[cr34t3d_by_d4rkd3n]

the way u show is using the series principal. (flowing thru another) ur set up will work. but used to pull a winch on say a 4000lb 45 sec pull will turn that ground wire to a welding rod. the set up u show is best for a trunk sense grounding 2 batts at the sheet metal when theyre sitting right next to eachother is dumb. the more grounds u have the better. simple rule for every hot, the ground should b equil and 50 percent "fatter" .

in an engine compartment running that long of a ground is highly dangerous. surrounding positives will wanna jump to it. its better to ground both batterys to sheet or frame and jump the positives. but remember. share the load. brancch off each batt equil or else all will try to feed off one cable.