Victron 712 battery monitor question.

[RedsfanUk]

Hi,just a quick one please. Complete novice at boat electrics,I'm installing the victron shunt to my system. The load side I just want to be sure about.

I'm guessing the shunt goes between my batteries and the battery isolator switch?(see photo) 

Thanks for your time

[robtheplod]

The shunt goes on the negative feed from the leisure batteries, not positive, so not the cable that goes to your isolator switch....

Edited April 22, 2022 by robtheplod

[RedsfanUk]

But that cable on the photo is my negative feed from the batteries(they're in parallel) from the battery master switch.  Sorry I'm puzzled 😀

Edited April 22, 2022 by RedsfanUk

[Tony Brooks]

23 minutes ago, RedsfanUk said:

But that cable on the photo is my negative feed from the batteries(they're in parallel) from the battery master switch.  Sorry I'm puzzled 😀

 

So am I. Any chance the you can annotate your photo to show where each cable goes to?

[Sea Dog]

Disregarding the isolation switch thing to avoid confusion...

 

The shunt should be connected in the negative line from your domestic battery such that all the energy in or out of the batteries passes through it. Any negative boat equipment connections should be made to the other side of the shunt (or busbar fed from it, etc.). There should be no other connection on your battery negative than the cable to the shunt. Nothing. No, not the "except for...", no "but what about..." Nothing. Just the one cable from the shunt. I make that point because if any other negative goes to your battery without going through the shunt, it won't be measured and your BMV will lie to you.  

 

Victron's instructions are pretty good, and you should have no difficulty identifying which side of the shunt is the battery end.

 

Hope that helps.

[Tony Brooks]

2 minutes ago, Sea Dog said:

Disregarding the isolation switch thing to avoid confusion...

 

The shunt should be connected in the negative line from your domestic battery such that all the energy in or out of the batteries passes through it. Any negative boat equipment connections should be made to the other side of the shunt (or busbar fed from it, etc.). There should be no other connection on your battery negative than the cable to the shunt. Nothing. No, not the "except for...", no "but what about..." Nothing. Just the one cable from the shunt. I make that point because if any other negative goes to your battery without going through the shunt, it won't be measured and your BMV will lie to you.  

 

Victron's instructions are pretty good, and you should have no difficulty identifying which side of the shunt is the battery end.

 

Hope that helps.

 

Remember this is a negatively switched boat system and he seems to have an extra large negative cable plus a couple of thin wires. I would not like to advise without knowing what those wires are for. I suspect the three terminal on one master switch post go on one end of the shunt and new link lead go between the switch and other shunt terminal but then there are those thin wires. If he gets it wrong then the meter will not know about all the discharges or charge sources.

[nicknorman]

Some boats, for some reason, have the master switch in the negative line.

 

edit: because it means you only need one switch to isolate both domestic and engine batteries. Not someone's best idea, but never mind.

Edited April 22, 2022 by nicknorman

[RedsfanUk]

I don't know if these photo's help. This is how it was all wired up originally....there's a diesel blown air heating system,and 100w solar wired in there. 

[RedsfanUk]

Thanks for all your replies,much appreciated!

[Tony Brooks]

1 hour ago, RedsfanUk said:

 

I don't know if these photo's help. This is how it was all wired up originally....there's a diesel blown air heating system,and 100w solar wired in there. 

 

 

Not much, are you trying save yourself following the cables and annotating the photo so we do it for you?

 

I can't see enough of the wirirng to even have a guess any more than I have done already.

 

It looks as if you have a coolant fed cab heater in there as well.

[ditchcrawler]

2 hours ago, nicknorman said:

Some boats, for some reason, have the master switch in the negative line.

 

edit: because it means you only need one switch to isolate both domestic and engine batteries. Not someone's best idea, but never mind.

Our share boat was wired like that back in 1988 ish I don't think it was uncommon then, one switch, both batteries

[GUMPY]

6 minutes ago, ditchcrawler said:

Our share boat was wired like that back in 1988 ish I don't think it was uncommon then, one switch, both batteries

They were done like this because the CofC / BSS said there had to be a single switch to isolate all the batteries.

[ditchcrawler]

1 hour ago, RedsfanUk said:

Thanks for all your replies, much appreciated!

Watch out for this little bugger tagged on here in the red circle 

 

Where it says engine and domestics is where your isolator is

[Tracy D'arth]

24 minutes ago, ditchcrawler said:

Watch out for this little bugger tagged on here in the red circle 

 

Where it says engine and domestics is where your isolator is

Bundle of white twin cable on the neg post looks to be a temperature sensor thermistor rather than a connection.

Edited April 22, 2022 by Tracy D'arth

[RedsfanUk]

1 hour ago, Tony Brooks said:

 

Not much, are you trying save yourself following the cables and annotating the photo so we do it for you?

 

I can't see enough of the wirirng to even have a guess any more than I have done already.

 

It looks as if you have a coolant fed cab heater in there as well.

Sorry no not at all,I'll be back at boat shortly and will annotate the photo 😊

[ditchcrawler]

2 hours ago, Tracy D'arth said:

Bundle of white twin cable on the neg post looks to be a temperature sensor thermistor rather than a connection.

Quite possibly.

[Sea Dog]

5 hours ago, Tony Brooks said:

 

Remember this is a negatively switched boat system and he seems to have an extra large negative cable plus a couple of thin wires. I would not like to advise without knowing what those wires are for. I suspect the three terminal on one master switch post go on one end of the shunt and new link lead go between the switch and other shunt terminal but then there are those thin wires. If he gets it wrong then the meter will not know about all the discharges or charge sources.

Yes, I see where you're coming from Tony. But the thin wires will still have their uninterupted negative connection, even from the load side of the shunt. So the rule still stands - only one connection to the batteries from one end of the shunt, each and every other negative connection must be on the load end. Otherwise, any circuits with negatives bypassing the shunt will not be measured by the BMV. Wouldn't you agree?

 

[Tony Brooks]

36 minutes ago, Sea Dog said:

Yes, I see where you're coming from Tony. But the thin wires will still have their uninterupted negative connection, even from the load side of the shunt. So the rule still stands - only one connection to the batteries from one end of the shunt, each and every other negative connection must be on the load end. Otherwise, any circuits with negatives bypassing the shunt will not be measured by the BMV. Wouldn't you agree?

 

 

I agree in gemeral but what if one is a Smartguage negatve. If it were it should go direct to battery negative, not the load side of the shunt. I just want to be sure the correct specific advice is given for the OP's boat.

 

I suspect one of those tripple thick cables may be the engine battery negatve an if so I am  far from convinced it would be wise to pass the full starter current through the shunt and also whatever the engine battery takes probably should not be measured by the shunt.

Edited April 22, 2022 by Tony Brooks

[Tracy D'arth]

4 minutes ago, Tony Brooks said:

 

I agree, but what if one is a Smartguage negatve. If it were it should go direct to battery negative, not the load side of the shunt. I just want to be sure the correct specific advice is given for the OP's boat.

The way is for every negative to be on the out side of the shunt, nothing at all onto the battery other than the shunt.   No matter what they are for.

[Tony Brooks]

7 minutes ago, Tracy D'arth said:

The way is for every negative to be on the out side of the shunt, nothing at all onto the battery other than the shunt.   No matter what they are for.

 

OK more thought and accepted. At least that makes the OPs job easier. However I am still not sure what Gibbo's view would be for a Smartguage as he was so insistent the positive should go direct to the battery.

[ditchcrawler]

16 minutes ago, Tony Brooks said:

 

OK more thought and accepted. At least that makes the OPs job easier. However I am still not sure what Gibbo's view would be for a Smartguage as he was so insistent the positive should go direct to the battery.

Well that is easily answered

 

"1. By reference to the diagram below run a cable (1 mm sq minimum) from the battery negative post to the terminal marked GND in the diagram. This cable MUST go to the battery post. NOT to bus bars, isolation switches, fuse panels, current shunts etc."

[Tracy D'arth]

15 hours ago, ditchcrawler said:

Well that is easily answered

 

"1. By reference to the diagram below run a cable (1 mm sq minimum) from the battery negative post to the terminal marked GND in the diagram. This cable MUST go to the battery post. NOT to bus bars, isolation switches, fuse panels, current shunts etc."

I didn't know that.  Never used a smart anything, much too complicated for an old biddy like me.

[BEngo]

23 hours ago, nicknorman said:

Some boats, for some reason, have the master switch in the negative line.

 

edit: because it means you only need one switch to isolate both domestic and engine batteries. Not someone's best idea, but never mind.

Like many stupid things, it was originally mandated by the Boat Safety Scheme,  which, as introduced, required a single switch to turn off all power.  With a separate starter or BT battery there was little option but to put it in a common negative cable.

 

N

[Jen-in-Wellies]

23 hours ago, Sea Dog said:

Just the one cable from the shunt. I make that point because if any other negative goes to your battery without going through the shunt, it won't be measured and your BMV will lie to you even more.  

Fixed that for you. 😀

[Sea Dog]

45 minutes ago, Jen-in-Wellies said:

Fixed that for you. 😀

I'll give you that! Its ok on Amps and Volts, probably even on Ah Used which I tend to use to check the First Lieutenant is not being too extravagant with her evening's wireless allowance...