In your case, you don't have to, but it doesn't hurt.

 

I ran the battery cable through the trunk floor. The rear frame rail had a hole from an old exhaust hanger. I burnished the perimeter clean, used a 3/8" grade 8 bolt, star washer, lock washer, torqued the snot out of it, then sealed.

no ground problems in 5 years

 

The star washers will help, just add some antioxident when you connect them. 4AWG will be fine on those short runs. I even use with trunk mounted batterys without any issues. The key to making or buying a good set of cables is the terminals (brass) and how they are connected. I like to make my own and crimp solder with a little heatshrink. The cross linked polyethylene is a big plus over the vinyl type insulation and will not quickly break down when exposed to heat. The cable on your link appears to have all the goodies and has the good insulation.

 

That is what I was hoping for. Like I said, the majority of the cables out there are 4AWG copper. There are some 1/0 cables I've found but they're around $100. I'm not paying that, geezh. My longest run is at least 36" from the solenoid to the starter, and I will probably use 4AWG for that, since that seems to be adequate. Evil, you say you use 4AWG for the run to the trunk w/o any issues? If that's the case, I think the 36" length to the starter should be fine. The only current on that wire is at start up.

I do like james' method to grnd the wires to the frame.

 

you could always use car audio power wire and wrap it in wire loom if u don't like its look

http://www.knukonceptz.com/productMa...y=Power%20Wire

 

I have an uneasy feel about 4 gauge when starter draw might be running up toward (or possibly above) 200A. I realize that it's not a continuous current load, so overheating and house electrical code ampacities may be a little too conservative.

In more of an automotive environment . . . still for continuous duty

I would not go any lighter than 2-Ga for 4 ft even if I had to make up my own cables with wire sourced from an electrical or welding supply house. Zero-gauge or heavier for trunk mounted batteries.

4-Ga is quick and dirty just-get-it-going-again stuff made to a price point.

I also prefer welding a ground stud to the chassis for that separate pigtail if it is at all possible to do so. One less pair of surfaces for corrosion to get in between.


Norm

 

I thought about running 2AWG to the starter from the solenoid. That is the main current draw in the system and the longest wire, in my case. I think 4AWG wire should be fine for grounds, since that is in fact all they do. The other wires, I am installing a master disconnect latching solenoid, are no longer than 10"-12, and was planning on 4AWG for those short runs, but may run 2AWG for those. After start up, the continuous current draw should be small.

The problem is finding the correct wire that will hold up to vibrating and will not break loose over time. It must be automotive type of wire, like what NAPA sells. I looked at some of the electrical supply houses and they suggest against using what they sell. They do sell wire like S-O cord but it is more than one conductor.

Am I thinking along the correct lines here?

 

You want your ground to be at least as big, if not bigger, than your starter lead. Remember, current has to loop back to the battery.

But honestly, I think you're stressing about this too much:P Most vehicles use 4ga cables and work just fine. That 3 seconds of starter draw is not going to melt a 4ga cable, even one 36" long. You should see the positive cable on a late 80's F150; it's about 5 feet long (built into the wiring harness) of 4ga. I'm running 2ga, just to be on the safe side, but IMO anything more than that for an under-hood battery is way overkill.

If you want something really slick, go to Napa and buy some bulk cable, a couple different ends, some solder (pellets are available), and some thick-wall heat shrink.

 

The key is continous load. If you are pulling 135 amps plus (which is about what a short run of 4 will handle continous) a 4 will do the job. Welding cable is OK size wise, but over the years I think you will have trouble with the insulation breaking down (heat, petroleum exposure, yada yada). Again I will stress the word "Quality" as there is a lot of crappy wire on the market (float boat stuff). On your question about the 4 from the trunk, its on a 13 to 1 compression race engine with a mini starter. The run is like 12' to 14' and I have had no issues. Your runs are very short and the 2 will be overkill, again most often the weak link is "NOT" the wire, but the terminals and/or their connection. Even the solenoid contacts will most often go well before the wire. I have two trunk mounted batteries and both are run with 4. One actually has a 180 amp alternator, no heat and no issues. I would not recommend the SO type cable at all for your purpose, again look for a cable or wire with cross- linked polyethylene insulation (most marine wire will be this). ALso a little armor on the starter wire may come in handy, as this a trouble spot. Most of the time you will need a clamp to secure this cable and its prone to wear thru the insulation over time and ground out (the one in your link is armored).

 

OK, thanks all. No more stressing! I will stay with the stuff in my link, cause I like it, and it will all be 4AWG size. That was my initial plan anyways, funny.