question

I'm back from vacations and I made new test, same problem ! The victron communicate to Fronius Primo to lower the power when the batteries are full, but if I loose the grid, the fronius continues injecting to the batteries, the multiplus does not regulate anymore ! Very very dangerous !! Please HELP !

Have you configured the ess selecting that the system has a inverter on AC out?

And, have you set up the fronius in mg50 or 60hz? Have you change this value in fronius? Or does it keep configured in your country?

What you should be doing first is properly connect your BMS battery disconnect contactor. You knowingly did not connect a critical safety component in your setup. Yet, you are blaming the software. The only one to blame here is you.

Fix your house-burn-down-risk first and then troubleshoot the rest of your installation. There can be plenty of reasons why batteries are overcharged (eg. faulty hardware).

Fix your hardware first!

Regardless of not properly connecting the battery cutoff, there is a bug in the ESS/DVCC/Venus GX control. I have a small system in my RV with Venus GX (v3.22), MPPT (v1.61), Multiplus (v424), BMV-702 (v3.11). I configured it with ESS system (I know, Victron says not to in RV/boat), however, I wanted some of the advanced charge control features. If I'm not on grid power, and the Multiplus is switched off, the Venus GX turns the MPPT on full power without regard to the charge voltage limit. The MPPT is still under external control. I know under this configuration/condition, the MPPT should be using the Multiplus charge parameters. So I suspect there is a bug when the Multiplus is turned off with sending appropriate charge parameters to the MPPT. Regardless of where charge parameters are/aren't coming from, I feel the Venus GX should make sure the charge voltage and current limits are not exceeded.