DC Circuit Busbar Link

Nov 15, 2009
29
Hunter 39 New Castle, NH
I'm considering installing my battery monitor shunt immediately adjacent to the main DC negative busbar block. In doing so, my plan would be to use a flat metal type busbar link from the output side of the BMV shunt terminals to one of the terminals on the main DC negative busbar block instead of another battery cable. My plan will require a flat busbar link approximately 3 in long. The shunt is rated for 500 amps. Any thoughts on using this approach? Any recommendations for the size/type/mfg of link to use? A picture below shows the main DC block and proximity of the BMV shunt.
 

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Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
On my B323, I was lucky to have saved an 8-lug buss/terminal block from some years ago. To install the Victron 600, I cut the block to 4 & 4 busses. Filled in the cut in between.
 

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Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Ron,

Can you explain circuit wise what we are looking at in the picture? What happens at the split between the two busbars?
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
The be
I'm considering installing my battery monitor shunt immediately adjacent to the main DC negative busbar block. In doing so, my plan would be to use a flat metal type busbar link from the output side of the BMV shunt terminals to one of the terminals on the main DC negative busbar block instead of another battery cable. My plan will require a flat busbar link approximately 3 in long. The shunt is rated for 500 amps. Any thoughts on using this approach? Any recommendations for the size/type/mfg of link to use? A picture below shows the main DC block and proximity of the BMV shunt.
While you can certainly create a copper jumper, I get OFC copper bar stock from McMaster, the best practice for shunt placement is as close to the house banks nagative terminal as possible. This allows for the easiest way to ensure that no "sneaker wires" bypass the shunt. When you remotely locate a shunt the odds of sneaker wire bypassing the shunt increase. Shunts, for some odd reason, are one of the number one incorrectly wired electrical components I come across on boat..

The BMV shunt has two sides -LOADS & -BATTERY

On board every DC negative wire must be on the -LOADS side of the shunt. This includes:

Start bank neg
Windlass bank neg
Inverter neg
Charger neg
VHF neg
Bilge pump neg
Solar neg
Wind neg
Fridge neg
DC Panel neg
Etc. etc..

This article can help clarify it better.

https://marinehowto.com/installing-a-battery-monitor/
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
Maine Sail said:
Ron, Can you explain circuit wise what we are looking at in the picture? What happens at the split between the two busbars?
Certainly... On the lower left buss bar are the three negs to the batteries. On the lower right bb is anything that makes or uses juice. On the upper right is the Victron shunt, upper left the main neg fuse.

Copper straps connect the "load" buss to the shunt, then shunt to fuse, then the fuse to the battery buss. Nothing - hopefully- happens at the split. "Some day" I'll clean out whatever I used to fill the gap and make it as tall as the lugs. Now that it has been working properly, I'll heat-shrink the lugs/cables.

The "neg" label on the red switch is now a positive switch for the third battery. It just occurred to me if the shunt goes bad or the fuse blows and no spare, and can jumper across the gap in the (originally) 8-lug strip to get home.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Certainly... On the lower left buss bar are the three negs to the batteries. On the lower right bb is anything that makes or uses juice. On the upper right is the Victron shunt, upper left the main neg fuse.

Copper straps connect the "load" buss to the shunt, then shunt to fuse, then the fuse to the battery buss. Nothing - hopefully- happens at the split. "Some day" I'll clean out whatever I used to fill the gap and make it as tall as the lugs. Now that it has been working properly, I'll heat-shrink the lugs/cables.

The "neg" label on the red switch is now a positive switch for the third battery. It just occurred to me if the shunt goes bad or the fuse blows and no spare, and can jumper across the gap in the (originally) 8-lug strip to get home.
It makes sense now. The black shrink wrapped thing in front of the split looked like a bus joining the two at the split, hence my question..
 
Nov 15, 2009
29
Hunter 39 New Castle, NH
Rod, I've found McMaster and their 3350K212 Super-Conductive 101 Copper Rectangular Bar, 1/4" x 1" for my project. I could not find specs. Do you know if this is adequate for a max of 500amps? Also, I read through your BVM article previously when I first installed the BVM a couple years ago and also recently refreshed my memory reading again through some of your other articles. All good stuff and thank you. However, now that I've done some reading and have become dangerous with some knowledge, you've got me wondering if I should also look at rewiring my house bank to more effectively balance the use and charging of my batteries (I've just invested in new AGM's).

So now that I'm wondering, my question is, instead of having the positive terminals on each of the house batteries coming back individually to a common stud with fuses and having each of the negative terminals coming back individually to a common block on the battery side of the BVM shunt, should I rewire them so that the positive terminal from one battery connects to the positive on the second battery and then connects to the house load/charging circuit while the negative from the second battery is wired to the negative of the first battery going in the opposite direction back to the battery side of the BVM shunt?? (note: my house batteries are in different locations so the cable lengths will not change regardless of which connection configuration is used)

I've attached a diagram for my current state of wiring and the possible change I described above. Thoughts?
 

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