I am trying to understand how modern 3-stage marine/RV lead-acid battery charge systems work. It's very common to wire a charger in parallel with both the battery bank and the "house" power. This means that when plugged in, the charger is both charging up the batteries and powering any DC electronics.
My understanding of IUoU Charging is that during the "Uo" phase the charger puts out constant voltage until the current draw drops below a given threshold. If the house electronics are drawing from the charger, then how could the charger possibly know what that threshold is? Shouldn't it be quite common for the charger to never hit that threshold and constantly overcharge the batteries (e.g. if the house refrigerator is in the circuit)?