Lengthening battery cable length

[postmatic]

I've got a 72v lithium pack where one of the wires got a short and had to be shortened. Is it possible to lengthen the wires without having to cut into the pack? Got a couple differing opinions locally, one guy said I have to chop into the pack and put new wires the length I want. Someone else recommended butt connectors but I'm concerned about them melting as I am running a 70a controller. Does anyone know the ratings of butt connectors? Is it safer to just solder and heat shrink it?

Thanks in advance for any help. Cheers

 

[Diggs]

Sure. It's safe to solder and would be the preferred way I would do it. It would be good practice to use wire one gauge heavier than what is there already. Be sure you have good solder technique (clean, flux, tin, etc.) and full solder penetration.

 

[postmatic]

That was my initial thought but then got advice from others and started to question my own thinking

 

[pwd]

A good quality solder joint is fine if the connection isn't isn't under much physical stress (IE no movement required).

 

[Elmo]

soldering sounds like the way to go. just be careful and take your time with it.

 

[gromike]

I do solder splicing on battery wires fairly regularly. Solder spices can be difficult to do well on larger, finely stranded wires. You'll need a high wattage iron, and quality solder. I spread the wires apart and butt them together, compress the bundle, and then solder. It sure seems to eat a heck of a lot of solder!
But really, if you have the clearance, the way to do it is with a butt splice connector. In the trade the saying goes a listed connector crimped with a tool listed for that connector. Just saying, buy a quality butt splice connector and the tool that is made to crimp that style of connector.