Orion DC DC 12v isolated charger can you connect to chassis

[PeterCarole29]

I am Fitting 2x30amp chargers that normally you would connect the in coming negative to the starter battery that in turn is to the chassis
Can I fit the incoming negative to the chassis 6 m away
So run the positive from engine battery to the back of the van into the DC to DC charger and then drop the incoming side negative into the negative on the bus bar load side of the victron BMV-712 smart
If I cant can you explain where the problem will arise
Thanks in advance

 

[autorouter]

Presumably that negative busbar is connected to the chassis locally, and if so that should be fine. There is no need to use the isolated version of the DC-DC charger in a vehicle, because the batteries involved (starter and leisure) both have their negatives connected to the chassis for other reasons. But it's no problem as long as both negatives on the DC-DC charger are connected to a busbar/chassis.

 

[RogerIvy]

If you’re installing an isolated DC-DC into a non-isolated van you can simply run a cable into both negative terminals on the DC-DC. Bear in mind that the negatives of both batteries are connected to the chassis anyway, so the negative terminals of the DC-DC are connected anyway. Pretty much all European vehicles are like this. Boats are a different story, and so are rigs with 24v systems.
What I would say is: make sure your negatives are all connected with decent cables. For example, if the leisure battery is connected to the chassis/EBL using a thin cable it may get pretty hot. If we’re unsure we basically connect the negative of the leisure battery directly to the DC-DC using a 16mm cable and then run a 16mm cable to the chassis.

 

[PeterCarole29]

Presumably that negative busbar is connected to the chassis locally, and if so that should be fine. There is no need to use the isolated version of the DC-DC charger in a vehicle, because the batteries involved (starter and leisure) both have their negatives connected to the chassis for other reasons. But it's no problem as long as both negatives on the DC-DC charger are connected to a busbar/chassis.

All the negatives from everything will go into a bus bar and then to the negative load side of the victron shunt and then other side of shunt goes to chassis cables so yes negative bus bar locally to chassis
Thanks

 

[PeterCarole29]

If you’re installing an isolated DC-DC into a non-isolated van you can simply run a cable into both negative terminals on the DC-DC. Bear in mind that the negatives of both batteries are connected to the chassis anyway, so the negative terminals of the DC-DC are connected anyway. Pretty much all European vehicles are like this. Boats are a different story, and so are rigs with 24v systems.
What I would say is: make sure your negatives are all connected with decent cables. For example, if the leisure battery is connected to the chassis/EBL using a thin cable it may get pretty hot. If we’re unsure we basically connect the negative of the leisure battery directly to the DC-DC using a 16mm cable and then run a 16mm cable to the chassis.

I have a 50mm positive cable from the engine battery to the 2 x 30amp B2Bs splitting to 16mm just under them and 70mm on the liesure batteries also 70mm negative from the shunt to chassis
I can put a larger negative from the engine battery to the chassis to avoid another 50mm x 6m negative cable

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[treblid]

All the negatives from everything will go into a bus bar and then to the negative load side of the victron shunt and then other side of shunt goes to chassis cables

The SmartShunt must only go between the negative of the battery to chassis/ground. The negatives from the B2B chargers go directly to chassis/ground.

Only the battery negative is connected to the BATTERY ONLY connection on the shunt.

 

[autorouter]

As treblid says. The shunt should be close to the battery, the battery negative connects directly to the 'Battery' side of the shunt. Everything else, including the chassis connections, is connected to the 'Load' side of the shunt.

If the leisure battery is actually a bank of two or more batteries in parallel, then the link wires can be between the negatives or directly to the battery side of the shunt. But those are the only other wires permissible on the battery side. The chassis connections go on the load side.

 

[PeterCarole29]

As treblid says. The shunt should be close to the battery, the battery negative connects directly to the 'Battery' side of the shunt. Everything else, including the chassis connections, is connected to the 'Load' side of the shunt.

If the leisure battery is actually a bank of two or more batteries in parallel, then the link wires can be between the negatives or directly to the battery side of the shunt. But those are the only other wires permissible on the battery side. The chassis connections go on the load side.

Thankyou both thankfully it’s not all connected up yet
On a point of equal length of cables when linking the 2 lithiums I assume keep them as short as possible but equal in length