question

Hi James Its a bit hard to advise as I dont have a full diagram of your setup nor what model Phoenix you are using etc. but basically using the 123 smart to turn off loads or charge by a BP for each is fine.

I use the Victron VE BMS unit and connect this to the 123smart units load and charge relays. this unit then connects to the inverter via the ve bus and thus turns the inverter off if required. when a LOW battery voltage is detected by the 123 smart

this way you dont need the BP at all for the Inverter load, however if you do have other loads besides the Inverter then one would still be required for them

you have to be careful with the BP as these unit are NOT bi directional ie one for loads and one for charge is ok, you should not use only one BP unit to turn off both charge and loads.

below is a very ruff diagram note the blue and orange charge and load colors may need to be reversed basically the orange goes open then the charge turns off and the blue goes open the load turns off you can also use the VE bms to turn off the BPs as well (this diagram is for a multiplus or quattro. I have not connected this to the Phoenix myself so TEST first.

(NOTE This is NOT a authorised usage of the VE BMS unit by Victron)

This is worth investigating.

The Phoenix ( at least my 5kVA version) is basically a Multiplus without an AC input. It can still charge from AC if it is AC-coupled on its output with a PV inverter. It is also a bi-directional charger, and you can enable the full charger settings in the Veconfig software.

Read up on two-wire BMS control of the Multiplus. I am the other side of the world from my Phoenix right now, but I think the two inputs Aux and Temp are physically available to you on a Phoenix and that full two-signal control is available to you.

Edit: I have just checked that the software assistant is available to you on my Phoenix settings file.

This would be the most elegant solution.

Really appreciate your replies guys, I should have also been a little clearer on my design spec.

My inverter is a 3kva Phoenix smart inverter (not multiplus) and I had intended on using a 100a smart battery protect to switch the incoming power supply to my blue sea 12v distributor.

In the photo that I have included it shows the isolating relay being operated buy simply interrupting a positive battery signal with the bms relays, by simply replacing the isolating relay with the h terminal on the inverter and bp would this work in the same way and eliminating the need to use the ve bus bms?

Many thanks in advance for your time

James.

The following photo shows the only inputs I have on my inverter, the link you've provided shows temp sense and auxiliary inputs, have I missed something? I'm very new to this so I apologise if I'm missing something obvious. Would the previous wiring diagram work with this setup?

Regards

James.