System: off grid
-SmartSolar Charger MPPT 150/35
Issue:
The multi cuts inverting at 50% state of charge.red light for low battery on the multi and alarms on VRM. The SOC on shunt and BMS matches.
Floor on the shunt is set to 10%
Question:
I see the V drop rapidly, is this the issue or is it other settings or something else?
That battery is flat, so the shunt is not configured correctly and is providing a bad SOC.
You will have voltage cutoffs configured on the inverter, or possibly the BMS is blocking discharge as well.
I find it strange that the battery is flat, when BMS and shunt SOC is so similar at a 50% charge.
I have struggled to get them to be in sync, but for the last months it looks like they follow each other close enough.
BMS cutting is a possibility but can’t se any alarms on the bms in the time frame.
The shunt settings:
You state you have a 16 cell lithium battery, what are the specs from the manufacturer?
52.7V is low for a 16 cell battery, closer to 15 cells.
In any case, near 46V, from your image, is low for a lithium battery.
What is the inverter cut-off set to?
Even on a pylontech (15-cell) the cut-off is 44V and dynamic cut-offs are 46V, and they permit a deep discharge on their batteries.
You are right! I had issues with high DC ripple. This was caused by charging when the battery was full, and the BMS on the battery cut off. So, I turned the charge voltage down, hoping that the Victron system would stop charging earlier. I’m not sure if I needed to adjust the shunt setting or the MPPT setting, so I adjusted both.
Long story short, you are right, the battery is closer to 54V when full.
I can’t find any specific cut-off settings for the inverter, only the discharge floor on the shunt, which is set to 10%.
@Hersjoen
Cut off is set on the inverter tab in VC or VE config (you can either use voltage or SOC). These work unless you are using ESS assistant in which case the dy namic cuts off are used.
Do you have a GX or are they all stand alone components?
What are your cut off voltages on your bns set to and charged voltages?
If your cell voltage range is (a nice conservative set up) 2.8v to 3.5v so on a 16s battery that is cut off at 44.8v to 56v (abs). But both the inverter and bms have to be set to that. Float 55.5v
If that is a JK bms then your trigger for soc is also needing some attention.
