I had a problem with one truck once and just added a battery.
My standard light package:
Dump Trucks (small or big) : A strobe on each side of the cab protector, strobes recessed into the rear or the body, and back up lights.
Pick Ups: One strobe (mag mount) on the middle of the roof, the newer trucks are getting a ladder rack, with the a mini edge bar, back up lights
Loaders and other equipment, Dual strobes on the cab, and back up lights.
The powerstroke with dual alternators equals more than enough power.
Geoff