Battery cable lugs: solder or crimp?

Bonnewagon

Lost in the Labyrinth
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Sep 18, 2009
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I need some new battery cables. Store cables are cheap and thin. I usually buy bulk lengths of marine grade tinned copper to make cables for outboard motors. I figured I would do the same for the Bonnewagon. The issue is that I read on electrical sites that crimping is the best way to attach the lugs. Normally I solder them. Every outboard cable I have seen was soldered. Some were even crimped AND soldered. I may do that. But why would crimping be better than soldering? That doesn't make sense. Solder would encapsulate every strand of wire. The soldered surface area of contact has to be better than crimping. I have a TEMco hammer crimper that I can use in a big vise or my 12 ton press so crimping is do-able. I am leaning to crimp-then solder.
 

awdblazer

Master Mechanic
Dec 12, 2013
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crimp is by far superior
i am an electrician by trade and we crimp everything unless its electronics and that is soldiered
 
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ELCAM

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Jun 19, 2021
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If things go wrong in the right way a battery cable can carry enough current and get hot enough to melt the solder. I have seen the cheap lead terminals melted from a stuck starter solenoid and a seized engine.

Soldering after crimping is a good idea.
 
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Built6spdMCSS

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Jun 15, 2012
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Crimp, then solder what you can see if you have any wire strands that are bare outside of the lug and the wire jacket. Then a little bit of heat shrink over it to cover it.
 
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Bonnewagon

Lost in the Labyrinth
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Sep 18, 2009
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crimp is by far superior

Soldering after crimping is a good idea.

Crimp, then solder
I am convinced. Crimp then solder seems like a belt-and-braces attitude but makes sense. I did read that the mechanical crimp connection was very important. But ELCAM nailed it. I did once have a starter lock up and melt the battery terminal. But there is a risk of high amperage getting the connector so hot as to melt the solder and set the hot cable loose. THAT can cause way more damage. So crimp, followed by solder, then my standard application of Liquid Lectric Tape, then shrink wrap, then more LLT. Works for boats, will work even better on the car. THANKS guys!!!
 
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86LK

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Jul 23, 2018
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don't know how good or expensive the marine cable is, or how much length you need, but there is an alternative. goto the junkyard, find a 90's BMW with trunk-mounted battery and pull the cable (thumb-thick) that runs up the engine. I think I paid about 50cents/ft for the cable I pulled, and it's nice and hefty

edit: forgot to mention that was about 20ft of cable too, as big around as my thumb. well worth the price
 
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Bonnewagon

Lost in the Labyrinth
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Marine cable is special in the way it is manufactured. The copper strands are coated with tin. That way if any moisture gets inside, the tin is sacrificial and protects the copper. That is important on a boat and I tend to use it on my cars just for the extra protection. When buying in bulk it is not much more expensive so to me it is worth it. Of course the shrink wrap and Liquid Lectric Tape all play a role too. I have wired many boats that way and I never have any electrical issues. By carrying that practice over to cars, I never have electrical issues on those either.
 
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Clone TIE Pilot

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Aug 14, 2011
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The main issue with solder is that it creates brittle points in wire. A good crimp should be airtight and so all the solder will due is coat the wire just outside the crimp, making that area stiff and brittle. However, good crimping tools and connectors are expensive besides knowing special techniques. I don't know about boatx but cars are subject to high vibrations that eventually cracks solder.
 
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Supercharged111

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Oct 25, 2019
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My vote is both. I once had a solder joint melt itself apart while driving and the whole car died. It was the alternator cable connection at the battery. This is back when I was in tech school, so I had a trunk full of tools and stuff. Luckily within that stuff was some 12ga wire and crimp terminals, so as a road side fix I wired up 3 12ga wires to charge the battery/run the car and we were off again.
 
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Bonnewagon

Lost in the Labyrinth
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Sep 18, 2009
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I don't know about boats but cars are subject to high vibrations
I don't think anything vibrates more than an outboard motor. Lokite is mandatory on everything. Outboards have been known to vibrate the mounting bolts/clamps loose and the motor ends up overboard. But I do think the soldering of lugs is more for corrosion protection on boats. Salt water gets into everything. Things that are standard on fresh water would not last a week on the salt.
 
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