Battery Isolator Installation, Need Help

[Dinows]

I purchased a twin engine isolator without directions, I know that the three terminals on the bottom go to the three battery banks, but which wire do I disconnect from the alternators to run to the terminals on the isolator ? I have 1987 Merc. 350s in a Sea Ray Amberjack<br /> <br /> Thanks Dino

 

[Boatin Bob]

Re: Battery Isolator Installation, Need Help

Not sure if this will help as I have OMC's but recently put Isolators in. My Alternators have a heavy (10 ga) orange output wire coming off the alt that went to my slave starting solenoid which also where the main wire from the battery ties in. I just took that orange wire off the slave solenoid and put it on the input term of the isolator and then ran a 10 ga wire from one of the output term off the isolator back to the solenoid, now my starting battery charges off the alt plus a couple of others.

 

[Dinows]

Re: Battery Isolator Installation, Need Help

Hey thanks Bob, unfortunately for me my Merc is different, my battery wire does no go to the slave, I am sure someone here has the same set up as me

 

[Trent]

Re: Battery Isolator Installation, Need Help

Which make and model isolator did you buy?

 

[Dinows]

Re: Battery Isolator Installation, Need Help

Hi Trent, the isolator is made by Professional Mariner and the model is 2-70-3 Can you help ?

 

[Boatist]

Re: Battery Isolator Installation, Need Help

Dinows<br />I agree with Bob. Sounds like your isolator is for 3 battery banks, is that right??<br />Your alternator will have one Large wire 10 ga or 8 ga and this wire will be bolted on not a push on connector. This is the alternator output wire. You can trace it and see where it goes but it will end up going to the + Positive of your starting battery. Most I have seen connect to the same terminal as your starting battery + Positive cable, which is usually on the starter solenoid.<br /><br />Before you start wireing pull the - Negitive wire off of your batteries for safty but do not forget to put back on clean and tight when done.<br /><br />To wire in your isolator take that Alternator output wire off the starter solenoid and move to the isolator input or alternator post. Next with the same size wire take first battery output and wire to same post that you removed the alternator wire from. With another wire the same size wire from the second battery output to the + positive cable for your second battery. Your second battery must have the - negitive post connect to your engine block again with the same size or larger wire. Use top quality marine wire and good connectors as a poor connection can blow your alternator.

 

[Dinows]

Re: Battery Isolator Installation, Need Help

Thanks, I think I got the hang of it, now how about this. It is just about impossible to get to my starters. Could I snip the wire at the alternator and tie it off then run a new wire from the alternator to the isolator ?

 

[Boatin Bob]

Re: Battery Isolator Installation, Need Help

You could do that but not only do you need to run a new wire from the alternator to the isolator input but you also need to run a wire from the isolator output back to and attach to the wire you just snipped. Are you sure that the alternator output wire runs all the way down to your starter? I would think there would be some kind of solenoid where it attaches unfortunately I don't have any Mercruiser wiring diagrams to refer to.

 

[oldboat1]

Re: Battery Isolator Installation, Need Help

For a two battery isolator (single alternator), the large output wire from the alternator is disconnected from the alternator terminal and connected to the number one terminal on the isolator. A new wire is then connected between the alternator output terminal and the main post of the isolator ("A" on my model). Think of the main post as the incoming charge, and the other two posts as output. The #2 post of the isolator is wired to the positive post of the house battery. Both the house and starting battery are grounded to the engine (common ground).<br /><br />The isolator should be mounted reasonably close to the alternator (but not on the engine).<br /><br />Your isolator hookup should follow the same concept, albeit with the complexity of an additional alternator and additional battery banks.

 

[oldboat1]

Re: Battery Isolator Installation, Need Help

By the way, are you sure you don't have a three-bank isolator with a single alternator? If there is one main post on the isolator (along with the three output posts you describe), it would be intended for one alternator and three battery banks. This wouldn't be a disaster, as you would be charging the house batteries (2) off only one of the engines -- which should be fine. If you use the boat for fishing, I would pick the engine I use for trolling.<br /><br />No single battery should have multiple charging sources operating at the same time. I guess I'm a little curious about your setup. How many house batteries are you using?

 

[Dinows]

Re: Battery Isolator Installation, Need Help

I HAVE A BANK OF 3 HOUSE BATTERIES AND A SEPARATE STARTING BATTERY FOR EACH OF THE TWO ENGINES, THUS THE REASON FOR THE 3 OUTPUTS ON THE ISOLATOR AND 2 INPUTS

 

[Boatin Bob]

Re: Battery Isolator Installation, Need Help

Hey Dinows....no need to shout, everyone is just trying to offer their help/experience. I just did something very similar but I used 2 x 1 input/3output isolators. I have 6 batteries, 2 for starting, 2 for house and 2 for my inverter. I just wired it so each isolator charged a starter, a house and an inverter battery. Plus I carry a set of heavy duty 18' jumper cables so I can boost myself if needed.

 

[Dinows]

Re: Battery Isolator Installation, Need Help

Hey Thanks, I wasnt shouting, The old lady used the computer just berofe I got on and I was to lazy to hit the <br /><br /> Hey thanks for the info. I wasnt trying to shout, the old lady was on the computer before me and I was to lazy to hit the "caps lock button" to bring it back to regular text !!!!!!<br /><br /> Thanks Dino