Smartshunt aansluiting/connection busbar

Been pondering this one for my van build actually — got two Fogstar Drift 100Ah LiFePO4s running in parallel via busbars and wasn't 100% sure where to drop the Smartshunt in.

From what I've worked out (and had confirmed by a few Victron forum posts), the shunt needs to sit on the negative busbar side, between the battery negative and the rest of the system. So:

• Battery negatives → negative busbar
• Negative busbar → Smartshunt (battery side terminal)
• Smartshunt (system side terminal) → all your loads, inverter, charger negatives etc.

The idea being that everything flows through the shunt so it gets an accurate picture of what's going in and out. If you bolt anything directly to the busbar on the load side and bypass the shunt, your SOC readings go to pot pretty quickly.

The positive side is simpler — just busbar to fuse/isolator to loads as normal.

One thing I did mess up first time round: I had my chassis earth tapped off the wrong side of the shunt and the readings were all over the place. Took me longer than I'd like to admit to figure that one out 😅

Anyone else running parallel batteries with a Smartshunt? Curious whether people are using a proper busbar setup or just lugging everything off the battery terminals directly. Also wondering if the Bluetooth dongle placement causes any issues in a metal van — mine seems fine but it's close to a window.

@Brummie86 classic placement puzzle — took me a good while to figure this out on my motorhome build too.

The golden rule I eventually landed on: the SmartShunt must sit between the negative busbar and the battery negative terminal, so every single amp flowing in or out passes through it. Think of it as the one doorway everything has to walk through.

Where people go wrong is tapping it off partway along the negative chain — the moment you do that, some loads bypass the shunt entirely and your state-of-charge readings become fantasy figures.

With your parallel Fogstars, connect both battery negatives to one side of the busbar, then run a single cable from that busbar through the SmartShunt, and only then onwards to your chassis/loads. Everything counted, nothing missed.

Shunt goes on the negative between battery and everything else — one side sees only battery, other side sees the whole world, simple as. 🔌

@ExBrickie94 has nailed the core principle. Worth adding — with parallel batteries on busbars, make sure the shunt sits between the busbar negative and your common negative distribution point, not between individual cells or batteries. Otherwise you'll only be measuring partial current flow.

On my own van build I've got a similar parallel setup and ran it exactly like this:

• Both battery negatives → negative busbar
• Busbar → Smartshunt → chassis/distribution

The Victron app then sees everything — solar MPPT, inverter draw, DC loads, the lot. Accurate SOC depends on all current passing through that shunt without exception, so double-check no rogue negative cables are bypassing it. Even a single earth strap in the wrong place will throw your readings off completely.

@Brummie86 two Fogstar Drafts in parallel is exactly my setup — just make sure nothing sneaky bypasses that shunt or your SOC reading will be telling you fairy tales all winter. 🔋

Learnt this the hard way on Perseverance (my narrowboat, not the Mars rover — though both involve navigating rocky terrain).

Found out my bilge pump was wired direct to the negative busbar, completely bypassing the shunt. Spent a fortnight convinced my Fogstar cells were some kind of miracle technology because the SOC never dropped.