battery isolator

[madmax78]

can anyone explain how to wire battery isolater to a 1992 200hp merc outboard? thx http://www.quickcable.com/details.php?partno=303301

[Riverman]

What are you trying to do, charge a house battery separately? If so, don't use a diode style isolator - they have a voltage drop across them that doesn't allow the battery to be charged fully. Use automatic charging relay like that is made by Blue Sea Systems.

[madmax78]

the second battery is mainly for running my stereo. i had the isolator installed with the stereo, but the installer wasn't sure how to wire it to an outboard. i think it is a diode style, is it that bad to use since it is already installed?

[tj309]

Buy a switch that allows you to use Battery A, Battery B, Both, or neither. Hook the boat up to Batt A and the stereo to Batt B. When you park and float to party switch to Batt B. When the stereo quits switch to Batt A, Start the motor, switch to Batt B and take a cruise to recharge Batt B. Overtons sells just such a switch.

[Liberator*21]

I've used allot of "GUEST" diode style battery isolators and haven't had any issues with them in all the boats I've ever had. I'm sure there are cheap brands out there but if you buy a quality brand name product you'll usually get what you pay for. Mine is set up where the "ALT" runs to the center post of my 3 post isolator, then each battery "POS+" cable goes to the right & left terminal, ground goes from the motor block to the starting battery and then to the stereo battery. These set up will protect your starting battery from any drain from your stereo.

[Riverman]

There is nothing wrong with a diode style isolator except what I mentioned. There is a voltage drop across the isolator, measure it and you will see. Due to the voltage drop the house battery will not charge as well or as quickly. If you want to isolate a house battery, a combining relay is a better option as they have no voltage drop.

A switch works the same as a combiner, except ya gotta think!

[Liberator*21]

Jeff,
I got what your saying, but the "GOTTA THINK" part is a tough one..............LOL

[madmax78]

So I just take the pos lead going to my starting batt and connect it to the alt post on the isolator? I will be using a battery charger to top it up at the end of the day, but I would like to keep it charge as much as possible on the water. I was told it's alot harder on the batt if your always running it down. Thx for all the info guys

[Liberator*21]

Ok, maybe this will make it easier to understand. Here's a sketch of how I did mine. What the sketch doesn't show is that the original "RED" wire was removed from the ALT post that your going to place the new wire on. Mercury makes a kit for this that I bought but I don't remember the part number, it's like #4 gauge wire with a fuseable link already installed. If your interested I can give you a number to call (my Merc parts guy) and he'll be able to ship you one TYD.

Option #1: When you remove the original wire, cut off the ternimal end and shrink wrap the wires end to ensure it doesn't make contact with anything, then Ty-Rap it out of the way.

Option #2: Completely remove the original wire from your wire harness. It's allot of work to remove it and if you ever wanted to go back to OEM again you'd have to run that wire through your harness again.

I'd say do option #1, that way you can always go back to OEM by just replacing the terminal ring you cut off.

[madmax78]

i understand how to do it from an alternator, but not sure how to do it from a stator. i can't come directly from the stator so do i come off of the voltage regulator, if so just one of the or both? or do i come off of the starter solenoid? each voltage reg has 2 red wires going to the solenoid. i have a wiring diagram but i can't figure out how to post it. sorry guys i guess i should have said it is an outboard

[Liberator*21]

The sketch I posted is from an outboard Merc 250 EFI. If your trying to come off your Stator...........then I can't help ya out, sorry.

[Zteven]

That sketch will work in concept for a Stator / Rectifier outboard.

As mentioned, you'll need to 'remove the original wire (connected to the rectifier output), cut off the terminal end and shrink wrap the wire end to ensure it doesn't make contact with anything, then Ty-Rap it out of the way.' Next, install a new wire from the rectifier output leading to the middle pole of the isolator as pictured above.

The rectifier should have two input leads from the stator - usually yellow - do not connect to these as these are A/C. Connect to the single output wire.

[madmax78]

Ok Im following you, but I have 2 rectifiers with 2 red output wires on each one that go to the starting solonoid. Do I reconnect them all?

[Zteven]

hmmm... you've probably got voltage regulators then - not rectifiers. In that case I have a diagram that would be of help, but it is on my other computer. I'll get it up for you tomorrow, but as food for thought...

You may have two options on how to go forward. You could connect both regulator outputs and then go to a isolator, or you could keep the output for each regulator separate and lead one to each battery. Either set-up has pros and cons...

I'll post the diagram tomorrow.

[Zteven]

I think this is the actual diagram for your engine, but if it isn't the concept should be the same.