Second ACR adivsed when adding a starting battery?

[BillBerner]

I'm planning on adding a dedicated starting batter to the boat this spring.
Thinking of wiring it directly to the engine on off switch, and using the 1,2, both switch for the 2-4D house batteries.
In that case, will it be good practice to put an ACR between the two house batteries as well between House 1 and the starting battery. Obviously the one downside to this scheme is the inability to use both house and start together to start the engine in an emergency. Might get a Blue Sea switch with emergency both position to replace the single pole on/off that is used for starting battery.
Assuming alternator should come back to one of the house since it is higher amperage than the starting battery.
Thanks.

Bill Berner
#66 Stamford, CT.

[KenKrawford]

Bill, I took a simpler approach. I combined the 2 house batteries (or in my case 4 golf cart batteries) into one bank. For illustration purposes, this is position 2 on the battery switch. My theory was that battery life is directly related to the percent a given battery is discharged. One large bank will generally not be as deeply discharged as a single bank since it has twice as many amp hours. I took the other positive lead and ran it to my starting battery (battery 1). I probably start from this battery once or twice a year and then only to make sure it is able to do its job. By switching to ALL, I can effectively use all 3 (5 in my case) batteries to start the engine if needed. I can also choose which battery to charge via the 1-2-ALL selector switch.
My only expense was a short piece of 2/0 cable to bridge the house batteries to form 1 large bank. I was able to route both the existing positive and negative cables as well as the charger lead to the starting battery under the port settee.
I found that working around the battery switch was very difficult. The cables are very stiff and have little if any slack.
If you go the route you planned, a charging relay would be nice to have.

[BillBerner]

Ken
Thanks for this, and for that matter for everything you do.
So if I'm getting you right, I really just need to parallel my two group 24's for the house, and install the acr between the banks. No need for a second acr and making each group 224 a seperate house bank.
Thanks again

Bill b

[KenKrawford]

If you parallel your (I think you meant 4D's), there is no need for an ACR. If you're charging from the engine, let the battery switch determine which bank you are charging. I use my starting battery only as an emergency backup. Under normal operation, I use the house bank for everything. That way I never change the battery switch. The starting battery gets a trickle charge back at the dock from the battery charger.
Here's a graphic of how my system is wired:

[R.B.]

Some additional food for thought, a great discussion on the batteries and switches:

http://forums.catalina.sailboatowners.c ... p?t=137615

[BillBerner]

Thanks again to both
Coincidentally, I read and saved the post from sailboat owners last night

Bb

[BillBerner]

New discovery today
My boat has 2 battery switches. It appears to be factory installed.
One labeled Main Battery Select, or something to that affect, It is a 4 position off, 1,2, both.
The other is a single pole on off which is switches off power to the engine.
I opened up the panel today assuming I would find both batteries wired to t1 & 2 of the 4 position switch, and the common output going to the engine switch.
WRONG. The batteries outputs were completely isolated. The 4 position only had the "House" bank wired to the #2 position, and the other 4d was wired directly to the engine switch.
I suppose I was either using the both position or the 2 position all the time last season.
The batteries were joined by an ACR so both would still charge from the alternator.
Not a bad way to go, so long as the starting battery doesn't fail.
Deciding if I want to change it when I add the Starting battery. Certainly a no brain req'd system.

BB