Your Daly and your SBMS0 are based on different models. In the case of the Daly it both monitors/manages and
executes battery protection. In the case of the SBMS0 it monitors/managers, but does not execute, it communicates with the other components in your system to execute protection measures.
Your Daly has large wires, because all the current flows through it, and it directly cuts off charging when it deems it necessary (low voltage, high voltage, high current, etc). The SBMS0 does this indirectly by monitoring the battery voltage, current, temperature, etc, and sending a shutdown signal to remote devices (charge controller, inverter, and battery protect), so the current isn't actually passing through it directly, and it isn't directly shutting anything off. For this reason your battery protect isn't redundant, its necessary to control DC loads.
In response to your specific questions:
- Technically nothing, it isn't between your SCC and your battery. But beyond this, its role is to manage battery health/safe charging/discharging on a more granular level than your SCC can. Your SCC can disconnect when it senses voltage is too high but it can't see cell level voltage, temperature, and so on. It may be helpful to make a distinction based on roles and responsibilities of these two components. An SCC is in charge of safe and efficient charging, a BMS is responsible for, and best capable of, protecting and managing your batteries, other components may have protections built in, but at the end of the day its the responsibility of the BMS.
- No. Well, yes and no. The battery protect isn't redundant but using the low voltage disconnect feature might be.The low voltage of your battery protect will be 'pack level' voltage whereas your BMS will be monitoring 'cell level' and 'pack level' voltage. You need to configure the battery protect to be remotely turned on and off by your BMS.
It may be helpful to spend some time trying to comprehend the design model of the SBMS0, its quite different than most BMS's. Reading
the manual is helpful but technically dense in some parts and not that great at conveying broad conceptual features.
This thread has some good info in it.