Copper wire gauge vs length, batteries at opposite ends of truck?

So I've spent years off-and-on searching for a dual battery tray for my Sport that I can just bolt on and go, no other modifications. The Sport has a brake pressure equalizer coil thingy near the passenger side firewall that precludes that area for any of the available 2nd battery trays.

Since MOLE Overland: https://web.archive.org/web/2025020...oduct/gen-3-tacoma-side-by-side-battery-tray/ is out of business, I've been looking at Juniper Overland: https://adventurevehicleoutfitters....-side-dual-battery-kit?variant=49872691396930 -or- JD Fabrication: https://jdfabrication.com/collectio...ondary-shocks-for-4-lt?variant=41535548326003 as alternatives.

Sticker shock on Juniper means I won't buy it because I already have the Redarc BCDC and when I called and asked they would only reduce the kit price by about $100 so screw that. So now I'm left with cutting a hole in my composite bed where the factory storage box USED to be put (damn you Toyota!)

This brings me to my question about how long a copper cable can be. If I use 0/1 wire and string it all the way from the back of the bed to the front of the truck, around 13-15'ish feet, will there be any voltage drop issues for the Redarc charging?

Not sure I believe it, but google says a 4-inch diameter copper wire can carry 12 volts DC over 100 miles with a voltage drop of only about 2.775% -- really? That drops 12 volts down to 11.7 volts. So if you had 4 inch diameter jumper cables you could really jump start a car 100 miles away??

 

100 miles sounds like a Google AI hallucination. Wondering what 100 miles ×2 of 4-inch dia copper would even weigh... (or cost, for that matter lol)

This chart was posted in another thread recently... Maybe help?

 

I have a Redarc in the bed of my 2020 long bed and have never had an issue. Alternator power or solar power.
https://www.tacomaworld.com/threads/vagabond-drifter-camper-buildout-and-mods.540940/page-290#post-26127489

Message me if you want to see what I did.

 

I think it's safe to say that you can get a set of good jumper cables and cut the clamps off. Or similar sized wire if you can get it cheaper in bulk.

I did similar to run an inverter and air pump in the back of a 2000 Nissan Xterra.
Was already shopping for some wire and stumbled across a set of industrial 24' jumper cables at a garage sale for $5. So I made the industrial set my main set and then cut up my existing cables for wire. Wished I had done it the other way because the industrial set was big, long, heavy, not very flexible, and coiled up the diameter of a donut spare tire. Probably weighed the same too.

 

Op- if you do a dual battery kit(mounted under hood on fender), the inner fender liner and core support will crack with mild off-roading. I have had mine repaired(welded and plated on backside) a few months back, but it seems every trip i spring a new crack. Will be ordering the JD fab kit to relocate the battery to the rear instead of over the wheel/headlight, then fix the fender liners and support. Factory core supports and fender liners are thin gauge, glued and “spot welded” together(most cost effective, but least structurally stiff[likely for crash ratings now that i think of it]). It’s a common issue with the weight of the battery over those “supports”

 

Don’t over think it. DC in not like AC, length matters! Determine your load (amps) and length and do the calculation from a chart. Don’t do the jumper cables hook up. They expect short term use and are not rated for heat dispersion long term. Think about making it a short as possible even if you have to reposition stuff.

 

I put in a 4/0 Marine grade (tinned strands) from front to back. My application is powering anything I may install in the future as well a rear winch. Using the frame as a ground return. Currently on this run is a refrigerator and inverter; while using the winch it won't matter what the other power users are getting as voltage, as winch use is intermittent.

 

You don't think 1 or 0 AWG is good enough? 150a at 12 to 13 volts is like 1,800 to 1,900 Watts. And he's just charging that battery in the back with it. Then that battery supplies the real current.
Yes, I'm challenging the statement you made, but with curiosity to learn. How thick should that cable be?

 

I went off the Redarc chart which called for 4 gauge for that distance.

 

It isn't a one-way circuit. If the battery is charging off the alternator, it's also available to supply power to the rest of the system, just like the battery up front. The wires have to be sized for the load it could see, which could far exceed the charging current.

 

^this, but CTEK in mine

https://www.tacomaworld.com/threads/great-white-taco-build.424430/page-629#post-27356713

 

This is largely unrelated to the battery. I only went up one battery size, and my passenger side has identical damage and I've added zero weight over there. It's got a lot more to do with how hard I've been on the truck off road vs the weight of the battery itself.

 

This is good to hear, as I have put two Optimas in the original battery position and one over on the passenger side just forward of the firewall. "Knowing" about the sheet metal fatigue I beefed up both sides after hearing about the problems with battery weight.

 

Agree as well. That seems more like metal fatigue from flexing of the truck & suspension over off-road undulations (urethane body bushing kits are said to increase the stress on those areas too, which would make sense since they allow less movement between the frame & body than rubber does).