New off-grid site with Multi RS and 10kWh Lithium (self managed, no comms) batteries. Three times over four days, the state of charge has dropped from mid 80% to 3-4% SoC instantly. This has happened at 10pm, 8am and 3 am, so not time specific, but it does happen after a large change in load (1-4kW load has come on after a period of steady loads (0.5 -2kw) resulting in some drop in battery voltage from around 53v to 51 or 52V. Generator has come on during each of these events because of SoC drop. (the SoC gen start condition has now been turned off)
Look forward to any thoughts
Maybe not what you want to hear, but a real BMS communicated SOC is best.
So try to connect the BMS to Multi RS through a Cerbo-like device (cerbo, rpi, etc).
The Multi RS can’t reliable detect/calculate the SOC only based on voltage, because of the flat V curve of a Li battery.
I assume BMS on that battery has a configuration which updates SOC based on specific conditions.
On some of the seplos BMS batteries I saw this was a normal when settings was a bit off
I have the feeling that he is referring the SOC shown by the Multi RS…
Thanks! The battery has no communications like Pylontech etc. In Australia we call this a ‘self managed battery’. So there is no BMS comms. No SoC sent from the batt.
for this case I’m usually configuring overnight charge to 100SOC schedule for the inverter and battery to sync its SOC. In DESS there is a periodical battery balancing as well