Installing a 3rd battery, how to wire it?
09-08-2016, 10:30 PM
#1
Platinum Member
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Installing a 3rd battery, how to wire it?
I am installing a 3rd battery on the Sea Ray and I see lots of different ways on installing it. Currently each engine has its own battery and battery switch that is separate from the other engine. . There is a 2 way (off, 1, all, 2) battery switch for each battery BUT the batteries are not connected to each other ( I dont know why). I was also thinking of getting an isolator so the house battery doesn't drain the starting batteries. I have seen isolators and automatic charging relays, but which is better? So here is the setup. Twin engines, currently have two battery switches, and 3 batteries (of which Id like to designate them as 2 starting batteries and 1 house battery)
Last edited by phughes69; 09-08-2016 at 10:32 PM.
09-09-2016, 01:09 AM
#2
Charter Member # 55
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I have the same setup. 2 engines, 2 switches and 3 batteries. I added the 3rd battery(31 deep cycle) for the stereo.
Each of the starting batteries is wired to position #1 on each switch.
The 3rd deep cycle is wired to #2 on both switches.
This gives a variety of options. If I run either switch on ALL, it will charge the starting battery and deep cycle simultaneously.
If I switch both switches to ALL, it will essentially combine/connect all 3 batteries.
So realistically, if I had 2 dead batteries, I should still be able to start both engines no matter which 2 are dead.
Each of the starting batteries is wired to position #1 on each switch.
The 3rd deep cycle is wired to #2 on both switches.
This gives a variety of options. If I run either switch on ALL, it will charge the starting battery and deep cycle simultaneously.
If I switch both switches to ALL, it will essentially combine/connect all 3 batteries.
So realistically, if I had 2 dead batteries, I should still be able to start both engines no matter which 2 are dead.
09-09-2016, 11:59 AM
#4
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With a switch, you really don't need an isolator or relay if you have shore power and a charger with multiple legs. If you don't have shore power or only have a single bank charger you would want an ACR... and a HO alternator if no shore power. An isolator causes a voltage drop so you'll never get a full charge. Better to just use the manual switch.
If you have the room and need house/stereo power that will last all day or longer, two 6v golf cart batteries are a true deep cycle setup. A single 12v "deep cycle" is not much better than a starting battery.
If you have the room and need house/stereo power that will last all day or longer, two 6v golf cart batteries are a true deep cycle setup. A single 12v "deep cycle" is not much better than a starting battery.
09-09-2016, 12:32 PM
#5
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The problem with switches and batteries are people.
To remove people from the equation an ACR is great to have to charge a house battery.
So, you have to be honest with yourself and then decide which way to hook up your batteries.
To remove people from the equation an ACR is great to have to charge a house battery.
So, you have to be honest with yourself and then decide which way to hook up your batteries.
09-09-2016, 06:23 PM
#7
Use an ACR over an isolator. Isolators are diodes and by nature will have a slight voltage loss going thru it. An ACR is a switch, open/close. 12v in, 12v out.
Will you notice any difference between the 2, probably not. But given a choice, I'd do the ACR. Plus isolators are old school
Will you notice any difference between the 2, probably not. But given a choice, I'd do the ACR. Plus isolators are old school
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