[C320-list] Various Battery Cable Functions

[Dean Vermeire]

The battery wiring in our 2001 C320 (#847) is different than Jeff's description.  I believe it to be the original, factory wiring.

There are 3 negative (black) and 2 positive (red) cables connected to each of the 2 batteries.  I believe they are configured as follows:

Battery #1
	Negative (black) Cables
		1 cable goes to battery #2
		1 cable goes to the battery charger
		1 cable goes to the engine ground
	Positive (red) Cables
		1 cable goes to the battery selector switch
		1 cable (with inline fuse) goes to the battery charger
Battery #2
	Negative (black) Cables
		1 cable goes to battery #1
		1 cable goes to the windlass ground
		1 cable goes to the DC panel
	Positive (red) Cables
		1 cable goes to the battery selector switch
		1 cable (with inline fuse) goes to the battery charger.

The positive connection to the windlass is downstream of the battery selector switch, through a breaker installed near the selector switch.
The positive connection to the DC panel is also downstream of the battery selector switch, also through a breaker installed near the selector switch.  Makes sense.
The starter's positive connection also comes off the selector switch.  Again, makes sense.

The thing I haven't found yet (since I haven't really looked for it) is the positive connection to the bilge pump breaker.  It would have to be upstream of the selector switch, but it is not connected directly to the battery.  Either there is a bus I am not seeing, or it is on the input connection to the selector switch, I suppose.

Dean Vermeire
S/V Moonstruck II (#847)

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Jeff Hare
Sent: Thursday, June 09, 2016 6:55 AM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Various Battery Cable Functions

Dave,

Q: There are three negative cables and two positive cables to each battery. What is the purpose of the each of these cables?

This is typically how they are wired for MK1 hull models with the Yanmar 3gm engine. 
For older hulls where the batteries are on the port side, this doesn't necessarily apply, (Ask Warren for that info.)

The Black Negative Cables.
1 - Fat Black jumper cable that just connects between the negative terminals
     of the 2 4D batteries.  Provides common ground.
1 - Fat Black cable from the Aft 4D battery goes to the Engine Starter Ground.
1 - ~4awg cable from the forward Negative battery to the Windlass Ground.
1 - ~4awg cable from the aft 4D goes to the DC side of the Electrical panel.
1 - ~4awg cable from (one of the batteries) goes to the Shore Power charger.

The Red Positive Cables.
1 - Fat Red cable from Each 4D goes to the 1-2-Both switch.  From this switch, 
     one Fat red goes to the starter, and a ~4awg goes to the house electrical panel.
1 - ~4awg Red cable from each 4D is fused and goes to the shore power charger.  
      On our boat, these wires were encased in black flex tube.
1 - ~4awg Red cable from the forward 4D goes to the Windlass on/off breaker.
1 - 12awg wire should go directly to the bilge pump switch on the panel.  
      Bilge pump power should always bypass the house power on/off switch.

That should get you going...
-Jeff


-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Dave and Ev
Sent: Wednesday, June 8, 2016 10:53 PM
To: c320-list at lists.catalina320.com
Subject: [C320-list] Various Battery Cable Functions

I have a 1999 model #628. I just installed two brand new SRM-4D, which were replacing ones that were at least four seasons old. The old ones were functional but one battery had a bad cell. I have original factory wiring. There are three negative cables and two positive cables to each battery. What is the purpose of the each of these cables? I believe one of the two larger black cables connects the two battery negatives together and the other black goes to the ground bus, but I don't know the function of the smallest cables. While I had no problems at all for the last three seasons other than the bad cell, after the forward battery cabling was completely connected, I noticed that when I connect the thinner black cable to the battery post on the aft battery it appeared that current was flowing (saw an small arc.) The main battery 1-2-both switch was in the full off position. While I had no issues with the batteries prior, I never saw this when I connected these cables at the start of the season. What is the smaller cables function and should there be anything happening when that smaller cable is connected to the negative battery terminal as it did. I looked a the Catalina manual and electrical diagram and never found a good detail of the original factory wiring for the two batteries. I hesitated to leave that thinner negative cable connected to the negative terminal until I have figured this out. 
I am on a mooring with no shore power connected. I charge with the original alternator on the Yanmar 3GM30F which puts out 13.9 volts at the batteries while charging. No new battery charging equipment added by either me or prior owner. All factory original equipment.  Any comments or thoughts?
Dave Cushman
It TIps #628