ACR Wiring Revisited (again)

[Wurlitzer1614]

After reading through an incredible amount of information and wiring diagrams here, I was feeling fairly confident adding an ACR and fuses (we had neither). The one thing that has me stumped is the smaller red wire on the starter (+) post that feeds the cockpit engine panel. I haven't seen this one mentioned before. Should this wire get moved over to the alternator post so it is being fed from the house battery instead of the start battery? Thanks!

[Stu Jackson]

Your first diagram is somewhat confusing as a reference source, since it shows an ammeter, not a voltmeter in the cockpit panel.  I know it is not perhaps pertinent to your question.  But that diagram also does not show the purpose of any of those wires.  I suggest you refer to this diagram that shows what each of the wires are supposed to do:
https://c34.org/wiki/index.php?title=Engine_Harness_Upgrade

Red is most likely from the start button, but you can check the continuity of the wire from there to the panel.

[KWKloeber]

[Edit]
Your schematic doesn't show a Neg cable on the Alt.  It should have one.
***

Explain why you think that wire belongs on the house battery?

Although it **could** be put on the house, I'm thinking that you are not aware of what/when the harness feeds where.
Read my Harness 101 here:
https://groups.io/g/Catalina30/wiki/7375

You need to fuse that #5 harness wire (FIRE HAZARD).  When I make up those I use a weather tight ATC fuse holder (below) and a 5/16" LUG, not a crimp terminal. A terminal isn't heavy enough when there's flex and movement of the harness.

Additionally the yel/red "S" wire needs attention re: the fuse and how it's on there.   Strain by the harness could easily pull that S wire off the solenoid.
Read my S wire article here:
https://groups.io/g/Catalina30/wiki/7375


I'm not reviewing your ACR wiring because, well, I don't have one and I'm not fully aware of such wiring.  HOWEVER, why is the ACR shown connected to the starter solenoid, "S" terminal?

[waughoo]

I just added a dedicated start battery with Bluesea RBS for house and start as well as a victron dc to dc charger (another way to accomplish what you are trying to do).  The engine battery is only on when I am actively running the engine.  That red lead that is on the starter feeds power to the engine panel at the cockpit.  It should (in my opinion) be left on the start battery circuit rather than be moved to the house.  As Ken says, make sure to fuse that wire.

[Stu Jackson]

I'm not sure any of us have answered your question yet, perhaps you have. 

I would also note that it appears that a portion of your wiring diagram is missing.  Could you post the entire diagram, seems the right side got cut off.

[waughoo]

Stu,

It is all there if you click on the photo.  In the browser view, it IS indeed cut off, but the whole image is available.

[Wurlitzer1614]

Stu - You are correct- I do have a voltmeter instead of an ammeter. Everything else in the M25XP manual diagram matches what I have except I don't have the orange-red wire between the alternator and starter. Were you able to get the full images to load? If not, I will try posting them again.

KWKloeber - Is the purpose of adding the negative wire to the alternator to add redundancy in case the negative wire to the engine comes loose? The way I envision the ACR working is this: Everything except the starter is powered by the house bank. Charging sources charge the house bank. When the start button is pressed, the Start Isolation (connected to the yellow/red wire) momentarily removes the path between the house bank and start battery so 100% of the starting effort comes from the starting battery. If I leave the smaller red wire on the main starter post (B post?), the cockpit voltmeter would be reading the voltage from the starting battery rather than the alternator/house battery while the batteries are not being combined by the ACR.

Regardless of where that red #5 wire ends up connecting to, I will definitely fuse it!

[Stu Jackson]

Stu - You are correct- I do have a voltmeter instead of an ammeter. Everything else in the M25XP manual diagram matches what I have except I don't have the orange-red wire between the alternator and starter. Were you able to get the full images to load? If not, I will try posting them again.

Yes, I right clicked and saved the image, thx.  Usually the full image will load, or require scrolling, in this case it was all there but no scroll bar and the image was cut off.

The orange red wire thing has been discussed ad nauseum for decades, is part of the ammeter/voltmeter upgrade topic in my earlier link and has been discussed by Maine Sail here (from Electrical Systems 101):
Bypass The Orange/Red Circuit  - Maine Sail's version of the wiring harness crap, but includes a good discussion of the wires at the back of the old OEM alternators
http://www.pbase.com/mainecruising/universal_wiring_harness_upgrade

[KWKloeber]

KWKloeber - Is the purpose of adding the negative wire to the alternator to add redundancy in case the negative wire to the engine comes loose?

READ the Harness 101.  That's why I posted the link.  It addresses grounding the alt.

(It looks like you might have an Alt (yellow?) Neg cable, but can't tell from the close-up pic.)

When the start button is pressed, the Start Isolation (connected to the yellow/red wire) momentarily removes the path between the house bank and start battery so 100% of the starting effort comes from the starting battery.

Ok, I understand that concept.  makes sense!

If I leave the smaller red wire on the main starter post (B post?), the cockpit voltmeter would be reading the voltage from the starting battery rather than the alternator/house battery while the batteries are not being combined by the ACR.

Ok, I'm going to MAKE you understand the harness.  LOL

READ the Harness 101 especially the
https://groups.io/g/Catalina30/wiki/11336#The-harness-has-these-bi-directional-functions

Then ask yourself, "What will power functions #5,6,8,9,10 if I move the red wire?"  Is that what you desire?

And, "What will (or more importantly, won't) happen if my house is dead?"  (hint, #5, #6)

What you hook up to the cockpit VM depends on what's you want to know when you are motoring (the VM isn't ON when the key is off)?   Alternator output voltage?  House bank voltage?  Start battery voltage?
I have my preference but it might not be yours.

If the orange wire (that came back from the ammeter) is still in the harness you can use that wire so that the VM will reads whatever you want to see.  (Or put a toggle switch on the panel and read two different voltage sources.)

[Ron Hill]

Wurl : If you still have an ammeter, I'll guess that you probably have NOT changed out the crappy trailer connectors on that wiring harness!!!  Please look at LogoFreak's post on "Electrical Fire" and believe him!!

Can't say anything else!!    A thought   

[Wurlitzer1614]

KWKloeber-

I re-read the harness page on the C30 site and it makes sense now. I pulled the panel last night and took a good look at how everything is wired. Thankfully, the most critical hazards were already corrected by previous owners. The original wire harness connectors have been replaced by terminal strips and are no longer in service. There is definitely still room for improvement and I will work my way through the list of recommended wiring changes. My wiring matches the diagram here, except I have an extra wire on the key switch 'I' terminal for the fuel pump.
https://www.catalinadirect.com/images/features/Z4644%20Wiring%20Diagram.pdf

The yellow wire pictured is a jumper from the AO to alternator sense.

I hadn't considered what would happen if my house bank ended up being completely run down. It's true that I would lose fuel pump, glow, starting solenoid, etc.

Assuming the panel feed is left on the start battery and the AO goes to the house battery, will there be issues with the alternator excite or AC output to the tach? Or are those all electrically isolated within the alternator? If those are isolated, then maybe this is a non-issue. I'd see my starting battery voltage (when not combined) rather than monitoring the alternator, but maybe that's okay with me.

Thanks again to all of you for walking through this with me.

[Ron Hill]

Wurl : If your ammeter is working? You may not realize it, but ALL of your alternator output is going up to your ammeter in the engine instrument panel and then all the way back down to the batteries.  Look at that distance!!!  Your PO has NOT done you any favors!!

You need to do a bunch of rewiring!!  Look in WiKi and the Mainsheet tech notes and there are multiple articles on how to rewire after you remove the trailer connectors !!   

A few thoughts

[Wurlitzer1614]

Ron, if my boat had ever had an ammeter, it's long gone!

[KWKloeber]

Wurl

GREAT as Stu says we need to understand what our wiring does -- then messing with it becomes less of a mystery!!

My wiring matches the diagram here, except I have an extra wire on the key switch 'I' terminal for the fuel pump.
https://www.catalinadirect.com/images/features/Z4644%20Wiring%20Diagram.pdf

The yellow wire pictured is a jumper from the AO to alternator sense.

What most do not understand is that there are two sets of wiring -- the engine harness wiring that Universal installed (gummy bear plug at the engine end.) and Catalina boat wiring (the fuel pump power, the fuel tank sender, and the Alt AC wire to the tach -- all to the panel -- plus the tank negative/bond wire, deck fuel fill bond wire, and battery cables to the engine.)  Universal had nothing to do with those CTY wires going to the panel so they never went thru the harness gummy bear plugs!!  When CTY installed the harness extension to the cockpit panel it simply included "it's wiring" with the "engine wiring" as one bundle.
If you want a no-charge fuse set up for the panel feed wire I have about 50 here. 

The fuel pump wire is redundant!!  When I make a new harness for a customer I run ONE wire and split it at the engine end (to the pump and the Alt excite terminal.)

The terminal strips can be problematic -- it's best that you butt crimp the wires ad do away with the terminal strips.  Per ABYC, every terminal MUST HAVE its wire supported within 6" of the terminal.  That doesn't mean hanging in space with a spare wire wrapped around it as the Seaward "upgrade" instructs owners to do!!!

if your Alt has an external sense terminal could it be use to sense house battery voltage instead of AO voltage?
Yours must be a Motorola 8EM2017KA alternator.

Assuming the panel feed is left on the start battery and the AO goes to the house battery, will there be issues with the alternator excite or AC output to the tach?

I'd see my starting battery voltage (when not combined) rather than monitoring the alternator, but maybe that's okay with me.

No problem - so long as the excite terminal sees 12v, the alt excites.  Same with the tach signal -- they both are referenced to your bonded-together negative battery terminals.

There's an argument that the most important V reading is what you have to start the engine.  Of course I STILL maintain that a start battery should be an **EMERGENCY** battery and used only then but it's difficult to convince folks of that.  With an ACR it doesn't matter much though.  But the V meter in the cockpit is really to show whether the alternator is charging, not meant to give you an accurate battery V (hence why the OEM panel had an ammeter.)  Just put a toggle switch on the panel and you can read either voltage source (or pull the voltage right off the AO terminal to show whether the Alt is charging, regardless of which battery.

[Ron Hill]

Wurl : The only reason that I mentioned an ammeter is because YOU sent a Catalina wiring diagram that shows an ammeter (top post)!!!  I know that some 1988 C34s did come with a ammeter - a hold over from the 1987 C34 production!!

Then even if you have a voltmeter, but all of the "Wiring Harness Upgrade" wasn't done? - the charging from the alternator still took that devious route for current to get to the batteries!!

A thought