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Discussion Starter · #1 ·
Anyone had any experience with the Blue Seas battery combiner thing? Since I don't do a huge amount of motoring, I have trouble keeping both the house and start battery topped up (no shore charger). I'm thinking this unit will allow both to charge whilst under way, without overcharging one or the other, and without me having to manually switch between the battery banks.
Add-A-Battery Kit - 120A - Blue Sea Systems
 

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Installed this last year in conjunction with a new hi output alternator from Maine Sail, it's working great. Simple install and can do away with the 1/2/both switch.

In addition you need only wire your alternator output to one bank.. the ACR looks after charging both when appropriate. Quite satisfied with the whole arrangement. These things should be fused as recommended, that does add some cost to the installation but it's the safe way to do it.
 

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I agree with the ACR, great product. The switch isn't a great idea though. It is inflexible, not allowing either bank to be used for starting or house loads. The only way to start if the aux/start battery is dead is to combine the house bank with the dead battery - never a good idea, especially with banks of unequal size. The switch is really designed for small boats with equal size banks - like a 20' fishing boat with a single battery in each bank.

The 1/2/both switch is a lot more flexible as it allows you to use either bank for starting. The ideal is 3 simple on/off switches, one for start, one for house and one to cross loads without leaving a dead battery in the circuit. Below is the Blue Seas version wiring diagram, but easy to create with 3 switches (Blue Seas 6006 or similar).

 

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Brian's right, three switches OR the simple and oft maligned 1-2-B switch.

Here's why:

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries - SailboatOwners.com

Please, read the entire thread.

The BS switch is good for console mobos, not so good for sailboats.
 

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Remember you're a womble
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Discussion Starter · #5 ·
OK. Would the ACR and my existing 1/2/B allow me to start on the start battery, switch to the both setting once started to charge the house and start battery without damaging them, and then switch to the house battery once the motor is off and I am sailing (or tied up somewhere)?
That's really all I want to achieve.
 

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Paul

Yes your 1/2/both switch is a better switch for your boat.

The ACR's purpose though is to eliminate having to change the switch to charge.
All charge sources - alternator, AC charger, solar go to the house bank. No charging goes through the switch.

Switching to both defeats the purpose of the ACR. Not necessary ever.

You could start on the house if you wanted to keep it real simple. But whatever position the switch is in makes no difference as the charge current is not passing through the switch. Both banks are getting a full charge.

You could start on either bank and even switching to off wouldn't do any damage.
 

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Discussion Starter · #7 ·
So the switch position is basically just indicating which battery I am running down?
 

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Yes, that's right. You change the switch from a "charge AND use" switch to just a use switch by moving the AO to the house bank.
 
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For the OP, I would spend the money on a solar maintainer. It doesn't sound like you need anything hard core.

On a related point, I've always stowed away a set of jumper cables in the event I needed to jump one bank to another. If truly desperate, I could always just move the batteries themselves. In this boat, I do have a simple AB switch that energizes the engine starter from either the start battery or the house bank. Very simple solution to a bad start battery. It doesn't, however, have anything to do with how they are charged.
 

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Discussion Starter · #10 ·
I'm not going to start hanging solar panels off the rail, plus of course they rely on the presence of the sun, which is a rare visitor in these parts :)
 
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