Upgrading from lead acid to Smart Lithium, but not getting DVCC to switch off mppts when i disconnect the bms cable as a safety check (breaking comms should stop chargers (it does switch off my phoenix smart inverter)).
The setup:
VE Bus Bms v2
Smart Lithium 25,6-200ah
Cerbo gx (ve bus bms on ve bus port)
Smartsolar mppt 100-20 (ve direct)
Bluesolar mppt 75-15 (ve direct)
Phoenix inverter smart (ve direct and h port on load disconnect of bms).
Smartshunt (for my lead acids, didn’t remove yet).
Settings
All fw up to date
Dvcc on
Observations
Led of ve bus bms not on, however it does turn off the inverter
Mppts both say not networked and not controlled by bms
Devicelist does not show ve bus bms (not vrm and not in remote console)
I didnt power cycle the mppts yet due to hard to reach, perhaps thats the issue? Will do at nighttime.
is it true that the bms cant forward battery data to gx befause there isnt a multi in my system?
Solutions as suggested by chat:
Buy lynx bm$
What do you guys think, do i miss a simple setting?
Help is very much appreciated as i’m in an offgrid install, relying on power and safety mechanisms.
With the VE.Bus BMS you need a VE.Bus inverter/charger like a MultiPlus, Quattro or an old stile Phoenix inverter with VE.Bus.
Only that way the signals from the BMS are transmitted correctly to the GX device and from there to all the other devices.
The BMS also needs the VE.Bus connection to a inverter/charger to work properly.
So either i need to replace phoenix smart w multi (i’m offgrid, no generator). Other inverters: like inverter smart have canbus but 48v only (i’m on 24v).
Or the old inverter ve bus, however, standby consumption/noise?
Or are there other options? Like lynx bms, or does that need a multi too.
the small bms doesnt let me turn of the mppts (no remote connection), or..?
What is the easiest way to be safe, happy to trade out components.. but has to make some economic sense..
That might give the BMS power to start but I don’t know if the BMS will than send the signals correctly to the GX device for DVCC control or if it still needs a VE.Bus inverter/charger.
Thanks community for tagging along, very much appreciated.
The model is a Phoenix Inverter Smart 24/3000 w ve.direct.
When i disconnect the bms to battery cable, it does switch off the inverter. Thought i read somehwere that the bms cable provides the negative. Assuming no signalling via the negative happening or other functional reason it does need the inverter/charger negative?
Considerations for moving forward:
keep phoenix because it’s less loud and replace ve.bus.bms v2 with Lynx BMS, but $$ (worth the xtra buck for less noise)
Replace phoenix w multiplus-II but sound might become issue as we’re sleeping next to it
Other options on 24v?
Is there another way w current hardware to switch off mppts (without dvcc)?
You either switch the battery connection, using a regular relay or a cyrix (BatteryProtect might work, but it does not like reverse currents, so care must be taken when energizing the system) or by creating your own VE.Direct adapter Tx and Gnd go to the Cerbo while the Rx, Gnd and 5V go to the VE.Direct non-inverting cable
Good morning! Thanks for your suggestion! Question, does that keep my mppts in VRM monitoring and with or wothout dvcc, or does the non inverting cable now become a remote on/off?
I prefer seeing values in vrm.
If they still are visible in vrm, could you perhaps expand a little on what ports of the Cerbo the cables go? So i take apart a ve direct non inverting cable, one side goes into mppt, the other into cerbo ports..
Because They report not seeing the bms in the cerbo menu and but say it’s ‘working’. However, if the cerbo doesnt see the bms, how can dvcc work successfully. I’m assuming mppts and other chargers still aren’t controlled by the bms and are in standalone mode, aka no way to switch them off if battery has errors..
In theory i could test it, but how do i know if its watertight. By removing the bms cable it all should stop, and it does in fact stop the phoenix already (not the mppts: showing stand alone mode). But besides checking a disconnect error, how can i also test any kind of other battery error (temp/disbalance),… i suspect it’s impossible to simulate all potential errorstates correctly: beyond scope of what i could test.. safer to just follow the instructions: get a ve.bus multi .
Concluding in short: there is no solution for ve.direct inverter + smart lithium based systems if you wish to have your small mppt chargers (without remote ports) controlled by bms AND seen in vrm. Correct?
You either switch the battery connection, using a regular relay or a cyrix (BatteryProtect might work, but it does not like reverse currents, so care must be taken when energizing the system)
The solution is to keep everything plugged in. Your initial issue was that the MPPTs keep charging when the BMS-to-Cerbo connection was removed. They are controlled by DVCC while a BMS is connected (although very limited when using a VE.Bus BMS, unlike Can-Bus BMS), but they are not shutdown if there is no BMS communication anymore. Thats either a bug on Victrons end, or intentional. I personally would also expect for DVCC to go to zero max charging current when VE.bus BMS communication was lost, but ive never tried that.
Creating a VE.direct adapter i was expecting it to do both, but now thinking about it again, im not sure anymore. While data can still be sent from the MPPT to the Cerbo by the Tx pin, there wont be any control from the Cerbo to the MPPT anymore, so no DVCC control. There will only be on/off trough the VE.direct remote control cable.
I guess this remote control cable simply pulls the Rx pin to Gnd via a pulldown resistor. So i wonder if it could just be used in parallel to commucating to a Cerbo. I might give that a try in a week or two.
Hello Erik. I had a system a bit like yours. IIRC, I learned that the Cerbo’s USB ports, for VE.Direct networking to the MPPTs, were not equally capable. For my three MPPTs I needed a USB hub, which needed to be connected to a particular USB port on the Cerbo to get power. You might want to look at whether you’re using the right port.
I had the three MPPTs connected with VE.Direct via the hub to one of the Cerbo’s USB ports and the Smart Shunt to another Cerbo USB port, also using VE.Direct. A Multiplus was connected by VE.Bus. DVCC worked perfectly with these. The Smart BMS CL 12/100 and Smart Lithium batteries (and the two Smart Battery Protects) were not included in the Cerbo/DVCC network. They didn’t need to be. The Smart Shunt did all the sensing, plus a temperature sensor on one battery going to the Cerbo. Good system.
Update: got a tip to disconnect the MPPT battery + through a Cyrix-Li Charge, which was my first idea.
Meaning; keeping the MPPTs connected through VE.Direct (for monitoring) and disconnect the MPPTS battery + with the Cyrix through the load disconnect of the VE.Bus BMS v2 port. I keep VRM monitoring of MPPTS (and entire system), but not sure if I get DVCC working properly. Anyway, safety should now be ok.
