jorbill2or wrote:
Batteries have a wide range of voltages even fully charged with a substantial load will show volts in the mid- low 11’s the only way a volt meter is helpful in battery state is a battery that is “ off line “ resting with no load on for a couple hours.. not practical in a rv that’s in use.
That statement is totally misleading.
Given a similar situation, a set of batteries does NOT show "a wide range of voltages".
After a full charge, with a minimum load they will have a "normal" voltage.
After XX hours of "normal" daily (or nightly) RV use, they will have a "normal" voltage within a fairly narrow range.
A simple voltmeter will also instantly tell you if the present situation is charging, floating or discharging.
And charts are readily available that tell you the approximate SOC based on the lightly loaded voltage.
This is not rocket science and does NOT have to be difficult or expensive. But you can make it both difficult and expensive if you want to. I have better things to do with my time and money. A simple voltmeter serves me quite good.