Battery Isolator with Exciter Wire-gctid393864

[Guest]

Allrighty. I want to hook up an isolator to my boat, like so:



I know. An ACR is better. I learned this after I bought the isolator. I don't care about the small voltage drop. I just run a radio when I'm stopped, and I only stop for a few hours, so I don't care about the efficiency you guys with massive cabin cruisers want.

Anyway. The isolator has an "E" post, a fourth post to accomodate "GM Delcotron CS series alternators that have an excite wire". You're supposed to buy some stupid wiring harness to hook up the isolator in that situation. Now, I don't have anything for that wiring harness to plug into, as I don't have a GM car with a GM wiring harness. I DO have a GM engine, and it has an alternator that has an "EXC" excite terminal, (although it's a DB Electrical generic replacement for a Mando OEM alternator, I think).

Does anyone know if I have to worry about any of this crap? Do I just wire it exactly as you see in the pic above, with the alternator + wire directly to isolator, leave all the other wires, (EXC purple wire and S reddish wire), where they are on the alternator?

The isolator.

Attached files [img]/media/kunena/attachments/vb/697483=29008-MBSS schematic w ACR alternator wiring.jpg[/img]

[Guest]

No one knows? It's an '87 Gm 305 V8, 3 wire alternator. If anyone has an idea, or at least knows if I'll blow something up if I just move the positive wire from the starter assist (pos wire goes from alternator to the starter assist, where it shares a common pole with a wire headed to the starter), to the isolator and leave all the other wires alone, I'd appreciate any advice. I was planning on doing it this weekend.

[2850Bounty]

Shorty, if after having been here since May, 2009, you were still not aware of the isolator -vs- the ACR, then we'll somehow find a way to forgive you, and we'll also cut you some slack for calling this "crap" re; the importance of it!

As per your schematic, this should work for you.

However, your schematic does not show this "E" terminal.

If you plan to use an "E" terminal, can you show us where you intend to connect it?

[Guest]

Jeez Rick, have I been here that long?

Anyway, I actually stole that image, I was too lazy to make my own....in fact, I stole it from one of your posts, from a while back, where you were attempting to convince someone to not buy an isolator, but get an ACR instead. :-).

Anyway, here's what I propose:



My alternator has a "S" terminal that goes to the instrument panel and probably the ignition switch. It has an E terminal that has a wire that just goes and buries itself in the engine....I have no idea what that one does. It has a Pos terminal that currently goes to the starter assist solenoid. I propose moving the pos wire from the starter assist solenoid to the isolator, as shown above.

My question is, do I connect the E terminal on teh alternator to the EXC terminal on the isolator? Or do I just move the pos wire only, and call it a day?

[Guest]

shortyjacobs wrote:
It has an E terminal that has a wire that just goes and buries itself in the engine....I have no idea what that one does. It has a Pos terminal that currently goes to the starter assist solenoid. I propose moving the pos wire from the starter assist solenoid to the isolator, as shown above.

My question is, do I connect the E terminal on teh alternator to the EXC terminal on the isolator? Or do I just move the pos wire only, and call it a day?

Shorty, You mentioned an unknown wire. I have a similar wire identification problem. If you could have a look at my thread with pictures of the unknown orange wire with the white tag. Is your set up similar? Any info of what this wire is or whether its needed or its function would be would be helpful. Thanks, Mike

Heres the link: http://www.baylinerownersclub.org/fo...ernator-wiring

[Guest]

EZ Ours wrote:
Shorty, You mentioned an unknown wire. I have a similar wire identification problem. If you could have a look at my thread with pictures of the unknown orange wire with the white tag. Is your set up similar? Any info of what this wire is or whether its needed or its function would be would be helpful. Thanks, Mike

Heres the link: http://www.baylinerownersclub.org/fo...ernator-wiring

Wish I could help. I'll take a look next time I'm in there....didn't get a chance to do the isolator yet anyway - anyone know where to buy decent wire?? 6 or 8 gauge should do me...

[Guest]

Welp, I went ahead and wired it up. Left all three wires on the alternator. The positive wire coming off the alternator (orange), routed down, around, and over to my starter assist solenoid. I disconnected it there, cut off the ring terminal, and used a butt splice to attach it to some more wire of the same gauge. (Sealed off the connection with heat shrink). Ran that new wire over to the isolator and did the rest as pictured below. Did not touch the purple or red/purple wire on the alternator, did not attach anything to the "E" terminal on the isolator.



Started it up, works great. 14.2 to 14.3 volts at each battery in idle, regardless of the position of my battery switch. It was about 14.7 before, so I lost around 0.5 volts going through the isolator. Que sera, sera.

EZ Ours - no help on your problem, sorry....here's a pic of the back of my alternator: