I run mine off a battery in the trailer that is connected in parallel with the trucks Battery whenever the trailer is hooked to the truck



I have installed a connection at the front and rear of the truck for doing jump starts and I use the rear to connect the trailer battery to the truck's battery and charging system
Lexan Plug Jump-Start Set with 500 Amp Clamps - Superior Signals | AW Direct

Have used the same setup on the 1995 F250, the 2002 F250 and currently on the 2008 F350
Never had a problem with alternators