Dual battery cable

Hey guys. First thread and very new to the 4wd scene! Been watching n checking out everyone's rides. Inspirational, hopefully I get my Stx to the level that some people have. Enough of that, my first real DIY mod is my dual battery system. I've made a box to house the battery with a lil extra storage space (will post some photos when I get a chance). Now I have got some 16mm copper cable which is used for a 240v application normally. Will this be alright to use for my link between the aux battery and the redarc isolator??

As far as Im aware using 240v house cable is a absolute no no. Im sure others will explain why.

Effectively the right "overall" size but 16mm sdi is a solid multicore cable and the stuff you need is a stranded cable. The stranded stuff can carry more current the solid and due to it being stranded can indure more flex and movement. More strands, thinner wire = more give or flex.
Not the most technically correct way of putting it, but prolly the easiest.
That's coming from a sparky anyway.... :s

Yep, flex is used on vehicles because of vibration etc it is less likely to fatigue and break de to less rigidity, easier to bend around corners etc.

Don't use 240V cable. The solid stuff (single core, not multistrand) won't like being jostled on the road - your house sits rather still (except when the V8 supercars are on). Eventually the cable will snap. Saw this on a cable in a D21 engine bay - Someone (maybe Nissan) used a single-core wire from the battery to the connectors heading to the vehicle's circuitry. It started to flex and weaken at one point then with the high DC current it went off like a fuse.

For the long cable run, try something higher than 6 sq mm cable. Supercheap Auto have 100A jumper leads (4GA) for sale - join some of that together!

Yeah as everyone is saying don't use the standard house wiring cable, its not designed to be moved once installed, the strands will crack.

Go to an electrical wholesaler and get double insulated weld flex, i'd use a 35mm, should cost about $6-$7 a meter, they will try to charge you a cutting charge of $80 but they don't get charged it for welding flex so tell them to bugger off.

Also at the wholesalers get the correct lugs for the ends, get them to order flared lugs for you, the normal lugs they will have in stock are the same size but you can't ever get all the strands in them. Chuck a sparky a 6 pack and get them to crimp the lugs on for you, you need the proper crimping tool, they are about $270.00 if you want to buy one.
I always put a bit of sikaflex (tiny bit) on the back of the crimped lug where the insulation butts up against it and heat shrink over the lot, stops the cable corroding (more prevalent in boats).
And finally, the front of the lug will have a little hole in it where you can see the strands of the cable, the strands should be pushed hard up to that hole, fill the end of the lug with solder, it makes an awesome connection and seals the end against corrosion.

Thanks for the input guys. Ive heard a lot of different opinions about if i can use it or not. heres a couple of pictures of the box i made and the cable i was planning on using.

The cable isnt standard household cabe, its what we use to run from the powerlines to the service box on the poles. heavy duty stuff. I have access to all the lugs, heatshirnks and crimpers so no problems there. I also have access to some other types of cable which is multstranded alum. So i dont know if that is better or not?

Thanks again for all the help with this

Yeah that's the one I'm referring to mate, 7 strand no, no good. You'll need a flexible cable

I wouldn't use that cable and wouldn't use the aluminium cable either. Problem with Al cable is that while it's a better conductor than copper, it's far more brittle than copper and even a multistrand Al cable will suffer from vibration and movement over time.

Aluminium is a worse conductor than copper actually Tony, hence Al cables have to be a fair bit bigger to achieve the same current rating. Also, aluminium suffers from metal fatigue more than copper so is a definite no no in a car

I was reading from my old SI materials handbook - the relative electron propagation from an Al atom is higher than for that of Cu, but in a wire it's obviously different. That'd be the larger crystalline structures that Al forms versus Cu.

Jesus! I'll take your word for that.

I'd like to know what the principles are for silver and gold, as these are better conductors again.

@Trav, just wicki 'material electrical conductivity'

Hey guys me again I've finally fired up and want to get this dual battery happenig again. I've bought my battery and I went an got some 6b&s heavily insulated cable. Now I have got a redarc isolator with override function and Am worried that the cable is going to be too small to start with the aux battery. What u guys think, get away with it?

Djsimo23 said:

Hey guys me again I've finally fired up and want to get this dual battery happenig again. I've bought my battery and I went an got some 6b&s heavily insulated cable. Now I have got a redarc isolator with override function and Am worried that the cable is going to be too small to start with the aux battery. What u guys think, get away with it?

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That size cable is plenty big enough, I am using the 6b&s in mine. I have had to start the car up from the second battery twice as my main battery died, did it with no problems.