You are making it harder than it really is
Input watts need to increase to keep output current the same as the battery bank increases in voltage. The increased battery bank voltage offers many many great advantages over our simple high current low voltage 12 volt systems.
Output current stays the same
45 amps into 12,24,36 or 48 volt battery banks
To make that happen you will need to increase the input side watts example for a (45 amp controller)
45 amps into a 12 v battery = Input side 600 watts
45 amps into a 24 volt battery = Input side 1,200 watts
45 amps into a 48 volt battery = Input side 2,400 watts
all the same percentanges hold true for 12 volt systems - 24 volt system double everything - 48 volt system 4 x everything, nothing magic or special here at all
Think WATTS
I remember many years ago at my office we had a UPS power system with a 48 VDC battery bank made up of over 60 each 2 Volt cells - I believe it was a 10KW sine wave inverter. Try that at 12 volt operation the wires would need to be 5" or more in diameter ..................
Sorry just noticed your last question the Voltage sense wire
It is needed no matter what voltage you are operating at if the system is large enough - Marc did a nice post outling the need for the sence lines at the different operating voltages
