Suggest 6 volts test as it is easier. Seeing is believing :)
I was suggesting the higher voltage with somewhat lower amperage will blow first. Not that the fuses could withstand over-current for a reasonable length of time.
It is a tendency, not an absolute. Otherwise all fuses would be the same.
Protection at high current inrush has been an issue with low voltage DC motors because of fuse behavior. The answer has been to over-size the wire. I had problems with the functional protection of a decade resistance loading (Nichrome wire) 400 ampere alternator test bench. I had to try and satisfy the inductive solenoid loading progression. i.e. tungsten element inrush. Protection at 11.5 volts to 15.0 volts. I finally had to settle for 100 amp increments, 50, 25, then final load with a 50 amp rated carbon pile. Not too difficult, right? Oh my. 12 volt, 24 volt and 32 volt. Things got complicated.