question

As far as I know, Multis/Quattros can only start delivering power via AC-out when the battery is connected. The problem is that modern Li-Ion batteries need to be wired to CCGX (via VICTRON CAN A cable) to start comunication and be able to be dis/charged. For that CCGX needs to have power, not always available from modern Li-ion.

My solution was to get power from somewhere else, but this is not always possible.

There is an on button on the battery manager... it will boot the battery system, powering up the DC, long enough to establish coms with the CCGX, assuming the cable is correct.

If you dont establish coms the BYD will go back asleep and drop the DC again,

Long enough is some minutes not seconds.

I just set up a new system, not the same but the same tech, more or less. I have a Multiplus and a 13.8 BYD ut the connections/interactions are the same as far as I know.

AC output isn't your problem, you will ger that when the DC is on and you start the inverter/s

What you need to do is make sure the CCGX is talking to ALL the kit it needs to, so it will configure itsself, and yes it will do that but for a couple of minor tweeks as backstop settings and options.

I could be wrong, as I only have a single inverter, but I think base on protacol docs I looked at the Quatros will operate as a single unit once networked.

The CCGX will se one inverter at 30000 VA and the BYD, which it will use as its SOC instrumentation. The charge voltage and current limits are then dynamically set in the inverter by the BMS in the BYD... For example if the battery is cold the maximum charge current will be reduced. Some/most charger settings will be ignored and the CCGX will report the charger, the one made up of the two inverter chargers, as being in remote mode.

I strongly recomend you read everything and ask about speciffics that you dont have a handle on but start by turning it on, at the BMS and establishing coms to keep it on.

Hope that help and that it is not irrelevent for your BYD variant.