Hello,
I'd like to set up the ESS Assistant for my battery pack (3x 44V 12S Li-Ion), but I run into problems with the Cutoff-Restart Voltage. I.e. cutoff is set to 36V where the BMS will also stop discharging, and resumes when voltage rises above 37,8V, but the ESS Assistant wants this to be at least 43,8V and does not budge here.
Is there a way to adjust the ESS Assistant's voltage expectations?
Is the ESS Assistant even necessary when there's a controlling BMS (serialbattery) ?
Thanks!
To close this: Indeed the "Shutdown SOC" Setting is honored. I set it to 20% and this has been working wonderfully for the last 2 months.
ESS assistant is necessary if you are mixing grid and solar together and want to be able to control depth of discharge. The dynamic cut offs are needed. You could set them all down to the low cut off of the inverter and leave it like that. The BMS will do the rest.
Do you have your low cut off and restart set on the inverting page?
You could switch to an AC ignore to prioritise solar.
There is also a way to use the generator control on the GX to manipulate AC connection. It does depend on how you want to use the system.
Hello,
@Alexandra
My main problem is the IMO too high Cutoff-Restart voltage the ESS Assistant expects, I want it to be lower, otherwise I have to basically charge the battery from empty to 70% before it resumes discharging it again. Unfortunately the pre-set templates are only for LiFePo4 cells, while I do have a Li-Ion.
ESS raises the minimum slightly from the published specs of the Multi. It is in the docs and is a hard limit. You have gone a bit off piste with your design specs.
All but this one detail can be adjusted to suit my battery, it works really well.
Does the ESS Assistant honor the "Shutdown SOC" settings in VEConfig? Because that would work for me as well.
It looks like I just need to let the BMS stop discharging the battery when its just above 38,0V...
Hello @mlau,
I have the same problem, my battery is 12s5p configuration with li-ion cells and using jk bms to communicate with Victron OS and managed battery.I try to start my multiplus 2 inverter but it’s show low voltage and didn’t start. I try to set settings with VE.Configure on inverter settings - DC input low shut-down 37,6 and can’t set DC low restart to good value. Can you tell me all the settings you use to setup Multiplus 2 and why it doesn't start at 45v battery (65% SoC) ?
Thanks in advance
Hi @kokoev,
in veconfigure3 in either the "Charger" or "inverter" Tab, there's a section that's (i think) called "SoC limitation", I set it to 20%, as this is comfortably above the minimum required by the multi to operate. In the ESS Assistant I set the shut-off and resume voltages to the lowest values allowed.
WIth these settings, the battery won't be discharged below 20% (that SOC reading ist provided by dbus-serialbattery based on the bms value), and the normal charge-discharge cycles work quite well now (charge current it limited to 0A again by dbus-serialbattery when SOC reaches 100%).
The "low battery" light does blink until soc reaches about 45% (~44V), but it has no impact on normal operations.
Hi @mlau,
Thanks for the quick reply. I'm interested in what kind of bms you use and how many volts your battery was at when the inverter started working, because in my case it was at 45 volts and it showed low voltage?
it's a jikong BMS (B2A20S15P), and I run the battery between 39V and 50V.
The Multi needs at least 38V to work, and I haven't had a problem there at all.
As I wrote, as long as the public grid is available, the system won't discharge the battery below 20% (i.e. 41V).
Hello @mlau , the system started and up to 70% it was flashing red low battery level and now when it dropped to 63% (44.0v) the system stopped using the battery and now only the low battery light was on (without flashing) and it started taking power only from grid. In the inverter, I set the SOC shut-off settings to 10%, however, it turned off at 63% at 44v. Another problem was that it couldn't properly allocate how much current to draw from the grid and from the battery and solar strings. Is there a way for the battery software to overrule this charger allocation at least the CANBus ports on the CergoGX don't work either. I put the ESS Assistant on the C scale with parameters like this 2C = 39v 1C= 39v 0.5C = 44.0v and 0.1C = 44.0v , can this setting stop the system at 44v?
I will be very grateful for your assistance, because I have been trying to get the system running for 2 weeks and everything is getting confused.
I would also be very grateful if there is a way for you to send me your settings so I can apply them. Thanks in advance.
I use CerboGX, MultiPlusII 8000av, SmartSolar MPPT RS, dbus-battery with software and the same bms as yours. Best regards Kokoev
Ok so I set up the MP2s and ESS as close to the 48V battery as I could, then in the Cerbo Settings:
System Setup -> Battery Monitor : Set to SerialBattery
DVCC: Enable, Controlling BMS (last entry) set to your Battery
ESS: Mode: Optimized without batterylife, self consumption from battery: all system loads
In the Cerbo Overview screen, the central blue Victron square should say "ext. ctrl." (ext. stg. in my german version), then the charging/discharging parameters are controlled by dbus-serialbattery:
Find attached the MP2 and ESS Assistant configurations I exported from VEconfig.
