The SOC, also known as "State of Charge", refers to the battery's state of charge and is represent by a percentage by the Bluetti Power station.
On the the AC300 and AC500 power stations you can set a custom range in the UPS Settings for SOC High and SOC Low to control "when" and "how much" the battery will be charge by the grid, which is defined by the SOC High settings.
However, the SOC Low setting is suppose to, and according to the on-screen documentation do the following:
"Battery SOC low - When the battery is drained to this value the AC[3/5]00 will automatically cut off power output"
This SOC Low setting is suppose to protect your battery from dropping below a set threshold and prevents your battery from draining to 0%. This is important because you may need to reserve power for emergency use, but more importantly your head-unit (AC300/AC500) will not connect to a battery that has a 0% State of Charge (SOC). When a battery drops to 0% you may have to recover this battery by disconnecting it from the head-unit and externally charging it from the side PV/DC inputs. This can not only be very inconvenient process, but not all owners may have the ability or or equipment to charge their battery external (T200/T400/T500 or PV).
The SOC Low setting is an important setting that should be enforce as described. In the below video I will show you that the SOC Low setting is set on my own personally system and is ignored.
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