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January 20th, 2007

Soldering Battery Cable Terminal Ends

Here’s another Quick Tech Tip From the Garage of Tom Zuloaga. If you have ever installed a trunk mounted battery box, or a master cut off switch, you know doubt had to buy battery cables to make the proper connections. This tip will show the best way to make high quality soldered connections on battery or starter cables. You might have to cut a cable you already have or you might be using welding cable that you have bought in bulk.

You can buy different size copper terminal ends at welding supply houses or even home improvement stores such as Lowes or Home Depot. Choose the terminal that best fits the cable you are using.

The next step is to strip off 1/2″ of the cable insulation.

A terminal end in then clamped into a vise.

Next, a 2 1/2″ piece of solder is slipped into the open end of the terminal and heat from a small propane torch is applied to melt the solder in the terminal.

While the solder is still molten, the stripped end of the cable is inserted into the terminal and the torch is removed. Hold the cable in place for a few seconds and the connection will harden.

A piece of heat shrink tubing placed over the connection will keep it weather proof. If you can only find black cable, red heat shrink tubing on the positive (+) cables will help identify them. The small propane torch can be bought at any hardware store and is very inexpensive. It can be used for soldering cable terminals, heating up parts for assembly or sweating a broken water pipe. Good luck.

For more information or questions about this Quick Tech Tip please contact Tom Zuloaga.

By 67stang @ 9:40AM PST.
Category: Tech Articles
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  • 1
    avatar mel says:

    Dont think soldering high current cables is a good idea.
    Having worked in the electricial contruction with schooling ,we were taught soldering connections was prohibited because high current can easily melt solder through overcurrent events or shorts.
    Pressure connections only.
    Soldering is for very low amperage devices only.

  • 2
    avatar F15Falcon says:

    I’ve been doing it the way described for years with no problems. I have used those connections on 18 and 24 volt systems with pretty high current draws. A pressure connection will work except that not very many people have the proper crimping tool to do a cable of that size. I have seen people try to crimp cable ends in a vise, only to have the connection fail at the worst possible moment.

  • 3
    avatar schon says:

    Good call, mel…high current creates heat…take and short a wire from positive to negitive and you get a booooooodacious spark (heat). It will melt the connection (solder)…crimp or drill and BOLT….

  • 4
    avatar Fredrik says:

    What about both crimping and soldering? then the solder will keep water out.

  • 5
    avatar n2omike says:

    I really like your articles, Tom. I really liked your write up on notching tubing with a chop saw. As a matter of fact, I believe it would be a great article to contribute to the front page, here. That was some great budget tech!

    As far as soldering this type of connection…. I did one this way around 15 years ago for the trunk mounted battery in the mustang. It’s still holding up just fine. The only time I ever got a battery cable hot enough to melt solder, is when I had a direct short. Now THAT melted all the insulation off the cable pretty much instantly!

    I -was- worried about a cold joint since the wire wasn’t heated up like the terminal end and solder, but it held just fine. However, I did get the end and solder VERY hot.

    Keep em’ coming!

  • 6
    avatar MikeG says:

    Couldn’t you just crimp the connection after soldering? Then, you get the best of both.

  • 7
    avatar blown68 says:

    If you guys are that worried, there is always silver solder. I know it’s expensive, but I luckily have a whole roll of the stuff. It does take quite a bit of heat to get it to flow, but it definitely will not melt if you have a high current draw. That is not to say solder won’t either because that is what I use and I have never had a problem doing it that way. I actually have a solder pot so i dip the whole connection in it and after it stops bubbling, I know the cable and terminal are completely bonded together. Plus, it’s fun to watch it go in coppery and come out all soldery!

  • 8
    avatar Ralph says:

    Wow. I solder all my connections. I guess you used fluxcore solder. I use flux used for copper tubing. most are water based now and are non corrosive. I think if I had a high current draw. I also would silver solder it, instead. don’t take much more heat and you do need to heat the wire for a good connection.

  • 9
    avatar RUSS THORNTON says:


  • 10
    avatar Aishah says:

    Hi, I really need to know few thing…
    For Dip Solder Process, what will be the temperature?
    and how to define the quality?
    Pls email me….

  • 11
    avatar Aishah says:


  • 12
    avatar george says:

    solder melt under hi current ? well ther wold be no heat if the conetion was good, low resistance lead is very low. and for the shorted cables i think i wold like my cable to un solder and fall apart befor the battery blows up

  • 13
    avatar jim says:

    when you are doing this sodering process shown are you tinning the cable first or no. i am replacing 2.0 cables on my golf cart witch is 48 volt and i am going to try the soder process.

  • 14
    avatar pat says:

    Just did a solder terminal on my battery electric truck. I’m running 144V and sometimes 500 amps. When my old crimped terminals go they take off the whole battery post! I think corrosion is getting under the heat shrink and the solder should fix that.

  • 15
    avatar On Site Battery Cable Repair says:

    We have a Hydro crimp we use for crimping our copper battery cable ends in the vehicle. Unit is shown in web site http://www.batterycablefix.com

  • 16
    avatar Russ Thornton says:

    We have a small hand held hydro Crimp for use with our copper battery cable ends. It is in our web site at http://www.batterycablefix.com

  • 17
    avatar Matt says:

    well it’s then it’s odd that new battery cables are sold with terminals soldered on. also, factory vehicle terminals are pretty much all soldered on. it’s a mere preference type thing.

  • 18
    avatar Matt says:

    don’t be a moron and ground your positive cable. using fuses or breakers is always an intelligent thing to do.

  • 19
    avatar ralphc says:

    I had Nelson Specialties, in Mooresville, NC make my race car battery cables. They have a crimping machine that makes the wire and terminal 1 piece. On anything 6 GA or smaller, they use high nickle crimp connectors which they crimp and solder. I started going to them after the cables on my hauler failed

  • 20
    avatar Nicholas says:

    I’m sure that’s true in electrical construction on the high end scale, but we’re talking about automobiles here, not production lines in a factory.

  • 21
    avatar Nicholas says:

    One more thing of which was already mentioned, If the solder gets hot enough to melt, you probably did not put an inline fuse in and what about the insulation melting? If the insulation melts than it does not matter what kind of connection you used in the first place.

  • 22
    avatar Steve says:

    Soldering is the best way to go. But, Mel is right about non automotive use. In non-low voltage use 48 volts on up never use solder on connections (or on neg 48 battery back ups). Automotive batteries are high amperage low voltage…Will start a fire but won’t hirt you. Building wiring is low amperage high voltage. Will also start a fire and will kill you! If you are worried about melting solder USE a fuse. Solder melts at about 365 F.

  • 23
    avatar jack says:

    I have been making this type of connection with no problems for about 15yrs now. I usually use 1 gauge fine strand wire, I have found this wire is very flexable and it can carry more current. The thicker the strands and thinner the wire, resistance will go up and so will the heat so I guess it could melt under those conitions. I have used old welding cable also with great results. I was using waterproof heat shrink on the ends which is a bit pricey, so I now wait for the joint to cool, coat the joint area and cable and lug with some glue from a hot glue gun, I then slide the correct size heat shrink into place and lightly heat it up with a butane torch. This melts the glue and activates the heat shrink as well. When done correctly the hot glue will ooze out both ends as the heat shrink, shrinks up. This pretty much makes it waterproof, these connections work out well on my CJ7 with no issues what so ever.

    just my 2 cents

  • 24
    avatar David says:

    Factory connections are NOT generally soldered, they are crimped. Wires can often go very hot during use (think of how many you have seen with melted insulation). Dielectric is an INSULATOR not a conductor. Use of a different gauge wire will override safety design. Buy a new cable pre-made or go to a shop that has cirmpers and the correct ends.

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