Change in behaviour at min SoC

[Phil M]

Afternoon all,

I've just noticed a change in the way my battery is behaving when it reaches min SoC when there is no sun. It always used to reach min SoC (set at 10%), then it would charge up to 15%, then discharge back to 10% before repeating until the sun shone and it charged above 15%. As of about 6am on the 27th Feb, it no longer charges up to 15% after reaching 10%. This seems a little more normal and I guess reduces battery cycling but I noted that today it's dropped below min SoC. Has anybody noticed anything like this at all? Should I be concerned that the battery is dropping below Min SoC? I guess it could be a firmware update but looking at the version history in Home Assistant, it looks like all of the settings changed 3 hours ago and there is no history before that (I have been doing some work on HA and may have restarted it 3 hours ago).

My kit details are:-

Inverter - KH7
master ver: 1.6
Slave ver: 1.01
ARM Ver: 1.58

Battery - EP11
BMS version 1.006

Thanks in advance!

Phil

[MaterialBarracuda48]

Hi Phil,

That 10% to 15% SoC sounds more like a forced BMS charge, this usually occurs when either very cold, or the cell Voltages are not happy and demand a top up.

If you are in a cold environment, read UK, then this would match up with the change of behavior (sticking at 10%) as it is now milder.

I notice you have the EP11, does your battery have a WARM sticker on the side of it? If yes, you need to update the firmware so the heating function can be activated.


I have seen my 10% min SoC be breached during a rapid discharge, where it hit 8%, after a bit of time it seemed to recover back to 10-11%. Usually recommended that you bottom and top the battery, either monthly or quarterly to allow the BMS to calibrate and track the SoC better.

[Phil M]

Thanks for the reply.

The cold weather explanation sounds exactly how I'd expect it to behave but it has always force charged from 10 to 15, regardless of the weather. Perhaps now it's decided to work properly. We tend to manage to fill and drain most months but I might look at a HA automation to monitor the 100% level and force charge if it hasn't made it to full for a while.

Thanks also for the heads up on the WARM label. I'll check it tomorrow (it's horrible outside now and the battery enclosure is behind a load of junk I need to sort). Having a heater could be useful as, even in the enclosure, it has got close to freezing.

Thanks again!

Phil

[MaterialBarracuda48]

Fox have also been making changes to Firmwares/Back-end configurations that might have adjusted some values.
Several possible things, just have to monitor I guess for a while.