Victron battery monitor shunt install location for sea ray 240

Hello,

I am trying to make sure i pick the right location to install the victron battery monitor shunt on the neg cable. The manual say's to install the shunt before any load. My sea ray 2006 sundancer has two batteries installed in parrellel that feed to a battery selector switch. The batteries have one large negative cable that ties both batteries negatives together and then connects to the Motor, and a second ground off one of the batteries that then runs to a terminal block with lots of grounds on it.

(in photo you can see the one large black cable running from battery to battery then to engine, and a second black wiring that run from battery to terminal block which looks like it has all the load connected to it (second photo)




has anyone hooked up a battery monitor and know which of these location the shut is suppose to be connected to, thanks

What size Shunt?
Typically you want the shunt right off the battery and all load through the shunt. If you don't include the engine, for example, you will loose the alternator charging current on the monitor. Conversely, if the shunt is to the engine's ground and not the house then all of the load and possible the battery charger current will not be seen.
So, I would make up a new battery ground wire and run that to the battery side of the shunt then on the other side of the shunt connect both the engine ground and house ground; this way both are captured. The shunt size needs to be around 350 to 500 amp so the engine start current can pass but also have the granularity to monitor the small loads.

Thanks it's a 500 AMP Shunt.

So basically put the shunt between the batteries and the engine ground and move the house ground to land on the "load" side of the shunt, instead of directly landing on a battery like it does today. (add bad drawing of now and new)