Hi!  My 2008, V8 Pathfinder that just rolled over to 200,000 is having some weird issues.  Over the last four years I have ended up with a new battery each year and an alternator almost every other year.  I am not the brightest bulb in the box but I do know there is more at play with my car.  Currently I own a brand new Interstate Battery, a two year old alternator (that tested good), and my headlights and instrument panel “pulse” or to some “flicker”. 

HELP!  Do I have a relay problem?  Belt?  Bad Driver? 

Sounds like earth straps are poor and need replacing or adding more to provide a route to earth for the current to return to the battery....seen it on Nissans before