging at peak times, this gives me some grid use history at times that are likely for the saving sessions.

Problem is that the SOC seems to just drop when the battery pauses discharging.

I have done this twice now, and both times it's done it, so 2/2 in terms of behaviour. I am aware of SOC issues and drops people have had, but not in a reproducible fashion.

Inverter Model
GIV-HY5.0

Software Version
D0.450-A0.451

Battery Firmware Version
3012

Here is the graph today (battery went from 34% to 19% = 15% lost)

Here is a similar occurrence on 18/11 (battery went from 26% to 15% = 14% lost)

Battery is indoors so shouldn't be getting cold or similar, just seems that the change of behavior causes the SOC to drop about 15%. Seems to do it about 30 minutes after the battery goes idle.

Anyone else seen this/any ideas what it could be that causes it? as far as I can tell the power it loses isn't available later and is just lot to the void.

LordHippos key is the 30mins idle part.
That's the timespan the BMS needs to do its OCV checks measuring idle voltage then readjusting the SOC to where it thinks it should actually be.
It's instead of getting DOC drops at either end.

It can't do it when the battery is busy as the voltages sag. Battery needs to be below 40% and less than 200W load on it from memory.

hoggy So perhaps I am better off trying to hold it at say 40% or a little above it when I try and do this? Stop it trying to adjust the SOC too much.

LordHippos If you find a way of stopping the SOC% being adjusted too much (or too little) I am sure that GE would be very interested!

Woodstock I do feel like it's adjusting too much when it does this process, but next up I will see what it does if I pause it above 50%, according to Hoggy it should not do this process when it's above a certain % SOC/or above a certain usage figure.

I feel like what it's done has lost some power somewhere for no reason, I'll see if I can back this up with actual evidence at some stage.

LordHippos if you have a look at the battery firmwares page on the Givenergy KB I think it tells you which % the OCV checks kick in at.
I know 3013 was higher than 3012 but it also had a habit of bricking BMS's too so...

LordHippos Sorry, I was being facetious. The problem of the SOC% being over/under adjusted is well known to me and has been reported many times. Frustration at its continued existence got the better of me!

The fact that the SOC% adjustment processing was introduced to correct the displayed figure (but can introduce an even greater error) makes it all the more galling.

If you want some background to this have a look at the "New GivEnergy Inverter & BMS Firmware Beta Testing Chat" thread and read my posts through June and July 2023.

There's two similar posts at the moment so for avoidance of doubt as to why the SOC adjusts at all:

hoggy Sadly the third paragraph under the heading "Solution" is perhaps a tad optimistic.

From personal experience "Online OCV" (oxymoron?) mode is much less accurate. On the fly adjustments have not been infrequent and some are far from small!

Woodstock Don't worry, I've not been paying a lot of attention here lately so some of that went over my head originally, but I can see it's similar to the issues other have faced and still plagues a lot of people.

@hoggy pausing battery above 50% SOC does seem to work fine, as I did it today and didn't see any SOC drop, so thanks for the suggestion, I can work with that 🙂