Can I run 2 smart shunts and connect VE direct

[Jonboothx]

Evening all

Wanting to run 2 smart shunts and connect them together via VE direct, is this possible ?

I’m wanting to run the small loads from my battery via BMS and smart shunt to power house lights / fridge etc and a large load from same battery for inverter as a direct connection via Smartshunt

Can these be set up talk to each other so SoC can be accurate over both circuits ?

Thanks

 

[rmaddy]

Why would you want more than one shunt on a single battery bank? Can you clarify what you think the benefit of two shunts would be?

And am I correct in thinking that you wish to bypass the battery's BMS when hooking up the inverter? That's a very bad idea.

 

[Jonboothx]

Hi Maddy, why is it a bad idea to bypass the BMS ? Planning on using a relay to control the remote port on the inverter so when the BMS shuts off the voltage due to low voltage disconnect, it will switch the inverter off too.

Do you know if I can run 2 shunts from the same battery ?

 

[rmaddy]

You didn't answer either of the first two questions I asked in the first line of my previous post.

A BMS is there to control, monitor, and protect the cells of the battery. Why would you want to avoid using it, especially for a high power item like an inverter?

What would the point of the relay be? If the BMS shuts down the battery due to low voltage then no power will be leaving the battery and everything connected to it will lose power and shutdown. Adding a relay to shutdown the inverter will be needlessly redundant. Of course this assumes you wisely avoid bypassing the BMS when you connect the inverter to the battery.

 

[Jonboothx]

If there is no connection via the BMS then the inverter wouldnt shut down, it will remain on, hence relay coil connected to BMS to shutdown the inverter at low power shutdown stage.

The idea of using the smart shunts would be to give some accuracy to the SoC %

If 2 smart shunt could talk to each other then it might give some idea as to the state of battery

So the config would be

1st connection
Battery - BMS - Smart Shunt - Bus bar - fridge/lights/fans etc

2nd connection
Battery - fuse - Smart shunt - inverter

The reason for avoiding the the BMS and going direct is I’ve just bought a Daly 300 amp and very unimpressed, difficult to use and read

Would like to use overkill BMS I own, to run all low current and direct connection to inverter

I’ve spoke to overkill about running 2 or 3 BMS in parallel to ‘share’ the load and they say it won’t work

 

[rmaddy]

Your whole plan needs to be avoided. You must have a BMS on the battery and all loads must go through it. There's no reason to have more than one shunt. The battery (and its BMS) should connect to bus bars. All of your loads (inverter, DC fuse box, charge controller, etc.) should connect to the bus bars. Between the battery and the bus bars would be the main battery fuse and the shunt.

What is your battery setup including bank voltage and capacity?
What size inverter do you have?

 

[Samsonite801]

Your whole plan needs to be avoided. You must have a BMS on the battery and all loads must go through it. There's no reason to have more than one shunt. The battery (and its BMS) should connect to bus bars. All of your loads (inverter, DC fuse box, charge controller, etc.) should connect to the bus bars. Between the battery and the bus bars would be the main battery fuse and the shunt.

What is your battery setup including bank voltage and capacity?
What size inverter do you have?

Yeah exactly. On my RV setup I have 6 batteries each with their own BMS, all 6 feeding through a single Victron BMV-712 (500a) shunt with bus bars on both sides of it, and it works great. It also gives a single common point for both Victron charge controllers (running in sync mode) to pull voltage, current, and temperature from one reading on the bluetooth network. It doesn't even need VE.Direct connections if using bluetooth...

I think Victron even makes up to a 2000a Smart Shunt for high capacity applications...

 

[740GLE]

If you only have cells for one battery (one BMS) and you can’t supply the peak load you’d like (200a JBD). Time for more cells/battery BMS.