dual battery question

cjd3060

Cadet
Joined
Feb 25, 2018
Messages
6
So, I had a second battery installed, as we like to float with the radio on. I had asked for a BlueSea system and did not specify anything beyond that... when I picked up the boat, I realized they installed a Battery Switch with AFD, but no Automatic Charging Relay. When I said something about it, I was told that an ACR really wasn't worth the extra money. So, I left it at that. However, I want to make sure I fully understand what I get vs don't get without the ACR.

The mechanic said that I should run with the switch in 1+2 position and that will charge both batteries. When floating, I should kick the switch over to 2 only and that isolates my starting battery.

So, the only drawback with this set-up is that I must manually use the switch to keep the radio from draining the starting battery? Or, is there more?
 

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alldodge

Moderator
Staff member
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Mar 8, 2009
Messages
40,583
The AFD is a Auto Field Disconnect, which means, you can switch the battery switch with the motor running, that's it. Without a AFD feature, you can damage the ALT while flipping the switch.

So you have to do the work and switch the battery switch for your other bat to be charged. If it was me I would be ticked off. The guy doesn't know what he is talking about and maybe the only good thing is he didn't wire and ACR up. If he did he probably would do it wrong, evn though its pretty simple
 

dingbat

Supreme Mariner
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Nov 20, 2001
Messages
15,417
I get in the boat and I turn the switch to on. I get off the boat and I turn the switch to off.
None of that 1-2-both bull dung

On top of that, my starting battery is automatically isolated. I can never forget to flip the switch and drain the starting battery by mistake.

Spend the $10 extra for a make/break selector switch and eliminate the need for an AFD altogether
 

poconojoe

Lieutenant Commander
Joined
Sep 10, 2010
Messages
1,966
Bummer you didn't get what you wanted.
The way he installed it for you is OK except for the fact that you have to do it all manually and you have to remember to move the switch accordingly.

​With the ACR, it charges whichever battery(s) that need charging automatically.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
15,417
With the ACR, it charges whichever battery(s) that need charging automatically.
In reality, the starting battery takes priority over the house battery.

The house battery is only charged once the starting battery is fully charged
 

JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,525
I think you would be hard pressed to find anyone who has an ACR and doesn't think it's worth the money...

I would find a different mechanic, and get an ACR installed. It will only take one time where you accidentally drain your batteries listening to music and find out you can't start your boat to convince you.
 

sam am I

Commander
Joined
Jun 26, 2013
Messages
2,169
However, to take advantage of what has been suggested above, you'll have to make sure you separate the house loads (radio, house lights, etc) from the engine battery path to assure when the key is off, those extra drawing devices (floating around the lake loads) are only drawing on the house batt............

I'm assuming since you've come from a single batt, your mech simply added a second batt, serialized a the DPST (Off/1/Both/2 switch) inline with you starter w/o any changing over of any loads.
 
Last edited:

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Get an ACR installed as well. Well worth the money. As far as putting house loads on the second battery, some boats are very hard to do that with and you typically have to add a separate fuse panel. A 1/2/Both switch is not the correct switch if you are separating house loads.
 

icwingman

Seaman
Joined
Aug 21, 2017
Messages
61
your switch is not hooked up right, you shoukld have all your option on both batterys including starting, everything works on mine in 1/2/both, when its in both they both charge, i also have a dual battery charger hooked up to them, never had a problem
 

badrano

Petty Officer 1st Class
Joined
Aug 7, 2018
Messages
331
Just a quick side question. Would the bilge blower and pump be considered house side or engine side?
I'm starting to think about putting in a 2nd battery but from what I've seen for wiring on my boat so far is that the bilge is fed from a separate 40A main breaker other than the 50A breaker on the engine.
 

alldodge

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Staff member
Joined
Mar 8, 2009
Messages
40,583
Bilge should come direct from a battery thru a fuse no larger then what is required to protect pump. The bilge and blower normally come from the start bat, but they just need to work when needed
 
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