Isolator Install Question

[Chill0987]

I am getting ready to install a 140 amp 2 battery isolator on a 2002 tige 22i and I was wondering where to find the alternator wire for the isolator. Is the alternator wire fused in the positive terminal of the current starter battery? I am assuming if that is the case then I would remove the wire from there, run to the isolator, and re-route back to the starter battery with one of the battery outs on the isolator. I would appreciate it if somebody could let me know the best route of attacking this seemingly simple task. Thanks!

[R&T Babich]

The alternator wire routing probably varies depending on the engine manufacturer. I recently added an isolator on our 5.7 Mercruiser Mag MPI. The large orange alternator wire ran behind the engine and showed up connected to a 90A fuse on the starter high current post. Find that wire and do just like what you said - run that line to the center of the isolator and take an output back to where it originally connected. Make sure you have a high amp fuse in the other battery out line from the isolator.

Or:

I added a 1-2-Both switch with surface mount circuit breakers and made the connections with those on the transom. This eliminated extra connections on the starter post making it easier to change a starter. The switch is handy if one battery dies, you can switch in the other to run everything until you can get a replacement. The switch is also a handy place to run those extra wires that connect to the battery and they will be less likely to corrode.

[Chill0987]

OK, I think I am understanding you here. I should disconnect the wire leading to the starter and take it in the alternator in portion of the isolator. I should then take the B1 out and reconnect it to the starter (where it was originally connected) and then I should take the B2 to the second battery and assure to insert a high amp fuse in between the isolater and the second battery?

Also, I was thinking about taking all of the other wires that are currently on the starter battery and put them on the auxillary battery (heater, bilge, blower, etc.), so that I can have all 12V outputs and associated grounds being supplied from same battery. This would make the only output from battery 1 the starter (which I am also confused which wire it is in the bundle of wires (from original +) since it already has a lead from the isolator). Would you reccomend this re-routing of the onboard wires or would you just leave them as is and just run the amplifiers from the stereo to the second battery? My reasoning behind re-routing everything was to assure that there were no circuitry issues with popping noise and to assure that the starter battery won't be drained by the passive draw of the head unit, intermittent bilging, possible horn use, etc. I really appreciate you taking the time to respond!

[Chill0987]

Is there a way to isolate the stereo switch on the dash from the rest of the components or are all of the dash switches wired into one source charge? The reason I am asking is because I am thinking about just wiring the stereo (head unit) switch from the console to the second battery (along with the amps of course) due to the fact that it will be operating while the boat is off. My resoning is that I would prefer not to have it draining the starting battery even though I know it draws very little amperage. Thanks for the help!

[Chill0987]

I just finished installing the isolator on my 2002 22i (actually a very simple process). The easiest way to complete the install was to find the orange 12v output lead from my alternator (or whatever color yours is). After disconnecting the orange wire, I ran a wire from the 12v output where the orange wire was connected to the isolator alternator input. I then ran a wire from the b1 output on the isolator and spliced it with the original 12v orange wire (this allowed for the original battery (starting) to be charged without tampering with the red bundle at the battery). I then ran a second wire from the isolator b2 to the optima blue top deep cycle. It was a success on the first try! The boat cranked and the wires coming out of the isolator were reading about 13.5V each. I would still reccommend having a deep cycle charger onshore, b/c a full draining of your second battery takes the alternator several hours to recharge if you rely solely on it to recharge the battery. I will post install pictures later. I opted not to use the perko switch, but it is very easy to run if you desire.