BMS vs Shunt Accuracy

I have read numerous posts on how the BMS is not super accurate at calculating the SOC, especially in cases where the batteries are not fully charged every so often.

I currently run on my batteries 100% of the time and let the solar recharge the batteries. If there is not enough solar energy, the grid will charge up the batteries by 30%, so hopefully, the next day, the solar energy can pick up. I'm adding two more solar panels, but it will likely still not be enough to charge the batteries to 100% each day fully.

So the way I use my batteries, it is likely they will not see 100% SOC for a while. This has already caused my BMS to show 44% and my Victron Lynx Shunt is showing 53%

Should I change my Cerbox GX to use the Lynx Shunt as the battery monitor instead of my EG4 LL-S BMS? I have attached the current status from VRM.

Yes, the Lynx shunt will be more reliable, some of these battery BMS units don't seem to catch very low idle loads so they can definitely get out of whack compared to a Victron shunt.

My BMV and Batrium shunts drift over time. Neither account for capacity lost due to balance current, which can be significant from time to time.

Since they're NCM cells, I simply reset to both to 75% when I hit my 3.92V/cell float. I reset them about a week ago:

I have 6 EG4 LifePower4 batteries. I have used my 0-60 VDC variable bench power supply to charge an individual battery while at the same time monitoring the battery/BMS with the BMS_Test software. Anytime charge current drops below 0.5 amps the BMS reports 0 current.
In other words any current less than 0.5 amps is not recorded or managed by the BMS and therefore is not being used to more accurately calculate SOC

The number of batteries in your battery bank will affect this. More batteries means less current per battery. With 6 batteries, assuming 52 volts for the bank; 52 * (6 * 0.5) = 156 watts. Most inverters draw much less than this when idle.
If I have 12 batteries in the bank then; 52 * (12 * 0.5) = 312 watts. The system would have to draw more than 312 watts for the BMS in each battery to measure current and then accurately adjust SOC assuming all batteries are discharging at least 0.5 amps

The above is a rough explanation and is by no means completely accurate, other than my observations when charging a single battery.

My Midnite solar Whizbang jr smart shut is advertised accurate to +/- .25%, and so far it has been so much more accurate than the jkbms. JK will show zero and shunt shows 25% remaining. I’ve ran it down to 10% and JK showed zero for a while. So I would lean on a good / smart shunt over BMS.

I also have a Victron 500A shunt installed and do see a sometimes significant difference in current. At idle my inverter using the IPower software indicates -2.3 amps which is close to the Victron shut while the BMS_Test software shows zero current from each of the 6 batteries

I switched the Cerbo to use the Victron Shunt. I will periodically try to bring the batteries up to 100% so I can reset the SOC on things.