More H37C battery wiring.

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Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Yesterday I took the alternator off of the motor to get a good look at the wiring. This project to replace everything with 1/0 cable is driving me crazy(yes, I know, a short trip). The cable between the alternator and starter, about eight inches, is small. Probably it is #8 wire, maybe #6. Why would I pay $35. for five feet of 1/0 cable to go from the 80 amp alternator to the new bus bar? Why wouldn't one of my old #4 cables be more than adequate?

As you can see my bulkhead has no open space for the new battery fuse and bus bar. And the side of icebox or space next to the shunt are simply too hard to work in. So I am going to mount everything on that engine access panel. I'll have to improve and strengthen the latch system to handle the weight. And add 12" to some of my 1/0 cables. I am already over $300. in cable. :cry:
 

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Well the engineer in me would say that the cable only needs to be sized to carry the amps it will see and a 80 amp alternator certianly does not need 1/O cable. If the cable just goes from the alternator to the starter solenoid your assessment is correct. If something else connects to the alternator + terminal then all bets are off as that load could also be caried on the alt to starter cable if the alternator fails for some reason. Example: if the anchor windless positive is connected to the alternator then if you try to run the windlass with the alternator off the current would come from the battery to the starter terminal and then to the alternator.
Also don't forget to make sure your ground return is of sufficient heft to handle you new 80 amp alternator and all the other loads. It probably is as the same ground (probably but not always) is used for the starter which draws upwards of 100 amps.
 
Feb 26, 2004
23,068
Catalina 34 224 Maple Bay, BC, Canada
Ed, not sure why you're going that route. If your AO goes to your house bank, and the output (C post) of your 1-2-B switch goes to your starter, why do you need the connecting wire? That said, if you do go that route, then you don't need that heavy a wire between the two, since it's only for a short duration load. See Figure 2, here: http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101

Ed, I've seen your earlier posts on this subject, but must admit that I haven't been following them closely, so please excuse me if I seem to be gong backwards on ya.:neutral:
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
My fault because I am assuming too much. This is really a continuation of earlier posts. The recommendation from Maine Sail and others is that 1/0 gauge is minimum for my new golf cart batteries. Especially since I am moving them to the bilge over fourteen feet from the bus bar. At the same time I am connecting the alternator directly to the bus bar. And disconnecting it from the starter post. Thus the reason for the question. Here's that "diagram" again. Everthing was to be 1/0 except the combiner jumpers. Now I am thinking that from the bus bar to the starter I just use one of my old #4 cables. And Rich, that is exactly what I am paying per foot.
 

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Feb 26, 2004
23,068
Catalina 34 224 Maple Bay, BC, Canada
Ed, it appears that the wiring you are showing is "simply" (only?) the combiner wiring, and the bus bar is what I would call your PDP (Positive Distribution Post) for your house bank. The alternator output (AO), charger input, combiner connection for your house bank and the connection to the house bank are on that bus bar, while the other side of the combiner connects to your start bank. Is that correct?

That combiner is the same one I have (WM 130A), what Maine Sail would call a Yandina combiner.

That said, the start wire has nothing to do with this PART of your wiring diagram.

Why?

If you are using either a single 1-2-B switch OR if you are using the often seen 1-2-B switch plus a single on/off switch arrangement, (see http://c34.org/bbs/index.php/topic,6604.0.html) the battery switch(es) are being employed as "USE" switches, and the AO goes nowhere near the switch, only to the house bank.

Therefore, the wiring TO the starter only goes from the switch TO the starter, nowhere near the bus bar you are showing as your PDP.

You wrote: The cable between the alternator and starter, about eight inches, is small.

In your new overall scheme (not pictured and I don't have a link to your earlier discussion topic), if I understand it correctly, and this portion of your wiring does NOT show it all, then the connector between the alternator and the starter is DELETED, as discussed in that link, Item 1 under Option 1.

What you are asking is if #4 AWG wire is OK to run between whatever switching scheme you are using to your starter (and should NOT be between your AO and the starter). Since this wire is used for short burst of high power, i.e., to start the engine, then it should be fine. That's the way my boat is wired and it has been working just fine for over 25 years.

http://c34.org/bbs/index.php/topic,4623.msg27335.html#msg27335

Battery outputs to my 1-2-B switch are all #4. Output from my 1-2-B switch TO the starter is the OEM #4 wire FROM the C post of the 1-2-B switch to the starter. My house bank is called #1.

The link also includes a link to Maine Sail's older post on this board about how much amperage starters actually draw.

Does this answer your question?

Stu
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Thanks Stu, but I am not sure we are connecting. Here is another look at it. Ignore the combiner. All the wire in this setup will be 1/0 gauge EXCEPT that red wire. It will go directly to the alternator. I'm just saying the alternator is currently connected to the starter distribution post with #8 wire. Why, then, would I use 1/0 when bypassing the starter? Make sense?

Then as far as the combiner I thought I remembered your other post. And that was the wire should be #6 for the jumpers.
 

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Feb 26, 2004
23,068
Catalina 34 224 Maple Bay, BC, Canada
Got it now. I'm just saying the alternator is currently connected to the starter distribution post with #8 wire. Why, then, would I use 1/0 when bypassing the starter? Make sense?

The power is going FROM the alternator TO this bus bar, right? You are also removing that #8 wire.

The issue is load and distance. Maine Sail in the past has, IIRC, promoted the use of 1/0 for the AO. I did my calcs with a 100A alternator to my PDP and with 3% voltage drop came up with #2 wire, NOT 1/0. The 100A alternator will rarely put that out, even with a depleted house bank, I've seen 60A for a short period of time and then it begins to taper off.

Your boat, your choice, but 1/0 for the AO seems like overkill.

It's the VERY short length of that OLD #8 that lets them get away with it. :) Since it's a goner, no issue.

Separate subject, I know: #4 OUT of the battery bank to the switch since the amp draw on the DC side coming OUT of the banks is rarely more than 10-15A.

I think we're on the same page now.

Combiner wiring: the combiner manual says (minimum) #6 wire for the 130A model. Think of it: all it's doing is sending a small amount of current to the reserve bank. Do you have the combiner manual? I do if you need it. I'm going to my boat now to repack my stuffing box and install a new bilge pump float switch, so it'll be later if you need it. Always somethin', right?
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Battery wiring

So why don't you just use the starter cable to charge the batts?
or
Move the buss bar?

Honestly I have no idea what these pictures are telling me. You say ignore the combiner. OK, I see a buss bar with a cable. Not very enlightening.
Perhaps one of those pencil and paper things with all the components in generally the correct relative position would help?

Putting on my electrician’s hat, you generally get the lowest cost solution when you buy the least amount of wire. This also gives you the lightest and most efficient solution. By efficient I mean you don't waste a lot of energy heating wires in ling runs back and forth from your bats to the controls. Make one long high amp run to the controls and then buss it there. If you have to have a long run from alternator and from the starter then combine the two with a short run between the two and use the larger one to handle the larger load (starter in this case).
It makes no sense to have two long runs when one will do.
 

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Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
The combiner doesn't factor in so far as the new cabling is concerned. All it does with a couple of #6 jumpers is tie the 12v bus to the start battery fuse(bottom right) when the start battery is low.

I'm doing just two things to the original wiring. Replacing all the #4 cable with 1/0 even though Maine Sail and others recommended 2/0. And bypassing the starter distribution post by connecting the alternator directly to the house bank(via the bus). A major reason for the heavier cable is the move of the house batteries to the bilge, a 30' round trip.

What is missing from the picture/diagram is the battery switch. It is a new Blue Sea with 1/0 wiring. Pos. #1 to the start battery fuse, Pos. #2 to the bus bar. Also on the bus bar is the Heart 100 amp charger, the 80 amp Balmar(red #4 cable), and the 15' cable to the house bank. The switch common still goes to the starter distribution post. I have kept all wire lengths to a minimum. Maybe the order to GenuineDealz helps clarify(PDF).

P.S. caught the jumper error, #8 instead of #6. I am placing this order on Monday after more comments and much thought.
 

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Feb 6, 1998
11,711
Canadian Sailcraft 36T Casco Bay, ME
The combiner doesn't factor in so far as the new cabling is concerned. All it does with a couple of #6 jumpers is tie the 12v bus to the start battery fuse(bottom right) when the start battery is low.

I'm doing just two things to the original wiring. Replacing all the #4 cable with 1/0 even though Maine Sail and others recommended 2/0. And bypassing the starter distribution post by connecting the alternator directly to the house bank(via the bus). A major reason for the heavier cable is the move of the house batteries to the bilge, a 30' round trip.

What is missing from the picture/diagram is the battery switch. It is a new Blue Sea with 1/0 wiring. Pos. #1 to the start battery fuse, Pos. #2 to the bus bar. Also on the bus bar is the Heart 100 amp charger, the 80 amp Balmar(red #4 cable), and the 15' cable to the house bank. The switch common still goes to the starter distribution post. I have kept all wire lengths to a minimum. Maybe the order to GenuineDealz helps clarify(PDF).

P.S. caught the jumper error, #8 instead of #6. I am placing this order on Monday after more comments and much thought.
Ed,

1/0 or 2/0 I suggested for the starter and battery cable wiring. I don't know your alt size or run length so can't really comment. If you direct wire the alt size it for the smallest volt drop you can IF you are not sensing the voltage with a dedicated sensing wire.

VD in alternator wires is important. A 3% VD in an alternator wire has the alt putting out 14.4V but the batteries only seeing only 13.9 +/- volts. This will chronically undercharge your bank and slow your absorption charging time.

If you have a regulator that allows you to directly sense the battery terminal then the alt output wire can be smaller as the regulator will compensate for the VD and run the voltage higher so that it sees 14.4V at the battery terminal. If you have an external regulator be sure to take advantage of the voltage sensing wire.

If your regulator is set for 14.4V and you actually want to see 14.4V, or close to it, at the battery terminal, then the wire may need to be large.

On some factory wired systems I can measure 14.4V to 14.6V at the alt and see just 13.8 +/- at the battery..
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Actually this thread does mention that it is an externally regulated 80-amp Balmar. And the PDF above does have all the wire lengths. I could eliminate the question about the alternator directly to the bus. Just leave it alone and trust the new switch to not fry the diodes.
 
Feb 6, 1998
11,711
Canadian Sailcraft 36T Casco Bay, ME
Actually this thread does mention that it is an externally regulated 80-amp Balmar. And the PDF above does have all the wire lengths. I could eliminate the question about the alternator directly to the bus. Just leave it alone and trust the new switch to not fry the diodes.
All I saw was "80 amp alternator" hence the confusion. With an external regulator you'd be best served to wire the alt directly to the house bank AND sense the voltage there with the red regulator wire. You can't sense the house bank and leave the alternator on the 1/2/BOTH.... It's an either/or not a mix...
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Test fit of the new battery cables.

Does that look like $370. worth of cable and assorted? I just hope at $5.40 a foot that I got the lengths right. I am not happy with the Blue Seas battery switch. It does not fit flush on the bulkhead, has legs. Maybe I bought the wrong one. The terminal strip will replace one for the mast wiring.

And here it is all wired to the new panel and ready for the boat. Everything is there but the batteries. And the cable from the charger. The 1/0 cable sure looks excessive. Will the next owner be impressed? Lower right is the fuse for the house batteries that will be fifteen feet away in the bilge. You can see that I kept a #4 wire for the direct alternator connection. The combiner wiring is #6. The Link 2000 shunt with all the new 1/0 ground wiring will be just a foot to the right of this panel. There are covers for everything so there are no exposed voltages. Snow is forecast so it might be 2012 before this sees the boat.
 

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