This is some ACTUAL figures to show what you need for a power supply for a full 40A charge rate
Here I am using a SHIRLEY power supply. Its set to max Amps (50). And to 25.5V.
PL8. Obviously.
Charge at 40A.
Power supply at 48A. 8A wasted. Or 16% wasted. I might add that the power supply fan starts winding up like a jet engine at the 5 minute mark!