how the battery behaves in this diagram

My question is this. I'm using this ic mppt SM72445 along with a 250 watt solar panel, mppt output configured to 50.4 or 51 volts, 12-cell lithium-ion battery pack and bms, if the load is less than the output of mppt the battery will be charged, but what happens when the load is greater than the mppt output and there is a voltage difference between the mppt output and the battery? example ; mppt output = 50.4V 5A / battery pack = 46.8V 3.9Vcell * 12 / load = 10A my doubts are for the difference in voltage between the two sources, mppt and battery in parallel

 

The MPPT output and the battery are in parallel so the voltages across both will be the ≈ same. One way to treat this circuit is to make the MPPT output a current source and the battery a voltage source. The MPPT current source voltage @5A max current (with the battery supplying the remainder of the current) will follow the battery voltage until the MPPT output voltage limit is met.