Making up your own cables

[mj52]

Hi,

Should battery cables be the same length when wiring between batteries?

What about between batteries and other pieces of equipment?

Once the conector is mechanically attached should you solder as well?

What about heat shrink?

Thanks mj52

[CA_Tom]

Hi,

Should battery cables be the same length when wiring between batteries?

What about between batteries and other pieces of equipment?

No reason to - it's not like different channels on a video output or something where there's a high frequency signal.
Cables should be as short as reasonably possible. Shorter == less resistance and less cost in materials. But balance that against getting it in place (and moving the cable to access things if needed)

[mj52]

I agree, never cut anything at Banjo String tension. A relaxed fit is always better.

But what about when 2 properly fitted cables have an 18" difference in length? Are you saying there is negligible difference between a 15 and 33" length of properly sized wire? This makes sense to me. If you had a 50" coil laying on the floor I could see that being an issue. Sometimes 1 lead must be longer than another.

But now what about soldering a good mechanical splice? Wouldn't that just fill in the nooks and crannies which would help to keep corrosive problems at bay?

Thanks, mj52

[FunGas]

Why wouldn't you solder and insulate the ends, I have a fairly small-scale 12V 40A battery pack and re-discovered Elmo's fire even though the connectors have heatshrink on them.

Soldering reinforces the joint and the extra insulation provides strain-relief and reduces the possibility of fraying.

Yes, make a proper job of it and don't underestimate the importance of same-length wiring...

[Mike90250]

Soldering a well crimped joint is somewhat OK, but the problem is that the solder wicks up the wire and makes a stiff spot. This causes increased cable flex at the edge of the the stiff spot, and the cable can fail from that.

A properly crimped lug also has a sealed end, so there is no way to reliably get solder into it anyway.

And the problem with soldered lugs, is that if there is a high current fault, the solder melts before the wire does, and sometimes explodes with molten solder spray all over.

So, if you have good circuit protection, and the cables are not subject to any movement, it may be possible to solder. But a hydraulic 6 ton crimp, if going to be fine if properly done, the pressure cold welds the cable to the lug.