ProNautic 12-40P, use one or all three outputs?

[sv.antea]

- ProNautic 12•40P question: I have a house bank of three aging 12V TPPLs, nominal 100Ah, but real 85-90 Ah capacity each as measured at 20hr rate. Each has its own on-off switch.
I have installed (but not wired up yet) three 50A breakers, to be able to direct full 40A from the ProNautic 12•40P charger
to any battery for (quarterly?) cycling, while running the house loads on the other two, with help from my 270W solar which stays connected to the "Common"
On advice from ProNautic tech support few years back, I have only connected one of the three charger outputs directly to the shared "Common" of the battery switches. I don't recall what the rationale was.
Now I want to connect each output to one of the three ckt. breakers.
Question: Is that a good idea? And why?

Meanwhile, I have talked to Tech Support briefly and they OK'd my idea of using the three outputs. A discussion is welcome, but I think I am going with the three outputs provided.

[rgleason]

Look at MaineSail's write up. He wired all three outputs to the same destination, I forget the reason.

[ranger58sb]

ProMariner recommended (mandated?) none of the three terminals on their earlier Pro-Tech 4 1240 be unloaded. They recommended (mandated?) using jumpers from unloaded terminals to a loaded terminal.

Don't know that any of that would apply to their newer products.

From your description it sounds like you'd have two active banks at any given time? With exact make-up of the two battery bank varying over time, depending on your switching? With the other one-battery bank held in reserve?

What advantage do you expect, versus using those as a single bank all the time... equalizing from time to time if recommended by the battery manufacturer?

-Chris

[sv.antea]

Thank for both replies, I'll check out the post. But I suspect the reason is, each output, to be isolated, has to go through some kind of diode, so spreading the 40A around should keep those devices cooler and maybe even reduce the voltage drop.
In normal operation (I am living aboard and plugged in) all three battery switches and charger output circuit breakers will be on, maintaining all three batteries. When away from the dock I will still keep keep the batteries tied together with all the battery switches on while there is solar and/or alternator output but, but when neither is available I isolate one of the batteries, in rotation, to keep as a back up. The charger breakers then do not matter, but can be flipped off. My Ah counter is set for estimated capacity of two batteries, so I can monitor what I am using and how is the recharging going the next day. While doing extensive cruising few years ago with only occasional plug in, but lots of motoring, I have actually kept the three batteries together all the time, just keeping an eye on the V-meter. Never had any problem.
The whole idea behind the three breakers and three charger outputs, again, is to be able to pump the full charger output to a single battery for "rejuvenation" as recommended for combatting sulphation, while running the house loads (few Amps) with the other two batteries. Or to allow me to run the house loads from a single battery as a way of measuring the battery's capacity, keeping an eye on the voltage and the Ahs used.

[Zil]

On my ProNautic the three output terminals are common to each other. The advantage could be a separate wire to each battery. But I don't see it and used a bus bar.