So if you go with a "cheap" relocate, you're trading off some things. And IMO, those tradeoffs do not warrant the cost savings, whether you get my kit or not, I'd recommend either doing it the right way, or keeping the battery up front and not doing it at all. And the "right" way isn't necessarily buying my kit, but wiring it up exactly like my kit because that's the proper way to do it. When you get to that point though, you'll see it's more expensive than most realize even to DIY, that you'll almost spend as much as you would to just buy my kit all done and plug & play and have a fraction of the install time.
No matter what you'll need a battery tray, and gambino sells really nice ones for under the bed (IIRC under 200 shipped), or you can get a battery box for the bed.
While many assume relocating is nothing more than extending a power cable back & grounding the battery to the frame, that setup is 1. unsafe, 2. not tech legal, 3. going to cause some electrical gremlins from poor grounding.
1. unsafe? because the battery should be fused as close as possible to the battery, so if you have a short somewhere in that cable run, you're protected from a short across an unfused battery. Factory has a fusible link, but you can't just move the fusible link to the back, because you need to step up AWG for the added length to offset the voltage drop of the longer run. So you need to add in the proper fusing when you relocate
2. tech legal? if the battery is relocated, you need a cutoff switch to remain tech legal. Some don't care, but it actually is nice having even if you don't track much, because you've got a quick cutoff source if you're doing other mods, just hit the cutoff switch and the battery is isolated. It's also good for long term storage so the battery isn't draining while sitting. I also offer a kit that is cheaper than my tech legal one though, that doesn't incorporate the cutoff switch wiring to save a few bucks
3. gremlins? Our trucks are very susceptible to grounding issues. Using the frame as a ground is okay, but for the primary power source it's not good enough. The frame rail isn't continuous 1 piece of metal, there's rivets and joints, then the body is mounted and has some ground straps, etc., then firewall body panels have seam sealer and bonding spots not full welds. So by the time you get from the PCM that's grounded to the firewall, thru the body to frame ground straps, thru the frame rail, thru the frame rivets, to the rear frame, back to your battery, it's not a clean ground path. I've troubleshot several DIY relocation setups, that simply by adding a dedicated ground from the battery all the way up to the front, 100% resolved electrical gremlins they could never figure out. And those gremlins aren't consistent either. Sometimes it'd all be fine, other times they'd appear. Solid grounding and a dedicated ground cable from the battery, all the way to the firewall is a must.
To expand on those main items, if you have a cutoff switch, it also needs to be wired correctly. It's not just a switch in-line of the power source. Because if you hit it while the truck is running, the battery is disconnected, but the alternator is not, and now the alternator is running and powering the truck, so the truck doesn't actually shut off, but the battery is isolated. That does you no good. Depending how you isolate the alt, that can also damage the alt, because there's a voltage spike when the switch is hit and interrupts all that power draw. That voltage spike can damage the diodes in the alt. To avoid this, you need to run the alt cable back to the battery side of the kill switch. That's another cable that most don't think about.
Then just for ease of maintenance, if you ever need a jump, it's a PITA to get to a battery under the bed. Mounting up a set of aux posts with aux cables is another helpful peice that most forget about until they're in the middle of it.
Then there's the materials. 1/0 AWG cable isn't cheap. Welding cable is great because it's flexible from the high strand count and prices are fair, but you'll need more than you think to do the kit wired up properly.
Also on lugs, you want a closed end, tin plated lug, so they won't oxidize. Oxidation degrades the connections, increases the resistance, and as I said, voltage issues are tough on these trucks. You want a 100% sealed connection. Exposed copper strands will oxidize over time and degrade. Now when you're talking closed end lugs, you also want to hydrauically crimp the lugs. Purely soldering is not ideal, as high current draw can melt the solder, and I guarantee you most methods of soldering lugs will end up with a cold solder joint, not a true wicking solder connection. You can back solder a crimped joint, but melting a glob of solder in a closed lug then dunking a cold stranded cable into it will not yield a good solder joint, it's a cold solder. So unless you already have the tools, a hydraulic crimper is another expense to factor in.
And you want it to look nice. Techflex is cheap, but it's work, but it really finishes the look off. But that does require fully installing your kit, cutting to length, fully removing your kit, crimping, then sleeving, then re-installing. I'm about as proficient as you can get with wiring mods, and when I DIY a kit myself from scratch, with all the resources, tools, and materials on hand, it still takes an easy 6+ hours to do an entire battery relocation kit from scratch.....since you are basically installing it twice, to get lengths, cut, remove, crimp, sleeve, reinstall. My kit is already done, already crimped & sleeved, already to length, the lugs are labeled which connection they go to, so you just start bolting away and routing the cable that's already done. You can install one in <2 hrs, where a DIY for the average person on a full relocation kit will likely take a full day to be done in the same manner making it safe, legal, & reliable.
So again, if you're going to DIY, there's a bunch of helpful information to consider, not just going to say get my kit or go scratch, but I'd definitely reconsider it. I know it's pricey, but I get to that price by adding up all the materials involved, figuring how much it would cost a DIY'er to build 1 w/ buying quantities for just 1 kit, and I add a bit for my labor. For my kits I order supplies from 5 different vendors, that's shipping charges from 5 different places. IIRC material costs are $400 to build 1 kit with the same materials. Figure you're only spending another ~175-200 more to get mine, all done, a fraction of the install time, proven design, color directions, it's usually worth the extra 200 bucks. I make it worth my time by buying my stuff in bulk, so I'm not getting shipping charges 5x for 1 kit, it's spread across getting things for multiple at a time, and there's quantity discounts on buying things in bulk. So it's still worth my while, while still trying to get a fair price out. It does seem high at first, but when you look at everything you get, and the quality of it, it quickly becomes obvious.
It's the most expensive item I build, and I've had that sticker shock response quite a bit, but every single time after people open the 30 lb box of materials, they message me back going holy crap, this by far exceeded my expectations lol. I mean I include everything down to the clamps & screws to secure the cables. Even the 18 pages of color directions with step by step install I probably have 10+ hours into writing those. You really get what you pay for.
For other folks new to this.....I've got cable kits for stock battery location that upgrades positive, negative, alternator, & ground cables, then I've got relocation kits for non-tech legal (no cutoff switch wiring), and relocation kits for tech-legal (cutoff switch wiring).
Few pics attached...
