Best 3 Bank Charging Layout

[Dino]

Hi,
I was wondering what is the best configuration for a 3 bank 12V battery system on a twin diesel cruiser.
I currently have an old Newmar 70A 3 Outlet Battery Charger
440ah Domestic bank - mixed battery types/ages and needs to be replaced.
2 x 115ah engine start batteries. One of these feeds the bowthruster.
2 Engine Alternators
4kW Fisher Panda Generator
No solar panels

I am considering replacing the old Newmar with a modern Victron unit. The more research I do it seems the more I don't like the idea of multi outlet chargers. They seem to have fairly crude systems for determining the rate of charge that goes into each battery. They don't appear to have independent sensing so there is a high risk of frying one of the engine batteries that needs very little charge.

I am thinking of going for something like this...
Victron Phoenix Smart IP43 50A Charger for domestic bank.
Victron IP22 15A Charger for Engine Battery that powers bowthruster
Victron IP22 10a for other engine battery
Victron BMV712 to monitor the domestic bank.
Victron Super Cycle Battery AGM 105ah x 3 to replace the domestic bank.
I am not sure how the alternators are charging the existing batteries so I need to review this circuit and start building up a circuit diagram.
Should I have one alternator charging the domestic bank and the second charging the engine batteries using a VSR? This would top up the engine/bowthruster battery first and than combine the other engine battery to charge it. I'm guessing I have some sort of old fashioned split charger.

Has anyone come across a circuit diagram for this type of arrangement?
Is there anything else I should be doing to improve the system?

 

[BartW]

If you do a complete new install I would place a victron Quattro,
such a unit can connect everything you have nicely, and you will have a 230V invertor on top,
The unit has a extra output for charging / topping up a second battery bank, and honestly, I don't understand the need for 3 battery banks, 2 is enough imo (one engine and one house)
If I can find the time, I will look for the diagram you are asking, but have a look at the Victron webside, and look at application / installation sheets on Victron Multiplus or Victron Quattro, ...

just for peace of mind, you could install / keep onboard a small 15A...20A charger, and or connected that to the engine bank, ...
the BMV712 is a good choice.

one alternator charges the house bank, the other the engine bank,

all this is more or less what I have in a 70ft boat AND in a 26ft boat.

 

[kashurst]

Have a look at the Mastervolt Battery Mate 1603G. I have the previous version on my boat. You connect both alternators and your single output battery charger to it at a common connection. Then there are three independent outputs that go to your three battery banks, in my case port side, starboard (house) side and bow thruster. Very simple to set up and seems to work very well.

 

[novanta]

What kind of boat do you have?

 

[Dino]

I have Broom Crown 37 with twin Volvo Penta TAMD40a’s

 

[Dino]

Thanks for the comments. I am considering using a Victron ArgoFET isolator to feed the two engine starting batteries from one alternator. Is this a good option or should I use a VSR to link the two banks?
One engine battery feeds the bowthruster so I could have one engine battery more depleted than the other.