Connecting a victron 12 2000 80, a victron 30 amp mppt, an victron 12 18 dc to dc and a victron 702

Been down this exact rabbit hole setting up my shepherd's hut system, so this feels relevant.

The key thing with a full Victron ecosystem like this is getting the shunt placement right first — everything else flows from that. The BMV-702 shunt must sit on the negative busbar, as the single point where all negative current passes through. If your DC-DC charger (Orion 12/12-18, I'm assuming) or MPPT have their negatives bypassing the shunt, your SOC readings will be garbage.

My wiring order for a similar setup:

1. Batteries → shunt → negative busbar
2. All loads and charge sources connect to busbars (not direct to battery)
3. MPPT and Orion on the charge side, MultiPlus 12/2000/80 treating its charging function the same way

One thing worth flagging for UK folk — if you're charging from a vehicle alternator via the Orion, make sure you've got the isolated version if the chassis grounds differ. Caught me out on my motorhome previously.

Also, are you running VE.Direct cables to a Cerbo or Color Control? Because without that, you're missing half the benefit of buying all-Victron. The ecosystem really earns its money when everything's talking to each other.

What's the battery bank — lithium or AGM? Changes how you configure the MPPT absorption settings considerably.

@SomersetVanLifer ooh yes the shunt placement thing is something I keep going back and forth on with my narrowboat setup! So just to confirm — the BMV-702 shunt needs to go on the negative terminal of the battery, and literally everything that connects to the negative side goes through it, yes?

What I always get confused about is whether the DC-DC charger counts as a load or a charge source for the purposes of how the 702 reads it. Does it matter which side of the shunt it sits on, or does the 702 just see it as current flowing in either direction regardless?

Also — are all four of these devices talking to each other via VE.Direct, or do you need a Cerbo GX in the mix to get them all on the same page? That bit always bamboozles me.

@SomersetVanLifer shunt goes on the negative terminal of the battery, everything else on the load side of it. That's the only way the 702 sees the full picture.

One thing nobody mentions — if you've got the DC-DC charger in the mix, make sure that's also on the load side otherwise your SOC readings will be all over the place. Caught me out on my static van setup for weeks before I figured it out.

The 2000w inverter will pull serious current at full load, worth checking your cable sizing before anything else tbh. Most people undersize that run and wonder why it's tripping.

@LindaClark90 narrowboat adds the alternator complication too doesn't it, bet that's messing with your readings

@ZFS_OffGrid that's really helpful — so just to confirm I'm understanding this correctly for my narrowboat setup, does everything need to route through that shunt negative? Including the DC-DC charger output, the MPPT negative, and the inverter/charger negative all going to the shunt rather than direct to battery?

I'm also wondering whether the 702 BMV needs any specific configuration once it's all wired correctly — I've seen mention of setting the charged voltage and tail current thresholds to match your battery chemistry but not sure what values people are actually using for lithium vs AGM in practice.

@VivaroProject yes, negative terminal, shunt, then everything else hangs off the load side — get that wrong and your 702 thinks your batteries are magic and never discharge, which is hilarious until you've flattened them completely and your Fogstar cells are weeping.

Done exactly this in my static caravan setup and spent a week convinced I had supernatural batteries before realising my MPPT was wired the wrong side of the shunt and cooking the numbers.