Is my BMS Max Charge Current being overly-restricted?

[JimH]

Hi all - equipment as in my signature below. I had an additional ECS2900 slave battery installed on Monday 18th November. All inverter and battery firmware was updated on the same day to the latest versions available.

Despite increasing my Octopus Agile forced charge windows a couple of times (they're now set to force charge at 01:31-03:59 and 13:01-15:59 with Max SoC at 100%) my battery stack hasn't reached 100% SoC without manual intervention (which I did as I was watching it on the night of the 19th) for extra time.

My battery and inverter are in a loft space alongside my gas boiler and it isn't particularly cold in there. Inverter is set to the standard 40A Max Charge and Max Discharge current.

I'm fairly new to this (initial install Feb 2024) but these HA charts seem to suggest that the BMS is overly-restricting my charging rate via BMS MAX Charge Current? This may not be coincidental with the additional battery capacity (more likely firmware-related - it's a G2 inverter which has been through quite a few iterations already) . Th

Is this "as expected" and temperature-related or is there anything that I can change? The reason for the extra battery was to see me through the day/night in winter when there's next to no PV but it's hardly any better than I was before the extra 2.88kWh was added....

Thanks in advance!

[JimH]

By way of update :

ModBus connection reports "BMS1 Temperature" as per the graph above - currently 19.8 degrees C BUT...

Fox ESS app V2 Battery tab shows "Temp" currently at 8.5 degrees C - this isn't exposed in the HA Community Modbus Integration v1.5.9 by TonyM1958 that I'm using (the only one that was updated to work with Gen2 inverters when mine was installed...) - where does this come from and which is most likely used by the BMS to manage charge current??

[tony.matthews1]

What BMS firmware do you have?

We've noted that charge current is more restricted from firmware 1.014: this is case the max charge currrent is restricted to 15A below 20C (lowest cell temperature) and 10A below 15C. This was raised with Fox but I don't know if they have done anything about it yet.

Earlier BMS firmware allowed a higher charge current at these temperatures.

[JimH]

Hi Tony - BMS master firmware was updated to version 2.000 (yes, really 2.000!) when my additional slave battery was updated to 1.13 to match the existing slaves... It does seem overly aggressive. I've just had an error code 195 (charge over current) too when the sun came out and have shut the battery down for 15 minutes to reset....