what he said ^ , plus the device itself might have a lot or little resistance from the switch and wiring in it too.
so when the question comes up, the differance can be all the differance in the world, even from non-copper wire to copper wire.
the resistance of the actual battery used, all that stuff.
even how well the item can be cooled in the device.
chances are good that you can get away with it, or at least with a 1-.5ohm of added resistance, but its really going to depend a lot on how its all connected up.
just wiring it up with cheap wire can put enough resistance in sometimes.