Question about soldering battery cables

41woodie · November 09, 2010, 07:47:29 PM

Using 1/0 welding cable for a rear mounted battery in the woodie. I want to solder the lugs on the cable but in the past my success with soldering large cable has been pretty dismal, burned insulation and other bad stuff.
Anyone have any hints as far as tinning, flux, heat source etc. I have a conventional torch with a rosebud tip as well as a Henrob/Cobra/Dillon torch. Any advice would be helpful.

enjenjo · November 09, 2010, 08:09:18 PM

I use solder slugs. They have solder and flux in a slug that will fit in the terminal, different sizes for different size wire. Just heat the terminal with the slug in it until it melts, insert the wire, and let it cool. Shrink tube over it, and done. The local NAPA store stocks them.

41woodie · November 09, 2010, 08:48:48 PM

Great info, I never knew the slugs existed. Looks like exactly what I need. Thanks I'm off to NAPA tomorrow morning

Beck · November 09, 2010, 09:20:13 PM

My local street rod wiring shop is owned by a friend. He turned me on to the fittings with the solder slugs. They work great. If you overheat the fitting the solder will still wick up the cable. When this happens there isn't enough solder left in the fitting. Have a roll of solder handy when you install the ends. If it isn't full add more solder. Since it was overheated you will probably not have to add any more heat. Getting it just hot enough takes a little practice.

58Apache · November 09, 2010, 11:31:55 PM

I read somewhere that you shouldn't use welding cable for battery terminals. Something about the insulation not holding up in an engine environment?

I just used a large terminal lug and a propane torch and tinned the cable first and tinned the inside of the terminal by itself., Then heated the terminal as I slipped in the cable, kept the heat going for a few more seconds until I was sure the solder on the cable melted.

Slid the heat shrink up, used a heat gun on it, and done.

41woodie · November 09, 2010, 11:55:00 PM

I would agree on some of the poor quality welding cable being imported. Some of the stuff is extremely stiff and if you twist the wire the insulation separates from the wire and liner.
Some of the better cable has cross link poly insulation like the high end wire in the nicer wiring kits. In addition since I'm coming from the rear of the car the cables will not be in the engine compartment other than crossing from the frame to the starter solenoid. The insulation is good to 125 degrees celsius, 257 fahrenheit. Hopefully the cable will stand up well and provide long trouble free service. At least that's the plan.

phat46 · November 10, 2010, 07:22:06 AM

I had heard several times by "experts" not to solder battery cables; something about the flux working its way up the strands and corroding them. I guess if they make those slugs for it and so many people have done it successfully that must be a myth.

Beck · November 10, 2010, 08:29:34 AM

Quote from: "58Apache"I read somewhere that you shouldn't use welding cable for battery terminals. Something about the insulation not holding up in an engine environment?

I had also heard not to use the welding cable, but didn't know the reason why. I have used the battery cable in all of my past rods without ever having an issue. I do use top quality cable.
If you add solder to the slugs as I suggested earier it would be best to use solid solder, not flux or rosin core.

wayne petty · November 10, 2010, 08:41:16 AM

how many people carefully seal the base of the battery top posts to the battery top with a ring of silicone?

so that no vapors can come up through the tiny gap that exists... (where the lead posts stick through the plastic top)

it prevents battery terminal corrosion if done right..

enjenjo · November 10, 2010, 11:38:56 AM

Quote from: "wayne petty"how many people carefully seal the base of the battery top posts to the battery top with a ring of silicone? so that no vapors can come up through the tiny gap that exists... (where the lead posts stick through the plastic top)

it prevents battery terminal corrosion if done right..

I use the anti corrosion rings from NAPA, available other places too. They seem to last as long as a battery does.

The key to using welding cable is sealing the wire itself from any exposure to moisture. It is very good at wicking moisure the full length if it's exposed anywhere. I have seen power cables on salt flippers that had slimey green corrosion the full 30 ft of the cable in only a couple days when not sealed correctly.

On a similar note, I had my Pontiac in for service this week, the shop asked how long the battery had been in the car. 10 years last month

I had him install a new battery.

41woodie · November 10, 2010, 11:53:37 AM

On this application I'm using a pair of PC925 Odyssey batteries that are "supposed" to be pretty good about not out-gassing. I plan on sealing the terminals on the cable with the good quality shrink tubing that is adhesive lined and really does a nice job of sealing.
A lot of good info coming out in response to my question, as usual. Thanks to all.

papastoyss · November 10, 2010, 02:26:36 PM

I have a tool I bought at a swap meet long ago to crimp the lugs onto the cable. It is a cast housing w/ a v shaped anvil in the bottom ,a plunger that slides down thru the housing to crimp the lug. I use my bearing press for pressure but a bfh would work as well. If I weren't such a dummy I would post a pic of it.

phat46 · November 10, 2010, 03:49:12 PM

Quote from: "papastoyss"I have a tool I bought at a swap meet long ago to crimp the lugs onto the cable. It is a cast housing w/ a v shaped anvil in the bottom ,a plunger that slides down thru the housing to crimp the lug. I use my bearing press for pressure but a bfh would work as well. If I weren't such a dummy I would post a pic of it.

I made one of those at work years ago....after I was told you shouldn't solder them.... :?

41woodie · November 10, 2010, 04:51:46 PM

Other than the problem of hot solder wicking up the strands and making the last few inches rather brittle what would be the problem with soldering them? With the solder/resin pellets, mentioned earlier in the thread, being marketed it appears that someone solders battery lugs.

Seems like properly done soldering would produce a more electrically sound joint than crimping would. The crimp would not be in physical contact with all of the strands like solder would. Of course if you want to extend my reasoning why would they make crimping tools if soldering is so great?

Seems like it would be more a choice of skill and preference rather than right and wrong, but what do I know.

papastoyss · November 11, 2010, 11:23:28 AM

Quote from: "41woodie"Other than the problem of hot solder wicking up the strands and making the last few inches rather brittle what would be the problem with soldering them? With the solder/resin pellets, mentioned earlier in the thread, being marketed it appears that someone solders battery lugs.

Seems like properly done soldering would produce a more electrically sound joint than crimping would. The crimp would not be in physical contact with all of the strands like solder would. Of course if you want to extend my reasoning why would they make crimping tools if soldering is so great?

Seems like it would be more a choice of skill and preference rather than right and wrong, but what do I know.

On a SBC w/ old style Delco starter I usually need to make a tight turn in the cable at the solenoid in order to keep the cable away from the exhaust. Cable needs to be as flexable as possibile so I crimp instead of soldering.