AC500 Charging scenarios

Looking for help on how to trigger AC500 to start charging from Grid power at a specific time or whenever the battery reaches the minimum SOC?

I have two AC500 units running in split phase mode, each with one B300S battery attached. My issue is the two batteries deplete at different rates which is ok until one depletes completely and the entire feed into my house shuts off. Is there a way the system knows not to deplete one battery completely until the other battery equalizes? Would appreciate anyone’s help since this forum has become Bluetti’s method of support. I am so disappointed in after sale support that I don’t even try calling them anymore. Thanks in advance.