Battery Monitor Shunt Wiring Best Practise

[WotEver]

2 minutes ago, Keajre said:

My last BSS survey merely lifted up the deck boards, had a brief 10 second look and passed it all hahaha

Yup, some examiners shouldn’t be allowed to continue examining. 

[Keajre]

1 hour ago, Dr Bob said:

There is another option. Buy cheapies and look after them. It doesn't take too much effort to keep an eye on them so they last longer. Buy double the amount and they need far less attention and the DoD is far less.

True, though on this occasion I rather fancied some beefy 6v tractions  :-) 

[David Mack]

1 hour ago, WotEver said:

Not according to 3.7 of the BSS check list:

”Is the electrical system insulated from the hull?

Check any wiring that can be seen to a suitable device such as a horn, headlamp, or navigation light for the presence of a two‐wire insulated cable.

Electrical systems using the hull as a conductor will not pass this check.”

But that is an advice check, not a requirement in the current BSS procedure, as denoted by the A top right below (unlike 3.7.2 which is a requirement). 

 

The extract from the previous BSS Guide posted earlier makes this clearer. 

[WotEver]

11 minutes ago, David Mack said:

But that is an advice check, not a requirement in the current BSS procedure, as denoted by the A top right below (unlike 3.7.2 which is a requirement).  

Well there you go. I never noticed that. 

It makes sense that it’s only an advisory - corroding your own hull is your business and doesn’t affect anyone else. 

[Keajre]

13 minutes ago, WotEver said:

Well there you go. I never noticed that. 

It makes sense that it’s only an advisory - corroding your own hull is your business and doesn’t affect anyone else. 

Wonder how many molecules of steel I’m loosing each time I sound off the horn, I’ll think twice about using my horn :-D

[WotEver]

12 minutes ago, Keajre said:

Wonder how many molecules of steel I’m loosing each time I sound off the horn, I’ll think twice about using my horn :-D

None of any significance until the feed cable develops a fault. It’ll probably never happen and it’s not the BSS’s remit to care. 

[nicknorman]

1 hour ago, Keajre said:

I stand corrected, I dont mind being wrong

It’s a popular misconception both on here and elsewhere, so you are not alone!

[Keajre]

1 hour ago, nicknorman said:

It’s a popular misconception both on here and elsewhere, so you are not alone!

Happy to be corrected if I am wrong, I’ve already learnt tons from just this thread alone.  Do really appreciate CanalWorld

[smileypete]

On 2/18/2018 at 12:34, smileypete said:

OK I modified the diagram in paint rather than try and describe things in words:

Also I moved the fuses to the battery end.

There are a few other bits and pieces that might be worth a mention, but need to go out now, will try to get back to this later...

One thing that springs to mind (now I've uploaded it ) is there needs to be a fuse in the starter batt charge cable, at the starter batt end. There are some different ways to connect the starter alt to the starter batt, some bypass the isolator if the cable is short and well protected, some add a fuse instead.

OK couple of other bits, for the +ve bus bar and fuses you could use one of these a mega/midi fuse box:

Usually about £25 to £30, would also allow a midi fuse for the feed to the DC panel your boat presumably has.

Also if the combi negative return is moved to the the shunt (non battery end), the negative bus bar will only need to handle the leisure alt, MPPT, and DC panel return, so a lesser rated bus bar would do fine, maybe 100 to 200A depending on size of MPPT and leisure alt.

 

[Richard10002]

21 hours ago, TheBiscuits said:

Or the glass is too big (Too much battery capacity for usage profile) 

Agreed, but whatever the size of the bank, daily, (or every other day), charging to pretty much full seems to be necessary to avoid sulphation, so we are always going to be in the slow charging sector on a regular basis, no matter how big the bank.

Edited February 19, 2018 by Richard10002