Hi,
none of my chargers can deal with the 75mm long ROFIS branded protected 21700 cell. I can charge it inside the flashlight, but charging there stops at cca 4.11 volts. Therefore I want to give it a try with my LiitoKala Engineer 500 charger using some ghetto mod. I would use thick wires and fix them on battery side with rubber band or so. Any idea on how to fix them on the charging side without soldering? Perhaps some magnets or some clamps? Would this setup be relatively safe?
Wires with magnets at each end.
A cell lies perpendicularly to how the charger was designed to hold it and the terminals are connected with wires.
It may or may not be safe, depending how you implement it. However, the wires themselves might cause weirdness with the charger, because of all the electronic monitoring that it tries to do. I guess the only way to know is to try it.
What I might do instead is try to make some extension tabs out of small pieces of metal, that can be held onto the batteries with rubber bands or clamps of some kind, then bend those in a little to fit inside the slot of the charger. You could use a dummy cell or a piece of plastic tubing the length of the slot, to hold the tabs in that way.
Need to use an existing charger?
For my 26650s that need twisting and turning and sacrificing a chicken to get solid contact, I just said to Hell with it and used one of my Folomov A1s on ’em.
Often on sale, I stocked up when they were 7-8bux a pop.
Go crazy…
Not too Ghetto —- A wood dowel with wires screwed to it and magnets soldered to the other end —works very good—Always attach to the cell first—don’t want to short out your charger
It's completely safe 
and functional:
Wires soldered to magnets in case anyone is wondering. O:)
Advice: use the power on “internal resistance” test to make sure rail and contact resistances are minimized.
Cheers ^:)
The Rofis Protected 21700 fit the Xtar SC2.