As for the value of separating each battery in a paralleled system and using a conductance tester I have done it on new installations that weren't too large to see how it would play out. As long as your tester can be programmed for the maximum cumulative CCA that the parallel combined batteries are rated at, you can give it a go. My unit is good for a maximum of 3000 CCA. But frankly, I don't recommend this method as the most accurate. Small things like cable connections can make this dicey. These meters are really quite sensitive to any electrical resistance that exists and even a slightly loose battery cable clamp can throw your readings off.