Loud Alarm Sound from System
Last night around 20:30 by system started t make a very loud alarm sounding beep. I have 4 x 5.2kW batteries and the Sunsynk inverter. I couldn't tell which of these were beeping.
I went into the app and saw that the battery level had dropped to 19% and that no power was being taken from the grid. The batteries had discharged by around 20:30.
I couldn't figure out how to stop the sound and to stop the battery from discharging, so I changed the charge schedule to charge the battery at 15 amps.
This stopped the alarm, and the app showed that power was now flowing from the grid.
What couldhave caused this? I have had the system operational since June, there have been plenty of occasions where the battery is flat (at 20%) and the house is drawing happliy from the grid.
This can occur if there is a particularly high load as you approach the SOC target. The BMS controls based on a voltage to SOC converesion - and its not an exact science. You will see some overshoot - even up to 5%.
I often find that the battery will continue to discharge very slowly below the SOC target or even below low warning / battery shutdown. 99.9% of the load will be covered by grid - with <50W from the battery. I had a big debate with SS about this & they eventually said it was meant to happen!
To be on safe side, I now set grid charge on for any periods down at the 20% level - this works. Annoying - but practical solution & it costs very little.