Victron Smartshunt wiring question

[ArtieKendall]

I've finally got all my components and I'm getting ready to connect them. I have a question about the Victron Smartshunt.

The manual says to connect the shunt's little power wire directly to the positive terminal of the battery. Is that really necessary? I understand why there can be nothing between the negative terminal of the battery and the shunt; you want every electron to pass through the shunt.

But for the power wire, all it needs is power, and I don't see why it needs to be direct from the battery terminal. It would be more convenient for me to connect it to a busbar on the other side of the class T fuse from the battery. It will still be getting power from the battery unless the class T fuse melts.

Am I missing something?

 

[SamDeleted]

Connecting the little pos to the bus bar is fine it'll just be a little less accurate.


Try it with your multimeter, what is the voltage drop , busbar Vs battery terminal , I doubt it's significant

 

[wattmatters]

It needs to measure the battery's voltage, that's what it is for.

It's up to you whether you think that will be adequately done at the battery positive busbar or the battery terminal. With a good set up it should not matter but if you have voltage drop then your shunt will measure that voltage and not the voltage at the battery terminal.

 

[HarryN]

Victron recommends to do it that way - but I don't.

It is fundamentally unsafe to hook up a small wire to a large battery pack and the ability for it to delivery that many amps into a small wire.

What I do ( for mobile applications ) is run a wire to a breaker ( that meets the amp interrupt rating ) - then to a fuse or fuse block - then to the little tiny wires.

Yes, there is a very tiny offset - but it is very tiny. You really need a good volt meter to even detect it.

 

[ArtieKendall]

Thanks for the responses. I have EG4 LL batteries that show their voltage on an LED screen, plus I'll have only about a foot of 2/0 wire from the battery to the busbar, so I'm not too worried about either voltage drop or voltage accuracy on the shunt. I'll do it the convenient way. Thanks again.

 

[wattmatters]

It is fundamentally unsafe to hook up a small wire to a large battery pack and the ability for it to delivery that many amps into a small wire.

The Victron positive terminal wire has an in-built fuse.

 

[HarryN]

The Victron positive terminal wire has an in-built fuse.

You are right - it does.

I could not get mentally past what it looks like physically though and it would have required my customer to carry another fuse type for the trailer power system vs all of them just running on the same setup and type.

Good point though. Might just be a mental block issue on my side.

 

[cdsolar]

If you are using EG4 LLv2 batteries and a cerbo or Raspberry pi with VenusOS, you can connect the Cerbo/Pi to the CAN Port of the battery and you don't need the shunt. Here is how I did it with a Pi/VenusOS:

EG4 LL BMS to Victron Cerbo

It is just a matter of time before one of those EG4-LL batteries would set someone's house on fire and they will find themselves out of business due to a class action lawsuit. See my post...

diysolarforum.com

If you are using a Cerbo instead of a Pi with VenusOS, then cable type A is what I think you will need for the EG4 llv2 battery:

VE.Can to CAN-bus BMS cables manual [Victron Energy]

www.victronenergy.com