SmartShunt connection advice

[Andy MacD]

So I’ve got a SmartShunt and no issues connecting to the leisure battery and set up.

Question, is it worth also connecting the cab battery? As I need to remove the front seat I don’t want to leave it just now then wish later I’d done it. If I do connect is it the same gauge cable as for the other battery connectors (excluding the small fused +ve connectors).

Thanks.

 

[AdrianChen]

It just reports the cab battery voltage, mines connected using one of the supplied fused cables.

 

[Andy MacD]

Thanks, it was the -ve cable from cab battery to shunt I was asking about.

 

[Guigsy]

They should already be connected together somewhere and share a common ground. The current in the voltage measurement is tiny, so it should do.

Personally I got the temperature sensor and used the input for that instead.

 

[AdrianChen]

Thanks, it was the -ve cable from cab battery to shunt I was asking about.

Oh OK, Ours is just connected to the leisure battery directly so it measures only the leisure battery current and SOC

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[St3v3]

Thanks, it was the -ve cable from cab battery to shunt I was asking about.

Take it to whatever chassis earth you like.

 

[autorouter]

The usual arrangement on a motorhome is not quite like that diagram. The negative from the starter battery goes to the chassis, and the chassis is connected to the load side of the shunt. This is required for many reasons, for example when the alternator is charging the leisure battery when the engine is running. So it should already be connected, and an extra thin negative wire for the shunt electronics is not required.

 

[Figaro]

May I ask how the smart shunt connects in relation to a Victron 12/12/30 B2B and the EBL 99 ?

 

[tinkertaylor]

A B2B is a charger so it's connected as per the pictures charger lable.

Not sure what's going on with the cab battery ground though on the load side od the shunt.........just leave it connected to the chassis of the van, it serves no purpose being connected to the load side of the shunt and may cause issues pulling current through the shunt to run the engine/starter motor etc if there's no other cables to the chassis.

 

[Lenny HB]

May I ask how the smart shunt connects in relation to a Victron 12/12/30 B2B and the EBL 99 ?

It doesn't it just connects inline with the neg terminal on the leisure battery.

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[Figaro]

It doesn't it just connects inline with the neg terminal on the leisure battery.

Sounds like a simple install then.
Thanks

 

[Guigsy]

You connect it to the negative side of your leisure battery. Then treat the other side of the shunt as if it was the negative terminal of the battery. Everything flows through the shunt. Easy.

There's a little fly lead from an input on the shunt to the battery positive so it can power itself and see voltage.

There's also an optional secondary input. You can use that to monitor the voltage (only) of another battery, or you can plug in a temperature probe.

 

[autorouter]

Not sure what's going on with the cab battery ground though on the load side od the shunt.........just leave it connected to the chassis of the van, it serves no purpose being connected to the load side of the shunt and may cause issues pulling current through the shunt to run the engine/starter motor etc if there's no other cables to the chassis.

There is no connection to the chassis on the battery side of the shunt, so there will be no current running the engine/starter motor going through the shunt.

If there is a chassis connection - and I think there should be - it will be on the load side of the shunt. No current goes through the chassis to the shunt unless there is also a corresponding current on the positive terminal. That's the route taken by the B2B current, or the split charge relay current if that's what is installed.

 

[tinkertaylor]

There is no connection to the chassis on the battery side of the shunt, so there will be no current running the engine/starter motor going through the shunt.

If there is a chassis connection - and I think there should be - it will be on the load side of the shunt. No current goes through the chassis to the shunt unless there is also a corresponding current on the positive terminal. That's the route taken by the B2B current, or the split charge relay current if that's what is installed.

I'm taking the schematic as being complete with all the connections, are you assuming there's other connections not shown?

 

[Raul]

A B2B is a charger so it's connected as per the pictures charger lable.

Not sure what's going on with the cab battery ground though on the load side od the shunt.........just leave it connected to the chassis of the van, it serves no purpose being connected to the load side of the shunt and may cause issues pulling current through the shunt to run the engine/starter motor etc if there's no other cables to the chassis.

Starter battery IS connected to the loads side of the shunt. Either by dedicated cable or to the chassis; as in starter- chassis chassis-shunt (load) .
Starter cant"t pull any current trough the shunt on the load side, because it has s separate positive, so it does not complete a circuit. Unless you put them in parallel.
When b2b is on then they are in parallel and only then the starter pushes (not pulling) current into the leisure trough the shunt. When b2b is working, you will see negative amps going trough the shunt in reverse, into the leisure. If you don't have the starter ground the shunt load, the b2b It will not be seen by the shunt.
Hope this makes sense.

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[autorouter]

I'm taking the schematic as being complete with all the connections, are you assuming there's other connections not shown?

As in post #7, that schematic is not complete. If you want to include any alternator currents for example, the alternator negative is the chassis, so a chassis connection needs to be included somewhere, especially if you are talking about a B2B or a split charge relay.

Usually there is a chassis connection to the starter battery negative, and also a chassis connection to the leisure battery negative. When fitting a shunt, the chassis connection to the leisure battery negative needs to be moved from the battery terminal to the load side of the shunt.

 

[Raul]

I'm taking the schematic as being complete with all the connections, are you assuming there's other connections not shown?

It is shown, it says loads and chargers, b2b is a separate charger

 

[tinkertaylor]

It's well past me to tbh,.not sure why anyone would connect the starter battery to the load side of a shunt, surely it should be connected to the battery side of the shunt and the chassis. If you connect the starter battery to the load side of the shunt and the chassis then when you start the van it will pull parallel curent paths through the chassis connection and the connection through the load side of the shunt, which should also be connected to the chassis.

 

[Raul]

It's well past me to tbh,.not sure why anyone would connect the starter battery to the load side of a shunt, surely it should be connected to the battery side of the shunt and the chassis. If you connect the starter battery to the load side of the shunt and the chassis then when you start the van it will pull parallel curent paths through the chassis connection and the connection through the load side of the shunt, which should also be connected to the chassis.

Read post 15, it will NOT pull any current on start up, the leisure and starter are separate banks, separate positives, and needs to stay that way.

 

[tinkertaylor]

Read post 15, it will NOT pull any current on start up, the leisure and starter are separate banks, separate positives, and needs to stay that way.

OK, I stupidly thought the same current would be pulled through the negative and the positive lines, silly me.

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