Re: battery bank dual charger or triple charger?
I think it all depends on how you use the house batteries. If they are permanently paralleled they will discharge and charge equally, and could be charged as one, but if they are on a battery switch that allows you to run one down without using the other you would need to charge them independently. The reason for that is because the higher voltage of the fully charged battery would trick the charger into thinking the discharged one was also fully charged. I think you would also want to make sure they were identical batteries of the same age.
1979 Santana 30 Tall Rig