[AT] Soldering battery cable

[Henry Miller]

On Saturday 21 October 2006 19:26, Dean Vinson wrote:
> I'm trying to make a new main battery cable for the M.  Got some 2/0 copper
> cable and some heavy-duty lugs, which are tinned with something so they
> look kind of silvery rather than copper.  Can I solder these together?
>
> I've got one end dry-fitted together, no flux, and tried to carefully heat
> it with a propane torch until it'd melt some standard rosin-core electrical
> solder.  Doesn't seem like the solder wants to flow, even into the copper
> strands, just beads up, so I'm afraid I'm making it too hot or I don't have
> the right materials or something.  Figured I'd better ask for advice before
> I screw this up.  Any help?  Should I use flux?  Take it to an electric
> shop?

First of all, make sure you really have copper, not aluminum.    You wouldn't 
be the first person to buy aluminum cable thinking it was tined copper.  
Though the problem isn't common, the price difference at that size of wire is 
significant enough that it can happen if you are not paying attention.

Second, assuming it is tinned, I suspect you are looking at silver solder 
which melts at much higher temperatures (nearly the temperature that aluminum 
melts at -  depending on the exact formula).   Lead solder is becoming very 
hard to find these days.   (Europe has outlawed lead solder for many uses 
such as consumer goods)   If this is the case, you could just add more heat.

In any case, you should never even THINK about soldering or brazing without 
flux.    

I personally HATE pre-tinned connectors.   They sound good on paper, but my 
experience is that there isn't enough solder to do the job.  (Mostly on 
pre-tinned pipes - I haven't worked with pre-tinned wire yet).   I personally 
would either get a good (rosin core) electric solder, and ignore whatever is 
on those cables.

Though before doing that I'd consider crimp connectors.   They don't take the 
abuse solder can, but when properly done they work great and are much easier 
to work with.   (Part of me is remembering that for house wiring you cannot 
solder connectors for reasons I can never remember, and this causes me to 
wonder if those reasons applie to 12 volt systems as well)

There are many options.   Pick one.   Though you would be well advised to 
check to see if anyone else knows something more about your specific 
situation.