Butt Splicing from Battery to Engine??

[Bycrick]

My math skills fail me, but conductivity (measured in MHOs) is the reciprocal of resistance (measured in OHMs). So solder is about 1/10 as conductive as copper.

[Bill Seal]

You're too old school, the POLITICALLY CORRECT term is Siemens. MHOs, like CYCLES per SECOND, made to much sense.

[Bycrick]

I learned about mhos when I was studying for my first commercial ticket in 1958. I don’t think I’ve used them since. They’ve changed everything else, why not that too.

[W2GL]

If you are adding a crimped connector to a stranded wire it isn't a good idea to add solder because the stranded wire becomes stiffer. This could lead to breakage as pointed out by another poster about a butt splice in a high vibration region near the engine. What ever you do, don't use solid wire for the same reason!

[bcboomer]

Can someone explain how a properly crimped butt connection is any more likely to fail than a properly crimped terminal lug.

[mitiempo]

Originally Posted by bcboomer

Can someone explain how a properly crimped butt connection is any more likely to fail than a properly crimped terminal lug.

It is not more likely to fail - with the emphasis on "properly crimped".

[john61ct]

Originally Posted by bcboomer

Can someone explain how a properly crimped butt connection is any more likely to fail than a properly crimped terminal lug.

The point is having any more joins than necessary is Bad.

But for the umpteenth time, if the join is done Right, and there's little weight/stress relief at the join, just check it periodically and you should be OK.

[Jim Cate]

Re the lower conductivity of solder vs copper: Yes, solder is less conductive, but we're talking about a layer a few thousandths of an inch thick. The added resistance, voltage drop and heating are infinitesimal in extent and not worth worrying about, even with high currents as in a starter supply.

And everyone is always wanting tinned wire... and tin isn't much better than lead for conductivity... and how about the tin or solder coating on the lugs themselves?

Try to keep these things in perspective!

Jim

[john61ct]

With DC electricity, the current runs through the whole cross section of the wire equally. Any resistance from tinning is only when that is perpendicular to, the flow goes "through" it, and in those cases negligible.

The "skin effect" is AC only, flowing more at the surface especially at higher frequencies.

With a proper crimp - gas tight cold welded, there is no place for solder to get in the join anyway, adding solder **does nothing helpful**, only potentially harmful.

[Q Xopa]

Originally Posted by john61ct

With DC electricity, the current runs through the whole cross section of the wire equally. Any resistance from tinning is only when that is perpendicular to, the flow goes "through" it, and in those cases negligible.

The "skin effect" is AC only, flowing more at the surface especially at higher frequencies.

With a proper crimp - gas tight cold welded, there is no place for solder to get in the join anyway, adding solder **does nothing helpful**, only potentially harmful.

All the techno babble aside your last paragraph is something we can agree on. Proper crimps are considered the best by people much smarter than me.

Although I have recently been accused of this being advocating perfection and not practical in the real world.

I do agree with that, although we should try for perfection in the real world we might not make it. Sometimes we gotta do what we can to get the job done.

[john61ct]

Absolutely, plenty of real-life owners just want what they consider good enough.

Or even just the bare minimum required to keep going, and if problems arise deal with it then.

That approach may be all that's possible sometimes, and temporary MacGyver fixes can have their own beauty, even elegance