Battery Bank and ACR question

[CaptKimble]

I recently replaced my two 4D AGM batteries with 4 wet cell 6 Volt batteries in Series/Parallel to make two separate 12Volt battery bank systems. They are combined thru a standard 1-2-both switch with a separate switch to control the engine alternator/starter connection. I have a smart charger that keeps both of these battery banks charged when on shore power that has the ability for a 3rd battery bank. The engine alternator charges the battery banks when the engine is operating. I would like to add a separate battery for the engine starter using an automatic charging relay. I would then have two house battery banks which I would probably combine into one house bank and one separate engine starter battery. I have studied the wiring diagram that is provided by Blue Sea and I question whether it is possible to use the “add a battery” package deal. I’m concerned that the large difference in size (amp hours) between the two battery banks will cause problems with charging via the alternator thru the ACR. My question therefore is : Is using an ACR to provide for charging the two battery banks the way to go in this situation or do I need to explore other options?

 

[LeslieTroyer]

Read the 1-2-both thread. @Maine Sail has a stated dislike for the add-a-Battery product so I would defer that purchase until you understand its limitations

Mahalo

 

[dlochner]

Is using an ACR to provide for charging the two battery banks the way to go in this situation or do I need to explore other options?

You are very much on the right track. Blue Seas has a couple of ACR options. With a 4 GC bank you'll want the SI -ACR. https://www.bluesea.com/products/7610/SI-ACR_Automatic_Charging_Relay_-_12_24V_DC_120A

Check both the Musings With MaineSail forum here at SBO and the articles on his website MarineHowTo.com for great in depth information.

The short story is that with a larger bank (4 GCs wired as 1 large 400+Ah bank) you will get more usable amp hours and the batteries will last longer. All charging goes directly to the house bank, the start battery is charged via the ACR.

Time spent reading on MarineHowTo.com is time well spent.

 

[Maine Sail]

#1 Wire the GC batteries as one contiguously wired bank.
#2 Wire the alt & charger (with proper fusing) directly to the house bank
#3 Place the ACR between the start bank and house bank.

You do not need the Blue Sea "add a battery kit" just the 7610SI ACR

Spend some time here: 1/2/BOTH Switch Musings

 

[marchem]

Here’s how I’m rewiring our Catalina 310. Based mostly on info from Maine Sail. Pretty similar to what you’re trying to do, I think.

 

[Ward H]

Nice wiring diagram marchem.

 

[CaptKimble]

Thanks to all. I had a feeling I was on the right track. I have read most of the 1-2 both posting from Maine Sail. I'll take some more time to read it more thoroughly since I only want to do it once. I'm a fairly decent Aircraft Avionics and systems tech but a lot of what I do know doesn't necessarily translate to the Marine world.