I need to relocate my battery box so I can throw another rack of fuel tanks on the F-800.
My positive battery cable is like an inch thick. (The copper inside, not the rubber casing) On one end it has the eye that bolts to the starter, and on the other end it has a 3 way "Y" with three short cables that go to three batteries.
I can't order a longer cable, so what I want to do is splice the similarly huge cable from my parts truck into my current cable, thereby giving me the added length to put my batteries where I want them.
My thought is to get a short peice of copper tubing with an I.D. similar to the O.D. of the cables, pushing the cables in until they touch, crimp the tube down real good on both ends, and solder the hell out of it, then cover it with shrink tubing.
Why is this a bad idea?

I did this to one of my cables over 3 yrs ago when running a winch hook up to the rear end.....never had an issue with it, sealed it up with shrink tubing then overlapped with elect tape.

I would think that your idea would probably work fine.

If it were my truck however I would get an insulated stud that you can mount to the frame and then put ring terminals on the ends of all the wires that need to be connected and stack them on the stud. That way there wouldn't technically be a splice in the wire but rather a junction that may be easier to repair on the road somewhere if needed.

I'd skip the solder. Solder creates a hard point for a potential fracture. If this cable is going to see vibration and flex I'd just double crimp and heat shrink.
I'm not allowed to use solder on connectors on boats for this reason.

i don't know why you can't get longer cables??? go buy a 1000 foot roll of welding cable and you can make battery cables as long as you like. i know that napa can make custom battery cables to virtually any length you could imagine.....i'm not understanding you correctly or something....

Like you said, Thin wall copper tubing at your local hardware store.


edit: i would try to overlap the cable within the tubing b4 crimping.

Or go to NAPA or your nearest truck shop and buy bulk cable and the lugs and a crimp tool and make your own cables. Or just buy a foot of cable and a tool and a 2/0 "butt connector"

Here is a start

http://www.napaonline.com/NOLViewer/Pages/Results.aspx?Ntt=battrey%20cable&ShowPics=1&No=0&Nty=1&N=30070&Ntk=Keyword

I would think that your idea would probably work fine.

If it were my truck however I would get an insulated stud that you can mount to the frame and then put ring terminals on the ends of all the wires that need to be connected and stack them on the stud. That way there wouldn't technically be a splice in the wire but rather a junction that may be easier to repair on the road somewhere if needed.

I like this idea. It could double as a jump start lug if you place it right.
Travis..

something like this?

http://cgi.ebay.com/ebaymotors/2-0-awg-Tinned-Butt-Splice-Heat-Shrink-combo-UL_W0QQitemZ290180209128QQcmdZViewItem

although, I think your way with copper would be a better connection

or

http://www.who-sells-it.com/ctp/4611/1/full/

or

http://www.wiringproducts.com/index1.html

Split bolts

http://images.orgill.com/200x200/6174304.jpg

Solder on big cables is a bad idea. You end up with solder wicking up the cable making it stiffer and more likely to crack. It also causes a "cold joint" issue where the bond isn't as good in the middle. A properly crimped connection with dielectric grease liberally applied before crimping is far superior from both a mechanical and electrical perspective. Shrink wrapping afterwards is also a very good idea.

I learned this when researching electric powered automobile conversions dealing with massive battery banks, but I'm too lazy to look up the link for you.

The e-bay link above goes to a 2/0 sized splice. The same guy also sells a 4/0 splice. If your cable is bigger than that then you might need to go visit your local power company and see if you can talk one of their guys into splicing it with something intended for commercial power supplies.

If you go to an electrical supply house most can order diesel locomotive cable. It has lots of small wires like welding lead so it is really flexible.
It comes in all kinds of wire sizes I have bought it as large as 750 MCM and as small as 4-0.
You can get standard crimp connectors and use a hydraulic crimper to splice what you have or just run a new one.
Also put No-Ox in the connector to stop corrosion.
If you are going to make a mechanical joint I would use a Polaris Connector (http://www.dale-electric.com/pdf/page108.pdf) connector not a split bolt.

That Polaris Connector looks like the best solution presented so far! A little pricey, but it would remove all doubt about doing it right.

I like this idea. It could double as a jump start lug if you place it right.
Travis..

I used to work for a company building fire trucks on MDT chassis and any time that we needed to relocate batteries that is how we did it. I'm sure that there were possibly better ways to do it, but it was honestly the best "one size fits all" solution that we could come up with since there was always more than just battery cables attached to the batteries. To the best of my knowledge, we never had any issues with doing it like this and there are plenty of trucks out there on the road that have their battery cables run this way.

You could also take the end of the wire you need to make longer, as well as the end of the wire you are going to add to it and strip them both back about 2-3 time the diameter of the wire.

Fray the wires so they fan out.

Now slide these 2 fanned out sections of wire into each other as tightly as you can.

Flatten the frays out on each other.

Now, take a length of small diameter wire and wrap around these frays as tightly as you can, covering all the exposed joint.

You can solder it if you want, or just shrink wrap it.


If you do it right, it will be just as strong as the original wire, but only slightly larger in diameter.

Any electrical supply house will have the lug style like the Polaris in the size you need for a reasonable price. I use them on my front winch and battery with no problems. Like said before, just insulate them well. I use 10 mil tape over them with a wrap of good electrical tape to hold the mil tape on.

Skip the polaris type connections for the road. Vibration will cause them to loosen up and cause issues. Go with the stud and crimp ends and bolt it up tight with lock washers. I get service calls all the time about flickering lights in houses and these type of connections are always the problem. The wind moving the service drops all the time just cause them to work loose over time.
I would skip all of that and replace the cables with longer ones, the least amount of connections the better.