I have a MPPT 75/15 and the specs say the terminal fits a 6mm² cable. I tried that cable size and it does not fit. Without a wire end ferrule it may go in but just and it is a hassle, some strands being bend and staying out (not good), with a crimped ferrule of the correct size (it tried two types) there is no way this fits.
I have some pre-crimped cable from the solar panel (this is a kit) and the ferrule there look like a size too small and it is a 10 gauge wire which is slightly smaller than 6mm² as well. And even that barely fits.
So what am I doing wrong? Do I need to switch to 4mm² cable? It is only the 1.2m length from MPPT to battery, but 6mm² cable is what I have....