My slip ring at a bottom of a tower for easy access 2 years no problem hope to stay that way.
It is nylon housing with brass rings and fingers ,spring loaded ,pact with silicone grease(electrical).
Inside shaft runs on 2 bearings so it is ease to turn even trough is not spinning a lot, cable absorbs some twist.
Going to 48v allows you to use smaller slip rings and .My brass on brass setup works good and not damaging rings or fingers .