Victron BMV-712

[Lightwave395]

As I cautiously progress the electrics and electronics modernisation on my 'new' boat (Dufour 38 Classic) I'm intending to fit a BMV-712 as part of the program to replace the somewhat vague voltage display on the switch panel and see what's going on as regards the charging and usage of the 12V side of things

I'm having hopefully age related temporary brain fade - since asking for confirmation is always better than guessing or assuming - I have 4 X 100ah Gel batteries (which I do think might be overkill for my needs) therefore do I take the 'last' -ve of the 4 batteries as the shunt connection - does it matter ?

In the manual, it shows wiring in a 2nd battery, which appears to sidestep the shunt altogether ?

Any other tips or hints welcome

As an aside, I had a 'old tech' Mobitronic unit on my previous boat - seemed much more straightforward for someone without complex power needs...

 

[PaulRainbow]

As I cautiously progress the electrics and electronics modernisation on my 'new' boat (Dufour 38 Classic) I'm intending to fit a BMV-712 as part of the program to replace the somewhat vague voltage display on the switch panel and see what's going on as regards the charging and usage of the 12V side of things

I'm having hopefully age related temporary brain fade - since asking for confirmation is always better than guessing or assuming - I have 4 X 100ah Gel batteries (which I do think might be overkill for my needs) therefore do I take the 'last' -ve of the 4 batteries as the shunt connection - does it matter ?

In the manual, it shows wiring in a 2nd battery, which appears to sidestep the shunt altogether ?

The 2nd battery shown is the engine battery.

Any other tips or hints welcome

As an aside, I had a 'old tech' Mobitronic unit on my previous boat - seemed much more straightforward for someone without complex power needs...

Batteries and shunt should be wired like this, as you have 4 batteries just imagine the 4th one in the middle. If you don't have the VSR, ignore it.

 

[VicS]

As I cautiously progress the electrics and electronics modernisation on my 'new' boat (Dufour 38 Classic) I'm intending to fit a BMV-712 as part of the program to replace the somewhat vague voltage display on the switch panel and see what's going on as regards the charging and usage of the 12V side of things
I'm having hopefully age related temporary brain fade - since asking for confirmation is always better than guessing or assuming - I have 4 X 100ah Gel batteries (which I do think might be overkill for my needs) therefore do I take the 'last' -ve of the 4 batteries as the shunt connection - does it matter ?

In the manual, it shows wiring in a 2nd battery, which appears to sidestep the shunt altogether ?

Any other tips or hints welcome

As an aside, I had a 'old tech' Mobitronic unit on my previous boat - seemed much more straightforward for someone without complex power needs...

You are right the second battery is not connected via the shunt.
The BMV-712 fully monitors the main battery bank as shown in this diagram from the manual.
All the current to and from this battery bank passes through the shunt.


It will also monitor the volts only of a second battery bank.... typically, as PR states,this will be the engine start battery.

This diagram, also from the manual, shows how this is connected.





With a bank of batteries ( 4 in your case ) It is the recommended practice to connect the positive wiring to the battery at one end of the bank and the negative to the battery at the other end .

Some information about connecting multiple batteries to form a single bank here SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

.

 

[Supertramp]

Just check there isn't anything taken directly off the domestic battery that has a separate return direct to the domestic -ve. If so, reconnect to the shunt.

 

[Frankklose]

In these days, I would use the Victron shunt with Bluetooth. To read the values of the BMV-712 is very difficult. I use of the BV712 only the relay to sound when 20 % is reached otherwise the display is useless because of its readability.

 

[PaulRainbow]

Just check there isn't anything taken directly off the domestic battery that has a separate return direct to the domestic -ve. If so, reconnect to the shunt.

Just follow the schematic in post #2