All settings in BMS are ok, its a LFP 16S 48V system with sustainvoltage at 50v. It cuts off at 51,1 volts (which is around 17% SOC) while I want it to be able to discharge to 10%. It keeps giving low battery alarm also. Why is this happening? Used the default settings in VE config for LFP batteries for dynamic cutoff etc. Also have a 15S ESS with exact same settings which go's to 10%. I dont understand whats going wrong here
Hi @banne
Got a couple of guesses for you:
When you say cuts off what do you mean? As in the battery disconnects and can't be seen by the Victron system at all, as though it's been physically disconnected?
If so my guess would be it's the BMS that's causing the issue/disconnecting the battery from the system. If not due to an incorrect setting then maybe due to individual cell within the battery pack dropping below a minimum voltage or something along those lines.
If this is what is happening when you say cuts off i would first monitor the BMS data as you approach 17% to see if there's something setting it off ie an individual cell voltage dropping or maybe a rogue setting somewhere.
If instead when you say cuts off the battery is still visible and the victron system is keeping the battery at 51.1 volts then that to me says maybe the victron system is the limiting factor. And maybe reapplying the settings again from scratch/double check the variable min voltages are set when setting up ESS.
If it is the victron system rather than the BMS I would expect you to have an alarm/notifcation in gx device. (Tbh alarm/notifications may also be available if it's the BMS if BMS coms are setup).
C rating cut off Alexandra refers is the various cut off voltages at different discharge rates set in ESS assistant.
Given MP says battery is low in alarms I think Alexandra is right it'll likely be those settings and not the BMS.
You can probably look through the VRM data to confirm voltage at the cut off time. I imagine what has happened is you have some slightly larger load on the system at 17% and then the voltage dips just below one of those C rating cut off voltages.
As Alexandra suggested I'd probably start by double checking those settings keeping in mind that there's a larger voltage drop the more current you're drawing from the battery (ie at higher C ratings).
Before someone else comments saying your comment is wrong: (Your comment sounds confusing as the C rating isn't really "for the inverter" it's a measure of speed in which batteries are charged/discharged but I know what you're saying.
And yes you're right the settings are set in VeConfigure/the inverter. So you're setting the cut off voltage for the battery at C rates/(discharge rates) within the inverter settings)
