Ah one of those blue PWM controllers so anything goes with those things. Can you post a readable picture of the instruction leaflet that came with it? The leaflet that comes with them can occasionally, just occasionally, related to the operation of the unit.
I know what I'd say is high voltage disconnect, but what the writer of the firmware / leaflet thought it meant could be something completely different. The ones I have here in the junk box don't mention this option at all.
Low voltage disconnect for the load is entirely up to you, based on how far down you want to take your battery in terms of state of charge. The voltage you need to configure depends on the SOC as well as the amps drawn by the load so you need to work out what the voltage on your battery will be at that point with your load connected. 12V 9AH battery gives coarsely 108 watt hours (12 x 9) at full discharge.
1. measure amps drawn by the load (let's assume 2 amps).
2. multiply measured amps by 12v to get watts (24 watts).
3. divide desired battery discharged point watt hours by watts (50% of battery = extract 54 watt hours, so 54/24 gives you about 2 hours to run).
4. fully charge battery
5. connect and run load with no solar input for about 2.25 hours and while under load note the battery voltage. This is voltage your low voltage disconnect setting.
If you want to just run into a brick wall to stop overdischarge of the battery but don't care about SOC, life cycles etc, set it to 10.7
Load on is again up to you and varies. You want to bring your battery up high enough so that when the load is reconnected the voltage does not immediately collapse down to low voltage disconnect point. Some experiments would be needed to set this properly but again you could just take a stab in the dark and say 13V.
