I wish to monitor the voltages of both the service bank (3 batteries) and the starter battery (identical to the service batteries), which is an easy task with the proper device (BMVxx2 or SmartShunt). I have a BlueSea relay to make the parallel connection between the service bank and starter battery, and this relay is closed 99% of the time (I force the connection). So, the actual setup can be better interpreted as a bank with 4 identical batteries, with the optionnal capability to isolate one of them (the starter battery). Hence, I think it make sense to monitor the charge/discharge of the whole set of the 4 batteries, i.e., not following the scheme given in the manual, but instead connecting the minus of the starter battery to the same side of the shunt as the minus of the 3-batteries bank. In this condition, you may wonder why monitoring the starter battery voltage: simply because this latter battery is not wired with the same lenghts as the 3 service batteries (there is indeed an unbalance between this battery and the 3 other ones). Am I missing some detrimental issue?
I can not think of a problem, people have put starter current through the shunt without problem but you may not read the peak current but as it is for a short duration it probably does not matter.
Thank you for your answer. At the present time, I have a legacy Mastervolt controller, but for consistency of my setup, I am considering to replace it with a BMV-7xx Battery monitor. One of my concern is that I don’t know the max amp of my Mastervolt shunt. The bow thruster draw a lot of amps (400ish), I avoid to run simultaneously the windlass, but it may happen for short periods of time, and I was thinking to put a 1000A shunt. Standard BMV controls come with a 500A. Do you know if it is possible to replace with a 1000A (with an additional fee), or is it necessary to buy the 1000A at the full price (which is then close to the price of the BMV controller?
It looks like you can buy a 1000A SmartShunt but I have not seen a 1000A BMV either.
My concern is, is there a risk to blow the shunt if more than 500 A is temporary drawn from the batteries, e;g;, 600 A for a few seconds ?
In the old forum there were many posts that the starter current could pass through a 500A shunt without any problems.
https://community.victronenergy.com/questions/121755/bmv-702-shunt-max-short-time-current.html
Thanks for the info. So I will go with the default 500 A shunt: the bow thruster is 7 HP, equivalent to about 5.2 kW, i;e.430 A. (@ 12V),
and the windlass is 1 kW, i.e., about 80 A. The 500 A shunt should hold it. Cheers!