I'll start with the electrical rundown- EA 220 amp alt., big 3 in 0ga, xs d2400 under hood, deka 100ah g31 agm in trunk, 1 pos. run 0ga between batts, all cable is ofc. Now for the questions, first the alt- i was told that the bolts holding the alt in place are all the ground you need but i feel like i should have a 0ga ground also. good idea? unnecessary? Now for some fusing-how should my pos. between batts be fused? i have an aq3500d.1 about to go in, do i need to fuse for its 400 amp rating?,fuse for the max current capacity of the cable at 15-20ft?, fuse for the max amt of amps that my alt and front batt can deliver? Are there any performance differences in anl vs. the multiple midi mini fuses? Now for the cable- how beneficial is a run/s of neg. between batts? Is it necessary to do a 2nd run of pos.? Seems to me the one run should be more than adequate to carry all the current the alt+front batt can give to the back batt/amps but i have certainly been wrong before. Thanks in advance for any and all help, to those tempted to tell me that u never fuse and its not necessary u can save both our time and not post, thx.