Salvo,
No, the Trimetric's voltage readout does not go to 2 decimal places; something I have complained about several times on this forum. And I have pointed out there is a huge difference in Ah's between 12.2v and 12.12v on a 430Ah bank, and that the Trimetric rounds up; but then I'm told I don't need to know what my battery voltage is, and that I'm obsessing. I have also pointed out that single decimal place voltage meters are good enough for monitoring charge voltage, but not so good at monitoring battery voltage while in service, because of the peukert effect and the inaccuracy in terms of actual soc; to which I've been told it doesn't matter... just don't let them get below such and such a voltage... again, something I simply cannot do with any one decimal place readout that rounds up, unless I check it constantly.
So, for me, Ah monitoring is the way to go. Is it critical, no, but neither is having a 100% accurate fuel gauge, when one can always guess at how much gas they really have, and just fill up more often than needed. All I know is the Trimetric has been very accurate in regards to Ah usage, when compared to actual open circuit/resting voltages. So I use the Trimetric for monitoring Ah's, as well as charging current and voltage, and I use a handheld volt meter for monitoring resting soc; but this requires that I turn off all loads. I also use the handheld to monitor voltages across batteries, during both charging and while under load, to see if the four batts are sharing both the charge and the load equally.
But in the end, the Ah meter is the most accurate indicator of soc, on the fly, and does not require disconnecting the loads.
In your case, you are familiar with both your daily usage and batts, after so many years, but I think for many folks, an Ah meter can be very helpful in determining ones daily usage throughout the year, as their daily needs change, as well as becoming familiar with their batts and charging system.
