inverter stops charging batteries at 66%

[cyberjagal]

i recently installed a solar system. i have a 8kw growatt inverter (model SPF 8KT HVM) and 4 lithium batteries (48v 100ah).
the system would charge the batteries until full (batteries show full lights) but the inverter shows 66% full and stops charging the batteries at that point. (it shows 66% both on app and inverter screen). when discharging, it discharges from the 66% point and switches off at 20% battery capacity according to the inverter, which is in reality 54% battery capacity. so basically there is 34% of the battery charge that i cannot access. as you can see in the attached pictures, when it hits 66%, only 74w go to the battery and the pv panels only generate enough power to cover the consumption.
i contacted growatt and they were not helpful. i hope someone here would help.

 

[Zwy]

List your settings.

 

[x98myers7]

battery BMS connected to the Growatt? what batteries?

if not... the Growatt SoC logging and reporting is completely incorrect. mine ALWAYS shows 100%. you will need to rely on voltage.

 

[cyberjagal]

battery BMS connected to the Growatt? what batteries?

if not... the Growatt SoC logging and reporting is completely incorrect. mine ALWAYS shows 100%. you will need to rely on voltage.

thank u. i put it on user setting and now the app always shows 100% but the inverter doesnt show percentage anymore, only voltage and amperage in real values. im not well versed in electrics. what are the volages that would reflect different percentages. is there a formula or maybe a general rule of thumb that would help me gauge the remaining charge? thank u again

 

[x98myers7]

https://footprinthero.com/wp-content/uploads/2022/05/LiFePO4-Battery-Voltage-Charts-Image-10.jpg

 

[Steve_S]

 

[cyberjagal]

WOW!!!!
thank you all for all your help!!!

 

[Herb]

The Growatt doesn't have a built in shunt, and can only guesstimate SOC from batteries with communications. I posted several comments in reference to this. This is according to Growatt. The same thing happened to me! My work around is a smart shunt, but you could probably use any shunt gadget that you deem appropriate. I like the smart shunt because is pretty accurate and has an app to go with it. So far this is the only way I use and has worked pretty good. I have 8x100Ah dumb batteries by the way.