relocated battery issues

hey guys, long time no talk, its been busy these day but ive got a problem with my truck. i relocated the battery to the bed of the truck a while back. i ran 2 ga. power cable (the red audio kind) to a terminal that i put up in the engine compartment so the fuse box hooks up like normal. it was recommended that i put a fuse in at the battery to prevent any shorting or damage to the electrical system; however, the truck blows fuses like no other. the truck usually sits for about a week and ill drive it on a weekend but every time i go to start it is crank for a few seconds, then pops the fuse. the fuse is an 80a fuse. i used a 100a at one point but haven't been able to find them. both size fuses blew trying the same thing. i am now hunting down a 120a circuit breaker to hopefully fix the problem. what have you guys done with your relocated batteries? do you or have you had this problem as well? i thought of putting welding cable in for power wire, and possibly wiring the battery to the relocation terminal without any fuse.... is that the correct way or no? any help is appreciated.... thanks guys!

Where is the battery grounded? I have 2 batteries mounted in the bed. Both are grounded 1' from the mounting location. I have a 120amp fuse for each. Both batteries then run to a switch. It switches from 1 battery to the other, both or none. I ran 0ga to a distribution block, then 2ga to the fuse box. The battery that powers the starter, and truck's electrical also powers the airride. The other one only powers the system.
So, I'd install a large 12o amp fuse, ground the battery within 1 foot, or check the ground at the battery. Ground the block to the frame, and see if that helps. Make sure your grounds are all making good metal to metal contact.

The fuse size should the same as the alternator output! No bigger!

Mine works fine.

what is the alternator output rated at? (for a stock alternator)

currently the battery is grounded to the frame. the ground wire is roughly 16 inches and also 2 ga. i was thinking of putting in a distribution box today, however, i was looking for one and cant find one that accepts anything bigger than 4 ga wire. also that same distribution block only had one 4ga. in and two 8 ga. outs... which i think is to small for what i am using the power for. does anyone have any pictures that could add some insight? thanks for the help guys!

Is the engine block grounded to the frame also? You would need to buy any 0ga or 2ga stuff from a place that sells car audio/video. You might have better luck at smaller privately owned shops. Stock alternator amperage is around 80-90. If the engine is not grounded, that is the first thing I'd do.

All of my distribution and connectors are Memphis Audio brand.

Stock is 60 amps & the fuse is in the engine bay @ the main fuse panel ( it bolts into the holder from the bottom)

i ran a 2 ga. ground from my battery to the frame rails. 8 ga. ground wires from my firewall to the frame, and i believe i put a 8 ga. ground from my engine block to the frame, but i will double check that one tomorrow to make sure. im certain they were 8 ga. grounds, just cant remember how many of them there are. haha.

okay guys, well im at wits end with this thing... i got a few minutes to tinker on it today and this is what i found. i keep blowing 80 amp fuses. i ended up charging the battery over night and my charger said it took 100 percent. i put it in and sure enough, poped a fuse as i turned my ignition on. so i thought maybe the power wire is trashed. i hardwired it with a set up jumper cables and the truck cranked over fine, but wouldnt start. within three cranks, my starter started to wind down and it felt like the battery was almost dead again. my gauge says it has 12 volts.... i plan on replacing all the wiring. do you have any recommendations on what wire size and type? currently everything is 2 ga. a buddy of mine said that there is such a thing as having too big of wire. also he mentioned that the 8 ga. ground i have from the engine block needs to be the same size as the power wire. he was saying that the power wire is only as good as the ground. money is not a problem at this point, im doing this a second time and i want to make sure its done correctly. any help is apprieciated.

oh one more thing, if my starter is getting weak, would it draw more power to turn over the motor? when i rewire everything, i dont know if its worth changing as well... thanks again sorry for the story. haha.