Battery Monitor vs Voltage

[sailorboy1]

I installed a battery monitor the other day and charged the battery till the monitor said it was 100% State of Charge (SOC). For reference I have 4 new 6V batteries wired in series/parallel for a total of 460 AH. I charged them the other day till the charge amps dropped to 8 amps and considered that 100%.

At end of my sail today the monitor said I had used 33 AH and that the battery was at 95% charge, which even though doesn't work by math I can accept this.

But the voltage at the time was 12.25V on the monitor and I was drawing 4.7 amps. This voltage is a less than what I would expect for the battery if they really were at 95% SOC.

Should I really believe the SOC on the monitor even though the voltage doesn't seem to match? Is that 4.7 amps enough to effect the voltage vs charge this much?

Has my voltmater been misleading me this much the past couple of years?