running entire house using 3 x Victron MP II 48/8000 in 3-phase configuration. Was trying some “'big”’ load testing (like starting 5.5kW 3-phase motor air compressor alond with normal house usage). Unfortunately system is tripping occasionally! And i was not expecting it having three 42 kgs trafo based MultiPlus 8000VA inverters (total 24000VA + overloading capacity)!!!
Batteries are DIY four banks, 16x314Ahcells each, think cables, monster bus bar. Each bank has JKBMS 300A.
Now, to protect my IT (IoT, internet, CCTV) i’m thinking about adding 800VA Victron Phoenics, connected directly to main bus bar. Assumption is as follows: as long as at least one battery bank will remain online Phoenics will provide all necessary power to keep IT system up and running, regardless of main 3 phase power from MP II inverters.
What you think? Is it worth it? UPS is another option, but UPS will have a way shorter battery life (don’t want to buy big expensive one).
During my stress tests the only thing that was tripping was inverters. Batteries (BMS) were ok every single time, indicating Multi Plus II 48/8000 in the bottleneck:/
What type of BMS are you using? Does it communicate with the GX? Loss of, or no communications might work up to the end of charge point then shut the inverters down based on VE. Bus settings. So might BMS settings that alarm incorrectly.
You say at one point the inverters shut down, but then wonder if one bank of batteries has shut down, and maybe another bank would stay online. You need to look really closely at the VRM history and write down the times shut down events happen, assuming your VRM update interval is 1 minute, not the default 15 minutes. What data thread stops, what keeps on logging?
Having an independent inverter on precious IOT services may be a good idea IF it isn’t the battery / BMS shutting down first of course
BMS is JKBMS v19. No comm errors. All the bank reported, all the slaves sharing info with master and master with Cerbo. I could see no issues there. Every time BMSes were healthy, only MP IIs were tripping and recovering by itself after 10-15 seconds.
An inexpensive UPS should get you through your brief overload outages and might be a better and less expensive option than a Phoenix.
Check to make sure your outage is due to inverter overload and not low DC voltage.
A 3-phase motor can have a spike of 5x-8x its operating power so 28 to 44 KW in your case. You have about 48 KW of peak power from your inverters so it could be very close without shedding most of your house loads before compressor starts.
A soft start for the compressor is probably your best option to avoid house power interruptions.
Will analyze logs when i have chance. For compressor - 5.5kW VFD is sitting in the box and waiting for installation. This will solve this particular issue. Will do more stress tests soon and will capture more data this time.
Happen again today, three times. When starting 4kW lathe machine. The system is 3x MP II 48/8000. What is going on? Where was no overload alarm on the MP II panels. Nothing. Just shut down. Alarm log shown only time sync error when devices are restarting…
I did exactly what you are planning to do with a 500W phoenix. It powers my Cable modem, Dedicated Node-red raspberry pi, my P1 monitor RPI, my Pi-hole zero2 ,my Venus devices and my Mesh network AP’s. I didn’t link it to my GX device so it is interpreted by the system as DC-Loads.
Time sync errors are typically a secondary alarm after one or more devices faulted for whatever reason.
Without a soft start your motor can generate a massive spike that can drop the inverters or force the BMS to protect. In these instances it may not be able to log an event (you can check BMS logs, sometimes that helps).
Since it always corresponds to your motor starting, that is the likely cause.
There is no errors on BMSes. Every single time BMSes (4 of them) are fine: no reset, no errors, no issues. Only Victrons are switching off for ca 20 seconds. For whatever reason they’re switching off IT SHOULD BE LOGGED IN EVENT LOG isn’t it?
How can device shut down for any reason without logging an error/event?
If it is cycling 3 times every 30 seconds, then it is an overload.
There are reasons something might not be able to log an event during an unexpected fault. All errors are not necessarily clean.
You could always film the 3 inverters with your phone when you turn on the motor, that should provide some audio and video of what the system is actually doing.
