I can't offer any how to test suggestions
For finding capacity
But this morning after 13 hrs of no charging, down 153 amp hrs from 675
Voltage with 5 amp load showed 12.66, no solar charge it's raining
Capacity showing 77 percent on the meter
I slept on a heating pad 8 hours for my back,, small pad 3 position switch on low
To see what the overnight low voltage under load dropped to, say the down spike when the fridge cycled on,
I would have to go open the compartment and check the numbers on the turnigy watt meter
Not inline with house loads, but is adjacent to the batteries and does record the low voltage
