I like those ferrules, but I find that the #4 set-screw terminals in some cases won't quite take all the strands, which need trimming and twisting real tight. So concern would be if the ferrules actually fit. At least a ferrule would be easier to get the set-screw to hold tight to and not have the wire slip out.
It would not matter for voltage drop if you used a thinner ferrule and got as many strands as possible in that. Be like having a short but thinner pigtail where it is so short it does not make for a high R.
I had to use a strain relief trick with one of my set-ups (photo to be found maybe) because of that and no ferrules, with a 100 amp charger that needed fat gauge wires. (In that case it was a cut off set of #2 cu-al jumper cables. The cu-al was ok as long as you oversize it compared with cu.) With ferrules, I would not have needed that strain relief I think.
In this case, I would just go to the auto store and get two 3 ft long #4s with lugs on them, cut off one end, and use the next size down ferrules to be sure they fit in the set-screw terminals.
https://www.canadiantire.ca/en/pdp/motomaster-switch-to-starter-battery-cable-4-gauge-0110961p.html
